Zoltán Weltsch

36667788100

Publications - 25

Improving battery safety and sustainability through testing material advances and industry developments

Zoltán Weltsch Tibor Cseke Robert Kun

Publication Name: Discover Sustainability

Publication Date: 2025-12-01

Volume: 6

Issue: 1

Page Range: Unknown

Description:

The transition to renewable energy is essential for sustainable development, in which advanced energy-efficient storage solutions, in particular rechargeable batteries, play a key role. Batteries are becoming increasingly important not only for electric mobility and grid balancing, but also for industrial and residential applications. However, as energy density increases, so do safety risks such as thermal runaway, which can jeopardise user confidence. The aim of this study is to examine the battery technology value chain at a systemic level, with a particular focus on the role of safety testing and technological innovation. The research identifies three main gaps in literature: the lack of value chain level integration, the under-representation of AI-based safety technologies, and the limited comparison of regional (EU, US, Asia) regulatory regimes. By examining the interrelationships between material selection (cathode, anode), cell design, testing protocols and regulatory environment, the study highlights the complex challenges and development directions for battery energy storage. The study reviewed global industry trends and critically assessed forecasts and analyses from international consultancies such as Ernst & Young (EY). These concluded that thorough testing of lithium-ion batteries is key to ensuring long-term reliability, safety and performance by reducing operational risks and increasing product efficiency. Advanced testing infrastructure not only serves quality control and regulatory compliance, but also makes a fundamental contribution to increasing energy efficiency and supporting the green transition. For Europe in particular, it is of paramount importance to expand testing capacities to enable the continent to take a leading role in the safe and sustainable development of batteries.

Open Access: Yes

DOI: 10.1007/s43621-025-01717-5

Impact of recycling on polymer binder integrity in metal injection molding

F. Ronkay Zoltán Weltsch György Ledniczky Pál Hansághy

Publication Name: Scientific Reports

Publication Date: 2025-12-01

Volume: 15

Issue: 1

Page Range: Unknown

Description:

Metal Injection Molding (MIM) is a manufacturing process that integrates polymer binders with metal powders to produce high-precision components, offering both material efficiency and design flexibility. This study explores the recyclability of polymer-based feedstocks used in Metal Injection Molding, specifically evaluating how repeated recycling affects the structural integrity and thermal stability of polymer binders. Given the high cost of raw materials in MIM, optimizing recyclability is essential for reducing production costs and minimizing material waste, contributing to more sustainable manufacturing practices. To assess the feasibility of repeated material reuse, the study systematically subjected molded specimens to grinding and reinjection molding over eight consecutive cycles. The effects of reprocessing were analyzed using melt flow index (MFI) measurements, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) to track changes in polymer viscosity, thermal behavior, and degradation. The results indicate that wax precipitation during processing alters polymer viscosity and thermal stability, leading to gradual material property changes over successive recycling cycles. However, polymer degradation-induced viscosity reduction counterbalances these effects up to the fourth cycle, ensuring processability within standard injection molding conditions. The findings underscore the significance of analytical techniques in evaluating polymer binder integrity during multi-cycle reuse. Melt flow index (MFI) initially increased, peaking at the fourth recycling cycle, and then declined, while linear shrinkage rose by approximately 3% within the first three cycles before stabilizing. SEM–EDS analyses indicated around a 20% wax loss after multiple recycling cycles, significantly influencing binder rheology. Polymer binders can thus be successfully recycled up to four times while maintaining acceptable thermal and rheological properties, supporting resource-efficient and sustainable manufacturing strategies in MIM production.

Open Access: Yes

DOI: 10.1038/s41598-025-05577-x

Optimizing adhesion in aluminum alloys: A cross-disciplinary approach to surface treatment and bond strength

Zoltán Weltsch Miklós Berczeli Ferenc Tajti

Publication Name: International Journal of Adhesion and Adhesives

Publication Date: 2025-09-01

Volume: 142

Issue: Unknown

Page Range: Unknown

Description:

As the use of aluminum structures grows due to their lightweight properties and sustainability advantages, optimizing bonding technologies is essential for ensuring strong and durable joints. This study systematically evaluates fourteen surface treatment methods applied to aluminum sheets and L-section joints, assessing their influence on adhesion performance. Surface preparation significantly impacted bond strength. Veil sanding combined with Sika® Primer-207 led to an 82 % increase in tensile strength and a 258 % increase in shear strength compared to untreated surfaces. Laser and hot deionized water treatments resulted in the highest measured surface energy (88 mN/m), improving wettability and adhesive-substrate interaction. To analyze bonding performance, a flexible polyurethane adhesive was applied to structural joints, which were tested under tensile and shear stress conditions. The results demonstrated that surface roughness, free energy, and chemical modification strongly influence failure modes. While untreated surfaces predominantly exhibited adhesive failure, optimized treatments shifted failure toward cohesive failure, indicating a stronger interfacial bond. Additionally, the correlation between surface free energy, surface roughness, and adhesive strength was examined to understand their combined effects on joint performance. The findings highlight the importance of selecting appropriate surface modification techniques to maximize adhesion and joint durability. This research provides practical insights for industries relying on aluminum bonding, offering guidance on optimizing surface treatment protocols to enhance structural integrity and long-term reliability in demanding applications.

Open Access: Yes

DOI: 10.1016/j.ijadhadh.2025.104068

Full-surface geometric analysis of DMLS-manufactured stainless steel parts after post-processing treatments

Zoltán Weltsch Valentin Szabó

Publication Name: Results in Engineering

Publication Date: 2025-09-01

Volume: 27

Issue: Unknown

Page Range: Unknown

Description:

The study examines the geometric behavior of corrosion-resistant steel components manufactured using the DMLS (Direct Metal Laser Sintering) process after various post-treatment methods. Full-surface 3D optical scanning was used to evaluate geometric deviations before and after three different treatments: stress relief heat treatment, immediate base plate removal, and natural aging. The results showed that heat treatment amplified the distortions caused by existing residual stresses, with elliptical deformation nearly doubling (i.e., deteriorating by approximately 200 %). Immediate removal resulted in asymmetrical, teardrop-shaped distortion that exceeded the ±0.1 mm tolerance limit. Natural aging effectively stabilized the geometry, with circularity deviation remaining within the ±0.1 mm limit. The results highlight the critical role of thermal management and post-processing in ensuring the dimensional accuracy of DMLS parts. The research demonstrates the advantages of full-surface, high-precision optical metrology in the detailed analysis of shape changes occurring during additive manufacturing, with the maximum permissible error of the measuring system limited to 0.01 mm in our measurements.

Open Access: Yes

DOI: 10.1016/j.rineng.2025.106084

Future of Agrivoltaic projects: A review from the technological forecasting perspective

Zoltán Weltsch András Háry Xue Chao Wang Ting Pan Leticia Pekk Bernadett Rádli-Burján Petar Sabev Varbanov

Publication Name: Cleaner Engineering and Technology

Publication Date: 2025-09-01

Volume: 28

Issue: Unknown

Page Range: Unknown

Description:

Agrivoltaic systems integrate photovoltaic (PV) energy generation with agricultural production, creating synergies that enhance land-use efficiency and environmental sustainability. This article reviews agrivoltaic technologies to identify key trends and the most promising future research and development directions. The method applied involves selecting and analysing relevant literature sources and filtering them with regard to the essential questions that need to be answered for the climates of Central Europe and China. These include global development, current applications, and technological progress. The analysis reveals growing attention to system design, performance optimisation, and crop compatibility. Innovations such as bifacial and spectrally selective PV modules boost energy yields while maintaining suitable conditions for shade-tolerant crops like leafy greens and berries. The analysis confirmed the high potential of sustainability benefits (societal, economic, and environmental) and revealed the need for systematic investigations of significant performance factors, including location and system design. A relatively underinvestigated factor is the protection of crops from excessive sunlight, which has become increasingly important. The modelling and optimisation of system operation is also necessary to provide decision-makers with robust tools for project assessment. A roadmap is proposed to guide future research and development.

Open Access: Yes

DOI: 10.1016/j.clet.2025.101057

Experimental Validation and Optimization of a Hydrogen–Gasoline Dual-Fuel Combustion Model in a Spark Ignition Engine with a Moderate Hydrogen Ratio

Zoltán Weltsch Krisztián Kun Bálint Szabó Attila Kiss Barna Hanula

Publication Name: Energies

Publication Date: 2025-07-01

Volume: 18

Issue: 13

Page Range: Unknown

Description:

Hydrogen–gasoline dual-fuel spark ignition (SI) engines represent a promising transitional solution toward cleaner combustion and reduced carbon emissions. In a previous study, a predictive engine model was developed to simulate the performance and combustion characteristics of such systems; however, its accuracy was constrained by the use of estimated combustion parameters. This study presents an experimental validation based on high-resolution in-cylinder pressure measurements performed on a naturally aspirated SI engine operating with a 20% hydrogen energy share. The objectives are twofold: (1) to refine the combustion model using empirically derived combustion metrics, and (2) to evaluate the feasibility of moderate hydrogen enrichment in a stock engine configuration. To facilitate a more accurate understanding of how key combustion parameters evolve under different operating conditions, Vibe function was fitted to the ensemble-averaged heat release rate curves computed from 100 consecutive engine cycles at each static full-load operating point. This approach enabled the extraction of stable and representative metrics, including the mass fraction burned at 50% (MFB50) and combustion duration, which were then used to recalibrate the predictive combustion model. In addition, cycle-to-cycle variation and combustion duration were also investigated in the dual-fuel mode. The combustion duration exhibited a consistent and substantial reduction across all of the examined operating points when compared to pure gasoline operation. Furthermore, the cycle-to-cycle variation difference remained statistically insignificant, indicating that the introduction of 20% hydrogen did not adversely affect combustion stability. In addition to improving model accuracy, this work investigates the occurrence of abnormal combustion phenomena—including backfiring, auto-ignition, and knock—under enriched conditions. The results confirm that 20% hydrogen blends can be safely utilized in standard engine architectures, yielding faster combustion and reduced burn durations. The validated model offers a reliable foundation for further dual-fuel optimization and supports the broader integration of hydrogen into conventional internal combustion platforms.

Open Access: Yes

DOI: 10.3390/en18133501

Relationship between the developed interfacial area ratio and the adhesion of the bonded joint

Zoltán Weltsch Miklós Berczeli Benjámin Körömi

Publication Name: Journal of Advanced Joining Processes

Publication Date: 2025-06-01

Volume: 11

Issue: Unknown

Page Range: Unknown

Description:

Bonding technologies have evolved significantly over the past decades, playing a crucial role in the field of joining technologies. To date, however, there is no consensus among research groups as to whether surface texture or surface wettability, or both, affect the strength of bonded joints. Bonded joints, as a bonding technique, are highly dependent on the chemical composition of the adhesive or binder. It is also important to note that the strength and the quality of a bonded joint is greatly influenced by surface adhesion and its related phenomena. From a materials science perspective, surface adhesion is characterised by the level of surface wetting and the total surface energy. In addition, microtopographies and other geometrical features play a key role in bond formation. In this research, the goal is to create controlled microtopographies on DP600 steel surfaces, mainly using femtosecond pulsed laser surface treatment techniques. The ability of adhesives to fill microtopographies specifically, the extent and manner in which micro-scale geometries and structures are filled is also investigated. This allows for the establishment of correlations between the strength of adhesive bonds and the shape characteristics of the microtopography, both in the surface-activated and non-surface-activated states.

Open Access: Yes

DOI: 10.1016/j.jajp.2025.100310

Advances in Standardised Battery Testing for Enhanced Safety and Innovation in Electric Vehicles: A Comprehensive Review

Zoltán Weltsch Tibor Cseke Soma Fullér Márton Pepó

Publication Name: Batteries

Publication Date: 2025-04-01

Volume: 11

Issue: 4

Page Range: Unknown

Description:

Standardised battery tests are essential for evaluating the safety, reliability, and performance of modern battery technologies, especially with the rapid emergence of innovations such as solid-state and lithium–sulphur batteries. This review reveals critical shortcomings in current international standards (e.g., IEC, IEEE, SAE), which often do not keep pace with technological developments and are not harmonised across regions, limiting their effectiveness in real-world applications. The paper stresses the need for the continuous review of test protocols through collaboration between researchers, manufacturers, and regulators. A detailed case study of the BYD Dolphin battery demonstrates the practical importance of comprehensive testing in real-world conditions, spanning electrical, thermal, and mechanical ranges. The review concludes that up-to-date, harmonised, and scenario-specific test methods are needed to ensure accurate battery assessment, support global comparability, and enable the safe introduction of next-generation batteries for electric mobility and energy storage. Future work should prioritise operational monitoring, open access data sharing, and the development of sustainability-focused practices such as recycling and reclamation.

Open Access: Yes

DOI: 10.3390/batteries11040157

Determination of Natural Frequencies with Acoustic Methods and their Relation to Residual Stress

Zoltán Weltsch Alexandra Kiri

Publication Name: Advances in Science and Technology

Publication Date: 2025-01-01

Volume: 165 AST

Issue: Unknown

Page Range: 199-204

Description:

There are number of different methods and procedures in vibration analysis, where the natural frequencies of the specimen or the system are one of the key parameters. It is known that these frequencies can change under load, for example in response to pre-stressing, but the effect of residual stresses is less known. By developing a suitable method, natural frequencies can be used to predetermine residual stress, therefore this method can be used for example predicting whether it will cause deformation during machining of a part, whether it requires increased attention or how to set the parameters well for vibratory stress relief. The results can be significant cost and time savings, as well as the improvements of the quality. Natural frequency is the frequency of free vibration of an undamped linear vibration system, or in other words at which a system left alone will vibrate after excited by an external force [1]. Metal castings or welded structures may have several natural frequencies which appear as frequency bands or ranges on the measurement images. Based on these, to determine the natural frequency of a component or system, we need to excite a frequency as close as possible to the natural frequency for the resonance to occur. When the resonance is reached, the amplitude of the system is at its maximum, and the natural frequencies of the workpiece can be measured. Traditionally, sensors, usually accelerometers are used to measure the natural frequency. The continuous development of information technology has made it possible to replace these sensors with an acoustic diagnostic system. During this research, we have developed an acoustic diagnostic system and procedure, which can generate the acoustic measurement images. We have evaluated the measurement images in many ways, and many different types of components and materials (mostly iron alloys) were analyzed. In addition, the changes of natural frequencies show a similar pattern in the case of parts before treating with vibratory stress relief as for load tests.

Open Access: Yes

DOI: 10.4028/p-e4cRIL

Literature Review of the Behaviour of Adhesive Joint Fatigue Performance

Zoltán Weltsch Miklós Berczeli Péter Péczi-Kovács

Publication Name: Materials Science Forum

Publication Date: 2025-01-01

Volume: 1153

Issue: Unknown

Page Range: 23-32

Description:

Adhesive joints are essential in modern engineering, offering lightweight, durable and efficient solutions for bonding in industries such as aerospace, automotive, and renewable energy. However, their fatigue performance under cyclic loading remains a critical challenge, shaped by a complex interplay of geometrical, material, environmental, and loading factors. This review explores the mechanisms of fatigue failure, highlighting the importance of joint design, material optimization, and surface preparation in mitigating stress concentrations and enhancing durability. Advances in toughened adhesives, surface treatments, and environmental protection methods are highlighted, along with predictive models ranging from empirical S-N curves to advanced finite element simulations and probabilistic approaches. Despite significant progress, challenges remain in integrating these techniques for real-world applications, particularly under variable loading and harsh environmental conditions. Future research must focus on hybrid methodologies, adaptive materials, and standardized protocols to bridge the gap between laboratory insights and practical implementations. This comprehensive review provides a foundation for improving the fatigue performance of adhesive joints, ensuring their reliability and effectiveness in critical engineering systems.

Open Access: Yes

DOI: 10.4028/p-F2MUdc

Prediction of Efficiency, Performance, and Emissions Based on a Validated Simulation Model in Hydrogen–Gasoline Dual-Fuel Internal Combustion Engines

Zoltán Weltsch Krisztián Kun Bálint Szabó Attila Kiss

Publication Name: Energies

Publication Date: 2024-11-01

Volume: 17

Issue: 22

Page Range: Unknown

Description:

This study explores the performance and emissions characteristics of a dual-fuel internal combustion engine operating on a blend of hydrogen and gasoline. This research began with a baseline simulation of a conventional gasoline engine, which was subsequently validated through experimental testing on an AVL testbed. The simulation results closely matched the testbed data, confirming the accuracy of the model, with deviations within 5%. Building on this validated model, a hydrogen–gasoline dual-fuel engine simulation was developed. The predictive simulation revealed an approximately 5% increase in overall engine efficiency at the optimal operating point, primarily due to hydrogen’s combustion properties. Additionally, the injected gasoline mass and CO2 emissions were reduced by around 30% across the RPM range. However, the introduction of hydrogen also resulted in a slight reduction (~10%) in torque, attributed to the lower volumetric efficiency caused by hydrogen displacing intake air. While CO emissions were significantly reduced, NOx emissions nearly doubled due to the higher combustion temperatures associated with hydrogen. This research demonstrates the potential of hydrogen–gasoline dual-fuel systems in reducing carbon emissions, while highlighting the need for further optimization to balance performance with environmental impact.

Open Access: Yes

DOI: 10.3390/en17225680

Changing the High Strength Steel Surface Properties with Femtosecond Laser Beam

Zoltán Weltsch G. Juhász Miklós Berczeli Ferenc Tajti

Publication Name: Optics and Laser Technology

Publication Date: 2024-07-01

Volume: 174

Issue: Unknown

Page Range: Unknown

Description:

Today, the automotive industry is undergoing rapid change. While manufacturers are constantly switching to fully or semi-electric hybrid models, the weight of the vehicles also increases significantly due to the extra weight of the batteries. Since the weight of vehicles has the most significant influence on their consumption and, with it, harmful emissions (even indirectly far from the place of use), manufacturers strive to keep weight under control with continuous improvements. One of the main directions of the developments is the use of new light but at the same time heavy-duty materials with a wide variety of material combinations. These new material pairings pose challenges to knitting technology solutions, which need to be developed similarly. In the course of our research, we are investigating how the surface properties can be optimized in the case of steel with increased strength for the automotive industry, without additional added material and changes visible to the naked eye. We subject the examined DP600 material to a short-pulse laser beam treatment, and we manage to change the surface structure so that the interface properties measured by wetting are significantly improved. The results are confirmed by electron microscopic examinations.

Open Access: Yes

DOI: 10.1016/j.optlastec.2024.110556

Concept of a Novel Energy Management System for Microgrids and Energy Communities

Balázs Vehovszky Zoltán Weltsch Bernadett Rádli-Burján Ferenc Magyar Lóránt Kovács

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 919-924

Description:

The green transition of the global energy system presents considerable economic and technological challenges. One of them is the local and temporal difference between available energy sources and energy demand. To overcome this problem, two conceptual solutions can be considered: one is the use of an energy carrier that is suitable for medium- and long-term storage and safe transportation of energy. Carbon-based fuels (or novel alternatives, like hydrogen) or electric energy are the solutions currently used; however, we are facing their environmental or technical limitations. The other one is the synchronisation and intelligent control of sources and consumers, which could significantly decrease the storage and transportation needs. The current article discusses such a solution through a conceptual example. For the conceptual design of an advanced energy management system, the main related system elements shall be defined, and characteristic properties must be assigned to them. Input parameters for the energy management strategy must be given and prioritised. All this information enables the system to calculate and define instantaneous operational optimum. Also, an intelligent control system should take time-dependent processes and parameters into account, which can be deterministic or stochastic. As a result of this study, an energy management system concept that is based on realistic components and use cases is proposed, and its applicability to a local energy community is evaluated.

Open Access: Yes

DOI: 10.3303/CET24114154

Concepts and Examples of Carbon-Free, Self-Sufficient Local Energy Systems

Balázs Vehovszky Zoltán Weltsch Ferenc Magyar Lóránt Kovács

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 931-936

Description:

The necessity of the “green revolution” in the field of energetics is not a question anymore; however, switching the current fossil fuel-based energy ecosystem to a fully renewable-based one poses enormous challenges. The historical structure of the present, centralised energy production infrastructure, as well as the fundamentally different characteristics of the three main fields of usage (electricity generation, heating and transportation), are among the most substantial hindering factors. The future energy system has to be much more flexible in several respects, with a fundamental contribution of smaller, independent energy communities. The current study focuses on the realisation aspects of such a small-scale energy community (or micro/nano-grid), considering the suitable technological solutions as well as the cost concerns. A high number of pilot projects and case studies around the world prove that the technical feasibility of a local grid/energy community is no longer a question. The real challenge is to find the appropriate incentives and strategy to catalyse the required transition at the legislation, system operator and end-user level as well. The outcomes of the present work contribute to this goal by pointing out the application potentials of a modular, scalable microgrid system based on a currently running microgrid-realization project at the ZalaZONE proving ground.

Open Access: Yes

DOI: 10.3303/CET24114156

Combination of Sustainable Agriculture and Renewable Energy Systems

Balázs Vehovszky Zoltán Weltsch Bernadett Rádli-Burján Ferenc Magyar Lóránt Kovács

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 913-918

Description:

It is now not a question anymore that the fossil fuel-based energy system of human civilization has to be converted into a sustainable energy cycle during the 21st century. In most cases, the introduction of related, novel energetical technologies and solutions leads to disadvantageous interferences with other fields of life. Perhaps the most critical example is the competition between the energy sector and the food industry for valuable agricultural land. Although the two utilization purposes are generally considered mutually exclusive, there are agro-energetical solutions where the two goals are not just indifferent, but they expressly increase each other's efficiency. Such solutions are the agro-photovoltaic systems, where photovoltaic panels are installed in a way that is advantageous for the crops below them. Some plants, such as berries, prefer shady to semi-shady environments, which can be optimally provided under partially covered PV fields. With the active control of the PV panels, ideal shading conditions and even mechanical protection can be ensured in case of extreme weather events. With the appropriate selection of the crop plants and the PV installation, cultivation processes are not hindered, can be highly automated, and the energy needs can be fully covered by the local PV system. From the above description, it is clear that the realization of efficient agro-photovoltaic systems is not just possible but really prosperous. This study offers a more detailed overview of currently realized solutions around the world, as well as a thorough planning process of an agro-photovoltaic project at the ZalaZONE test center, optimized for the Hungarian climatic and agricultural conditions and possibilities.

Open Access: Yes

DOI: 10.3303/CET24114153

COMPARISON OF THE MOLDING PARAMETERS EFFECTS ON METAL INJECTION MOLDED SPECIMENS IN THE REAL EXPERIMENTAL AND SIMULATION ENVIRONMENTS

Zoltán Weltsch György Ledniczky

Publication Name: Communications Scientific Letters of the University of Zilina

Publication Date: 2024-01-01

Volume: 26

Issue: 2

Page Range: B90-B98

Description:

This article presents a technology that is not widely known. Previous research has investigated the effect of metal injection molding parameters on product shrinkage. The technology is mostly limited by the variations caused by deformation, so it is of paramount importance to focus on shrinkage. Consequently, within this study the injection molding simulations with 17-4PH type material was performed and its results were compared to the previously determined curve characters. The results obtained allow conclusions to be drawn regarding the accuracy of the simulation. Changing the parameters of the injection molding process can significantly affect the shrinkage factor. Changes in mold temperature, melt temperature and holding pressure affect the product dimensions. These parameters are also modified in the simulation setup and compared to the previous real measurements.

Open Access: Yes

DOI: 10.26552/com.C.2024.018

Sustainable Economic Growth through Battery Innovation: The Impact of Industry Expansion and Testing Capacities in Hungary

Zoltán Weltsch Peter Simon Tibor Cseke

Publication Name: Chemical Engineering Transactions

Publication Date: 2024-01-01

Volume: 114

Issue: Unknown

Page Range: 889-894

Description:

In an era where sustainability has become a pivotal concern, the battery industry emerges as a beacon of hope for innovation and economic transformation. Batteries are a cornerstone of sustainable development. They provide an essential energy storage function, facilitating the transition to renewable energy sources and decarbonization. Batteries enable efficient storage and distribution of renewable energy and reduce dependence on fossil fuels. This results in mitigating environmental pollution and contributing to a more sustainable energy landscape. Batteries are, therefore, a fundamental driver of both energy and environmental sustainability. The integration of testing capacities in battery factories and third-party locations is crucial for ensuring product reliability, safety, and performance. In turn, this reinforces market confidence and consumer adoption of the new sustainable applications batteries support. By investing in advanced testing facilities, the industry adheres to stringent quality standards and promotes technological advancements and R&D. This contributes to the economic and sustainable growth of the sector. This approach demonstrates a commitment to continuous innovation, product excellence, and a multitude of sustainability factors, highlighting the essential role of testing in the burgeoning battery industry. In summary, the battery industry is at the intersection of sustainability and economic growth. Our publication shows how the strategic infrastructure development of the innovation-focused battery sector can offer a new perspective on achieving sustainable and economic growth and how it can play a key role in this global transformation.

Open Access: Yes

DOI: 10.3303/CET24114149

DEVELOPMENT OF THE BONDING TECHNOLOGY OF MODERN AUTOMOTIVE MATERIALS WITH ENVIRONMENTALLY FRIENDLY SOLUTIONS

Zoltán Weltsch Miklós Berczeli Ferenc Tajti

Publication Name: Communications Scientific Letters of the University of Zilina

Publication Date: 2024-01-01

Volume: 26

Issue: 2

Page Range: B135-B141

Description:

The significance of bonding technology for modern vehicle structural materials is increasingly acknowledged, driven by the adoption of new materials to reduce weight. This is important not only for quality and economic reasons but to address environmental pollution, as well. Traditional joining methods like riveting, screwing, welding, and brazing, are often unsuitable or limited for modern materials. Soldering, an economical and almost waste-free technology, is becoming more widespread. Through optimization, it achieves a strong, durable bond. There is a potential to favourably alter interface properties, including using high energy density surface treatments. Research showed that the laser surface treatment of high-strength steel sheets could improve the mechanical properties of soldered joints.

Open Access: Yes

DOI: 10.26552/com.C.2024.026

EFFECT OF ENVIRONMENTAL CONDITIONS ON CURING OF POLYURETHANE ADHESIVE INVESTIGATED WITH FTIR ANALYSIS

Zoltán Weltsch Miklós Berczeli Péter Kovács

Publication Name: Communications Scientific Letters of the University of Zilina

Publication Date: 2024-01-01

Volume: 26

Issue: 2

Page Range: B118-B127

Description:

The use and significance of adhesives in various industries are explored, highlighting the growth of the adhesive market and the crucial role of time in adhesive bonding. The composition of adhesives, particularly polyurethane adhesives (PUR), is detailed, emphasizing their sensitivity to environmental factors, like moisture and UV radiation. Various factors influencing adhesive properties, such as reactivity and curing-induced shrinkage, are discussed, along with the importance of catalysts in adjusting reaction rates. One-component moisture-curable PUR adhesives are presented as versatile and continually improving alternatives in structural adhesive applications. The research's focus was to investigate the curing speed of Sikaflex-252 1-component PUR structural adhesive under different conditions, including room temperature, room temperature with ~30% humidity, and room temperature with ~100% humidity.

Open Access: Yes

DOI: 10.26552/com.C.2024.024

Effects of Reprocessing on Surface Oxidation and Microstructural Composition in Metal Injection-Molded Materials: Insights from SEM, EDX, and Metallographic Analysis †

Zoltán Weltsch Ferenc Tajti György Ledniczky Sándor Marokházi

Publication Name: Engineering Proceedings

Publication Date: 2024-01-01

Volume: 79

Issue: 1

Page Range: Unknown

Description:

This paper explores the evolving significance of metal injection molding (MIM) technology, particularly as a promising alternative for the precise and cost-effective manufacturing of small-scale, high-volume products in the automotive industry. Despite its growing adoption, the quality control processes for intermediate “green” parts and the final metal products are not yet well established, posing significant challenges in ensuring product reliability and consistency. Furthermore, the research thoroughly examines the recycling of MIM feedstock and its impact, especially on the change in carbon content. Scanning Electron Microscopy (SEM) images were taken of the samples, the chemical composition was analyzed using Energy-Dispersive X-ray Spectroscopy (EDX), and the pearlitic regions of samples from different generations were compared using image analysis software on microscopic cross-sections.

Open Access: Yes

DOI: 10.3390/engproc2024079009

Investigation of the Tensile Strength of Adhesive-Bonded Steels Using Surface Treatments

Zoltán Weltsch Miklós Berczeli Péter Kovács Benjámin Körömi

Publication Name: Materials

Publication Date: 2023-12-01

Volume: 16

Issue: 24

Page Range: Unknown

Description:

This study explores the tensile strength of adhesive joints in steel, focusing on the influence of heat treatment and diverse surface modifications. Results indicate a notable relationship between annealing temperature and tensile strength, with the most favorable outcomes identified at 90 min and 165 °C. Particularly, surfaces treated through turning, sandblasting, and plasma treatment (type C) consistently outperformed other methods. A standout revelation emerged from the turned, sandblasted, and plasma-treated surface (C), showcasing an exceptional tensile strength of 69.06 MPa. Load-holding tests underscored its resilience under diverse load conditions. Surface analyses, including roughness measurements, wetting characteristics, and Scanning Electron Microscope imaging, provided valuable insights into structural transformations induced by different treatments. Chemical composition examinations unveiled significant alterations post-plasma treatment, impacting surface chemistry and contributing to an outstanding tensile strength of 67.63 MPa. In essence, this research offers a glimpse into the nuanced factors influencing adhesive joint strength in steel. The turned, sandblasted, and plasma-treated surface emerges as a promising avenue, sparking further curiosity into the underlying mechanisms propelling superior tensile strength in adhesive joints.

Open Access: Yes

DOI: 10.3390/ma16247663

An extended stress-based forming limit diagram focusing on the wrinkling phenomenon and the effect of the normal pressure on clamped surfaces

Zoltán Weltsch Zsolt Lukács Gábor J. Béres Richárd Borbély Martin L. Kölüs Miklos Tisza

Publication Name: Journal of Materials Processing Technology

Publication Date: 2023-12-01

Volume: 322

Issue: Unknown

Page Range: Unknown

Description:

A novel wrinkling limit representation following the pattern of the conventional forming limit curves (FLCs) and the stress-based forming limit curves (SFLCs) as well as the application of the assumed criterion in finite element modelling are discussed in this manuscript. FLCs can partially refer to the wrinkling potential in the area left to the uniaxial tension line, but just like the SFLCs, cannot characterize the limits of the material behavior in a deeper sense, if negative in-plane stress and normal pressure act together on the sheet. This study predicts the wrinkling risk of clamped surfaces with a stress-based criterion through solving the analytical equations of the critical compressive stress causing wrinkling, and the corresponding blank holder pressure. The critical values were calculated based on the Wang and Cao's theory using Hill48 anisotropic yield function coupled with the Swift hardening law. The results draw a novel wrinkling limit curve representation methodology, in which the minor stress responsible for wrinkling and its ratio to the major stress are distinguished in the function of the applied blank holder pressure. The applicability of the calculated curves was investigated using finite element simulations, which showed that this method provides the opportunity to quantitatively interpret how close a component is to the wrinkling limit. The calculated wrinkling tendencies were verified by standard cup drawing tests supplemented by round shape error measurements on three different automotive steel sheets. It can be stated that the obtained numerical conditions of wrinkling were fitted to the experiments fairly well.

Open Access: Yes

DOI: 10.1016/j.jmatprotec.2023.118196

Crystallinity and Oscillatory Shear Rheology of Polyethylene Blends

Zoltán Weltsch Dorottya Nagy

Publication Name: Materials

Publication Date: 2023-10-01

Volume: 16

Issue: 19

Page Range: Unknown

Description:

Crystallinity and rheological behavior are significant for processing semi-crystalline polymers with fine mechanical properties. There is always an economical need to create a less expensive new material with better properties. Non-isothermal crystallization and oscillatory shear rheology of different branch-type polyethylene–polyethylene blends were investigated. Samples of high-density and low-density polyethylene (HDPE/LDPE) (20/80, 40/60, 60/40 and 80/20 weight ratios) and two types of high-density and linear low-density polyethylene (HDPE/LLDPE) (40/60 and 60/40 weight ratios) were prepared via extrusion. The materials were tested by differential scanning calorimetry (DSC) at several cooling rates (5, 10, 20, 30 and 40°/min) and by oscillation rheometry (ARES G2) at low angular frequency range to prove their miscibility or immiscibility. It was found that the one-peak melting endotherm of the 80–20% HDPE-LDPE blend could indicate miscibility in the solid phase, while the other HDPE-LDPE blends with two-peak curves are partially or not miscible. In contrast, all the HDPE-LLDPE blends indicate co-crystallization, but the 40–60% HDPE-LLDPE butylene blend is probably immiscible. It was revealed that complex viscosity decreases with angular frequency: linearly for HD-LD blends and not linearly for HD-LLDPE blends. The complex viscosity shows linear behavior with composition for HD-LLDPE blends, while there is a positive–negative deviation for HD-LD blends. In the liquid phase, according to rheological measurements, the HDPE-LDPE blends are not or partially miscible, while the HDPE-LLDPE blends are probably miscible.

Open Access: Yes

DOI: 10.3390/ma16196402

Workflow Development of AI Based Spectrogram Analysis with Real-time Out of Distribution Detection

Zoltán Weltsch Lóránt Szabó

Publication Name: Proceedings of the 2024 25th International Carpathian Control Conference Iccc 2024

Publication Date: 2024-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The aim of this paper is to investigate possible workflows for OOD pattern recognition in AI-based spectrogram analysis, applied in industrial manufacturing environment. First, we attempt to identify and articulate the challenges associated with OOD recognition in the context of spectrogram analysis, where the acoustic sources are subtle and often complex signals. These deserve particular attention, since the effectivity of OOD detection algorithms are acceptable in case of significant deviations, however, it is questionable for fine anomalies. In addition, it is also discussed here, how OOD records can affect the accuracy and reliability of AI models in terms of equipment failure identification and process inefficiencies. Last, methodes are proposed for OOD-pattern recognition. The integrability of these methods into existing manufacturing workflows in terms of practicality, adaptability and effectiveness are also investigated.

Open Access: Yes

DOI: 10.1109/ICCC62069.2024.10569262

Understanding and analyzing the effect of residual stresses in direct metal laser sintering through optical deformation measurement

Zoltán Weltsch István Hatos Valentin Szabó

Publication Name: Progress in Additive Manufacturing

Publication Date: 2025-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Residual stresses are one of the main challenges in metal additive manufacturing, particularly in direct metal laser sintering (DMLS). These stresses often lead to deformation once parts are removed from the build plate. In this study, we investigated the causal relationship between internal stresses and deformation behavior using a specially designed twin-cantilever geometry. This setup allowed parallel evaluation of different stress-relief treatments on a single component while minimizing cross-effects. High-precision optical 3D scanning was used to measure full-surface deformations before and after support removal and stress-relief heat treatment. The 1.2709 maraging steel (X3NiCoMoTi18-9-5) specimens were produced using a DMLS process with standard parameters, and stress-relief annealing was performed at 600 °C for 24 h. Results show that the heat treatment significantly reduced distortion on the supported side of the parts, with changes under 5%, while unsupported regions showed increased deformation, exceeding 60% in some cases. This indicates that internal stresses remain largely intact during heating and can further distort softened material if not mechanically constrained. The study confirms the critical role of constraint during heat treatment and demonstrates that optical metrology offers a reliable method to evaluate deformation trends. The results provide important insights into stress management strategies for DMLS parts and highlight the limitations of thermal relief in unconstrained geometries.

Open Access: Yes

DOI: 10.1007/s40964-025-01371-3