Search in Publications

Found 6319 publications

Preparation and characterization of poly(lactic acid)/boehmite alumina composites for additive manufacturing

Imre Fekete László Lendvai

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2020-08-25

Volume: 903

Issue: 1

Page Range: Unknown

Description:

The purpose of this work is to investigate the suitability of boehmite alumina (BA) reinforced poly(lactic acid) (PLA) for additive manufacturing with the fused filament fabrication method. PLA filaments with 0-10 wt.% BA content were produced via melt compounding using a twin-screw extruder. Dumbbell-shaped and prismatic specimens were manufactured then by feeding the prepared filaments into a desktop 3D printer. Mechanical, morphological and melt flow properties of the developed samples were determined. The addition of BA decreased the melt flow rate of PLA, however not so much that it would have hindered its suitability for 3D printing. With increasing BA content both the strength and the stiffness of the samples increased slightly at constant deformability and toughness. Scanning electron microscopic images revealed a homogenous dispersion of BA particles within the PLA matrix, although remaining agglomerates were also observed.

Open Access: Yes

DOI: 10.1088/1757-899X/903/1/012057

Methods for improving the mid-frequency acoustic simulation of a lightly damped plate

Dániel Feszty Marcell Treszkai Tamas Turcsik Janos Kun

Publication Name: Proceedings of 2020 International Congress on Noise Control Engineering Inter Noise 2020

Publication Date: 2020-08-23

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The constantly evolving customer demands in the automotive industry necessitates vehicle manufacturers to perform ever more accurate acoustic simulations. Acoustic simulations especially in the mid-frequency range (400 Hz - 1000 Hz) pose particular challenges: statistical methods lack the necessary modal density for accuracy, while Finite Element Methods (FEM) have difficulty accounting for statistical effects. In order to resolve the conflict that FEM solvers face, an academic case is investigated. A flat plate of 650x 750 mm in free-free condition is examined as a low-complexity platform to investigate the sensitivity of FEM simulation results to parameters, such as the value of structural damping, the frequency dependency of structural damping as well as the variations in the plate thickness due to manufacturing tolerances. FEM simulations were performed using ESI VPS and compared to measurements. Results show that slight variations in plate thickness and Young`s modulus can have significant impact on the frequency response. Results have shown that a 0.5% variation in the thickness already has a pronounced effect on frequency response peak locations, especially between 600 and 1000 Hz. Beside this, the paper provides novel results on evaluating the effects of frequency dependency of structural damping on the results.

Open Access: Yes

DOI: DOI not available

Methods for improving the mid-frequency acoustic simulation of a lightly damped plate

No authors available

Publication Name: Proceedings of 2020 International Congress on Noise Control Engineering, INTER-NOISE 2020

Publication Date: 2020-08-23

Volume:

Issue:

Page Range: Unknown

Description:

The constantly evolving customer demands in the automotive industry necessitates vehicle manufacturers to perform ever more accurate acoustic simulations. Acoustic simulations especially in the mid-frequency range (400 Hz - 1000 Hz) pose particular challenges: statistical methods lack the necessary modal density for accuracy, while Finite Element Methods (FEM) have difficulty accounting for statistical effects. In order to resolve the conflict that FEM solvers face, an academic case is investigated. A flat plate of 650x 750 mm in free-free condition is examined as a low-complexity platform to investigate the sensitivity of FEM simulation results to parameters, such as the value of structural damping, the frequency dependency of structural damping as well as the variations in the plate thickness due to manufacturing tolerances. FEM simulations were performed using ESI VPS and compared to measurements. Results show that slight variations in plate thickness and Young`s modulus can have significant impact on the frequency response. Results have shown that a 0.5% variation in the thickness already has a pronounced effect on frequency response peak locations, especially between 600 and 1000 Hz. Beside this, the paper provides novel results on evaluating the effects of frequency dependency of structural damping on the results.

Open Access: No

DOI: DOI not available

Design of acoustic cavity test apparatus for validation of mid-frequency response of a plate-cavity system

No authors available

Publication Name: Proceedings of 2020 International Congress on Noise Control Engineering, INTER-NOISE 2020

Publication Date: 2020-08-23

Volume:

Issue:

Page Range: Unknown

Description:

The mid-frequency range acoustic response between 400-1000 Hz has gained particular interest in the automotive industry recently. Simulation of this region is challenging due to the non-negligible statistical effects, especially when acoustic trim is applied. In order to be able to investigate the effect of these materials in the presence of an air cavity, this paper describes the design methodology behind the design and manufacturing of two test apparatuses that include an air cavity. The apparatuses were designed to serve as a validation tool for Finite Element Method (FEM) and Statistical Energy Analysis (SEA) simulations, which meant that an optimal size had to be found based on the number of fluid modes in the cavity. Two types of plate-cavity apparatuses have been designed: one with “rigid walls” and one with “soft walls”. In the “rigid wall” cavity, the walls are made out of concrete since these boundary conditions can be perfectly represented in simulations. In the “soft wall” cavity, the walls are made of steel plates and this allows validation of coupling loss simulations between multiple structural subsystems as well as an air cavity. Details of the joining methods, geometries, material selections are elaborated to fully describe the theoretical and practical implications of the designs.

Open Access: No

DOI: DOI not available

Design of acoustic cavity test apparatus for validation of mid-frequency response of a plate-cavity system

Dániel Feszty Tamas Turcsik Janos Kun

Publication Name: Proceedings of 2020 International Congress on Noise Control Engineering Inter Noise 2020

Publication Date: 2020-08-23

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

The mid-frequency range acoustic response between 400-1000 Hz has gained particular interest in the automotive industry recently. Simulation of this region is challenging due to the non-negligible statistical effects, especially when acoustic trim is applied. In order to be able to investigate the effect of these materials in the presence of an air cavity, this paper describes the design methodology behind the design and manufacturing of two test apparatuses that include an air cavity. The apparatuses were designed to serve as a validation tool for Finite Element Method (FEM) and Statistical Energy Analysis (SEA) simulations, which meant that an optimal size had to be found based on the number of fluid modes in the cavity. Two types of plate-cavity apparatuses have been designed: one with “rigid walls” and one with “soft walls”. In the “rigid wall” cavity, the walls are made out of concrete since these boundary conditions can be perfectly represented in simulations. In the “soft wall” cavity, the walls are made of steel plates and this allows validation of coupling loss simulations between multiple structural subsystems as well as an air cavity. Details of the joining methods, geometries, material selections are elaborated to fully describe the theoretical and practical implications of the designs.

Open Access: Yes

DOI: DOI not available

Technology jump in the industry: human–robot cooperation in production

Zoltan Dobra Krishna S. Dhir

Publication Name: Industrial Robot

Publication Date: 2020-08-18

Volume: 47

Issue: 5

Page Range: 757-775

Description:

Purpose: Recent years have seen a technological change, Industry 4.0, in the manufacturing industry. Human–robot cooperation, a new application, is increasing and facilitating collaboration without fences, cages or any kind of separation. The purpose of the paper is to review mainstream academic publications to evaluate the current status of human–robot cooperation and identify potential areas of further research. Design/methodology/approach: A systematic literature review is offered that searches, appraises, synthetizes and analyses relevant works. Findings: The authors report the prevailing status of human–robot collaboration, human factors, complexity/ programming, safety, collision avoidance, instructing the robot system and other aspects of human–robot collaboration. Practical implications: This paper identifies new directions and potential research in practice of human–robot collaboration, such as measuring the degree of collaboration, integrating human–robot cooperation into teamwork theories, effective functional relocation of the robot and product design for human robot collaboration. Originality/value: This paper will be useful for three cohorts of readers, namely, the manufacturers who require a baseline for development and deployment of robots; users of robots-seeking manufacturing advantage and researchers looking for new directions for further exploration of human–machine collaboration.

Open Access: Yes

DOI: 10.1108/IR-02-2020-0039

Modal analysis of the tubular space frame of a formula student race car

Dániel Feszty Balázs Vehovszky Attila Schweighardt

Publication Name: Manufacturing Technology

Publication Date: 2020-08-06

Volume: 20

Issue: 1

Page Range: 84-91

Description:

This document presents the characterization of the dynamic mechanical properties of a racecar's frame. First, it introduces the applicability of modal analysis, then the modal analysis of a lightweight vehicle chassis will be detailed, which is the focal point of this paper. This analysis was performed to determine some of the modal parameters, in order to reduce the noise of the vehicle, the probability of a component failure and to improve the comfort. The simulation part of the applied analysis was based on dynamic FEM (Finite Element Method). The measurement part of it was based on measuring the FRFs (Frequency Response Functions), with the help of accelerometers fixed at the nodes of the frame. The excitation signals were provided by a shaker connected to the chassis. In order to provide good quality results, the processing and evaluation of the simulated and measured data has to be done properly, which is discussed in detail. However, one dominant factor of a modal analysis is to find the optimal measurement setup. For this reason, the details of the measurement setup will be included. Hence one of the goals was to improve the coherence curves of the FRFs. Thanks to the presented techniques, the coherence curves managed to be improved and the results of the simulation and the measurement were found to be in good agreement.

Open Access: Yes

DOI: 10.21062/mft.2020.013

Review of supply chain integration between 2000 and 2019:Analysis of current status and future trends

Zoltan Szegedi Gizem Erboz

Publication Name: International Journal of Supply Chain Management

Publication Date: 2020-08-01

Volume: 9

Issue: 4

Page Range: 43-51

Description:

Supply Chain Integration (SCI) integrates the activities between a firm and its channel members; therefore, it is a significant interdisciplinary subject for Supply Chain Management. The main aim of this paper is to review previous research on SCI in main academic sources to give some insights and practical information in the field of SCI, while indicating an overview of the main definitions, descriptive analysis and key themes of the selected studies. This paper refers from 115 research articles in 28 journals from main academic sources between 2000 and 2019. The main result of this study shows that in the last years, research interest in SCI has increased. Although there is a huge geographic dispersion on published studies, the USA holds a leading position on SCI publications. It has been identified that scholars mainly are looking for relationship between SCI and performance issues; in addition, new themes emerge such as the implementation of Information Technology (IT) in order to have better-integrated Supply Chains. By considering the complexities of Supply Chains, this research contributes to the literature on the ways of analyzing new trends and geographical dispersion as well as identifying the key themes in the context of SCI.

Open Access: Yes

DOI: DOI not available

Are collision and crossing course surrogate safety indicators transferable? A probability based approach using extreme value theory

Haneen Farah Marjan Hagenzieker Aliaksei Laureshyn Attila Borsos

Publication Name: Accident Analysis and Prevention

Publication Date: 2020-08-01

Volume: 143

Issue: Unknown

Page Range: Unknown

Description:

In order to overcome the shortcomings of crash data a number of surrogate measures of safety have been developed and proposed by various researchers. One of the most widely used temporal indicators is time-to-collision (TTC) which requires the road users to be on a collision course. Road users that are strictly speaking not on a collision course actually might behave and take evasive actions as if they were, thus indicating that such near-miss situations might also be relevant for safety analysis. Taking that into account, a more flexible indicator T2, which does not require the two vehicles to be on a collision course, describes the expected time for the second road user to arrive at the conflict point. Recently extreme value theory (EVT) offering two approaches, block maxima (BM) and Peak over Threshold (POT), has been applied in combination with surrogate indicators to estimate crash probabilities. Most of this research has focused on testing BM and POT as well as validating various surrogate safety indicators by comparing model estimates to actual crash frequencies. The comparison of collision course indicators with indicators including crossing course interactions and their performance using EVT has not been investigated yet. In this study we are seeking answers to under what conditions these indicators perform better and whether they are transferable. Using data gathered at a signalized intersection focusing on left-turning and straight moving vehicle interactions our analysis concluded that the two indicators are transferable with stricter threshold values for T2 and that POT gives more reasonable results.

Open Access: Yes

DOI: 10.1016/j.aap.2020.105517