absorbing elements
Recently Published Documents


TOTAL DOCUMENTS

59
(FIVE YEARS 16)

H-INDEX

9
(FIVE YEARS 1)

Author(s):  
Karol Jaśkiewicz ◽  
Mateusz Skwarski ◽  
Paweł Kaczyński ◽  
Zbigniew Gronostajski ◽  
Sławomir Polak ◽  
...  

AbstractThe article covers experimental research on the forming of products made of 7075 aluminum alloy. This aluminum alloy grade is characterized by high strength, but due to its low formability in T6 temper, its use in the stamping processes of complex structural elements is limited. The authors have manufactured a U-shaped element at an elevated temperature and determined the optimal parameters of the process. Conventional heating of the sheet and shaping it at the temperature of 100 and 150 °C allowed to obtain a product of high strength similar to the T6 state, above 540 MPa. Due to the excessive springback of the sheet during forming, these products were characterized by a large deviation of the shape geometry, exceeding the allowable values of + / − 1 mm. Only the use of an alternative method of heating the sheet to temperatures of 200 and 240 °C (between plates at 350 °C, heating time 2 min, heating rate 1.8 °C/s) allowed to obtain a product that meets both the strength and geometric requirements. The determined optimal process’ parameters were later transferred to the stamping process of elements of a more complex shape (lower part of the B-pillar). The sheet was heated up and formed in the previously pre-heated tools. In the subsequent series of tests, the heating method and the blank’s temperature were being analyzed. In the case of the foot of the B-pillar, it was necessary to lower the initial blank temperature to 200 °C (heating in a furnace with a temperature of 340 °C, heating speed 0.5 °C/s). The appropriate combination of the process parameters resulted in the satisfactory shape deviation and reaching the product’s strength comparable to the strength of the material in as-delivered T6 temper. Using electron microscopy, it was verified that the structure of the finished product contained particles MgZn2 that strongly strengthen the alloy. The obtained results complement the data on the possibility of using 7075 aluminum alloy to produce energy-absorbing elements of motor vehicles.


2021 ◽  
Vol 2021 (4) ◽  
pp. 57-64
Author(s):  
Аnastasiya А. КОNОN ◽  

Objective: To outline the theoretical and methodological foundations of the railway track oscillation frequency analysis. To justify the need to assess the level of vibrodynamic impact of rolling stock on the elements of the track superstructure and the roadbed. To provide a methodology for calculating the oscillation parameters. To evaluate the effectiveness of the use of shock-absorbing elements. Methods: The modeling of the oscillatory process of the railway track elements and the analysis of physical models of oscillations were used. Results: The applicability of assessing the level of vibrodynamic impact of rolling stock on the elements of the track superstructure and the roadbed has been confirmed. A physical model of the vibrodynamic force impact of railway rolling stock and the responses of track infrastructure elements is described. The procedure for calculating the natural frequencies of the elements of the track superstructure and the roadbed and the characteristics of the shock-absorbing elements is given. Practical importance: The presented methods for calculating the natural frequencies of the elements of the track superstructure and the roadbed, as well as the characteristics of resilient shock-absorbing elements – rail shock pads and sleeper pads – make it possible to evaluate the effectiveness of their use to reduce the level of vibrodynamic impacts, to protect against resonance, and ensure the train traffic safety.


2021 ◽  
Vol 26 (6) ◽  
pp. 521-532
Author(s):  
A.V. Pilkevich ◽  
◽  
V.D. Sadkov ◽  

One of the urgent tasks in the design of hybrid integrated circuits (HIC) is the construction of adapter-attenuators – film absorbing elements providing a wide range of attenuations with specified values of input and output resistances. Known variants of adapter-attenuators based on a homogeneous and piecewise homogeneous resistive film provide (by introducing asymmetry in the dimensions of the input and output contacts, changing the location of a piecewise homogeneous resistive film, introducing dielectric or conductive regions) a resistance transformation coefficient of no more than 3 and 10–12, respectively. In this work, promising topologies of adapter-attenuators for HIC with a close to optimal profile of input and output contacts are proposed, which allow not only to obtain a wide range of transformation coefficients (more than 100), but also to reduce the maximum values of the potential gradient and power density by 10‒30 times. The rectangular topology calculations were made using the apparatus of the theory of functions of a complex variable. Modeling of the optimized topology of adapter-attenuators for HIC was carried out by the finite element method implemented in the Elcut software package. The calculated ratios and graphs showing the relationship of attenuation, the transformation coefficient, the gain in the value of the potential gradient and the power density, depending on the ratio of the size of the film element and the resistivity of the resistive films used, have been provided. The features of adapter-attenuators fitting have been considered. The results obtained are especially important for the pulse mode of operation of adapter-attenuators’ film element for HIC.


Author(s):  
Livia cristina cavalher atz de vilhena Moraes

The use of less impacting techniques in agricultural systems is the global trend, so the use of High dilutions on these systems has been studied as ecologically sound technology. This study had the object to study the interaction between the High dilutions and the development of Eucalyptus urophylla S. T. Blake seedlings. Was conducted from May 2007 to July 2007, in the greenhouse of the Department of Plant Science at the Federal University of Viçosa. Applications were made in one day intervals and preparations utilized were: Phosphorus, Calcarea carbonica, Kali muriaticum, Magnesia carbonica, in dynamizations 3CH and 12CH and water and alcohol dynamised CH3. Morphological parameters of quality seedlings were analyzed over time and the end of the experiment. The prepared Kali muriaticum 12CH promoted increased root length of approximately 55% compared to control water . The prepared Phosphorus 3CH differed from other treatments in the green total mass variable. The High dilutions Phosphorus 3CH and Kali muriaticum 12CH promoted increase in root growth. The responses obtained with the application of Phosphorus 3CH indicate the viability of agronomic use to the increase of the root exploration and absorbing elements necessary for plant growth.


Meccanica ◽  
2021 ◽  
Author(s):  
Krzysztof Kubas ◽  
Andrzej Harlecki

AbstractThe paper presents a certain method of analysing the dynamics of a belt transmission. A flat transmission model developed by us was presented. For the analysis, it assumed the transmission 5PK belt. A discrete belt model, being a system of rigid beams interconnected with flexible and shock-absorbing elements, was used. To account for the mutual influence between the belt and pulleys, the Kelvin–Voigt contact model was used. The GMS friction model was also implemented, which allows all basic known friction phenomena to be taken into account. For this purpose, the vector of generalized coordinates was expanded with additional sub-systems of coordinates modelling the flexible belt-pulley connection. Moreover, two additional cases of a sudden transmission start were presented: with values of driving and resistance torque not causing a significant slip in the transmission as well as values of torque that cause slip.


Author(s):  
Lech Starczewski ◽  
Krzysztof Szcześniak ◽  
Michał Gmitrzuk ◽  
Robert Nyc

The paper presents the results of a study to determine the degree of attenuation of a detonation wave pulse generated by a spherical ceresin-phlegmatized hexogen charge, by spaced material systems. The systems were mounted on a ballistic pendulum and the amount of energy absorbed was determined based on the change in pendulum swing. The spaced panels with absorbing elements, simulated the flat bottom of a vehicle exposed to a single blast.


2020 ◽  
Vol 4 (OOPSLA) ◽  
pp. 1-28
Author(s):  
Guilherme Vieira Leobas ◽  
Fernando Magno Quintão Pereira
Keyword(s):  

2020 ◽  
Vol 101 (1) ◽  
pp. 37-50
Author(s):  
Barbora Batíková ◽  
Tomáš Kepka ◽  
Petr Němec
Keyword(s):  

Author(s):  
Hongtao Liu ◽  
Jianran Wang ◽  
Xiaofang Liu ◽  
Kefei Wang ◽  
Qi Luo ◽  
...  

Abstract Collision posts have been required at the front end of railway vehicles to provide protection against intrusion under collision in the US market since 1940s, though it is still not a standard required structure in the Europe and Asia markets. In this paper, typical front-end frame with and without collision posts of railway vehicles are compared to illustrate the pros and cons of collision posts in railway vehicles. Then two different front-end frames with collision posts are introduced in detail to discuss how to take the advantages of collision posts and avoid the drawbacks in different applications. In the first design, the collision posts are placed in front of the energy absorbing elements. When collision happens, the collision posts will deform first before the energy absorbing elements act. As a result, the collision posts and many carbody and cab structures, such as the front-end frame, underframe, cab interior and operator console may under repair even the collision speed is low. However, more space can be utilized for the cab and passenger compartment since the collision posts can be located at the very front of the vehicle. In the second design, there are two stages of energy absorbing elements and the collision posts are placed in the middle. The first stage of energy absorbing elements can absorb low-speed collision energy without damaging other structures and can be replaced easily. To make up for the extra space taken by the first stage energy absorbing elements, the shape and dimension of the collision posts have to be optimized. For both designs, finite element analysis has been used to analyze and optimize the design. Then full-scale test specimens are manufactured and tested to further validate the design and analysis. Based on the design, analysis and test results, an overall evaluation of collision post’s role in passenger protection and vehicle design has been generated.


Sign in / Sign up

Export Citation Format

Share Document