CRASHWORTHINESS DESIGN OF THE SHEAR BOLTS FOR LIGHT COLLISION SAFETY DEVICES

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5603-5608 ◽  
Author(s):  
JIN SUNG KIM ◽  
HOON HUH ◽  
TAE SOO KWON
Keyword(s):  
High Speed ◽  
Compressive Loading ◽  
Shear Loading ◽  
Crash Test ◽  
Main Body ◽  
Safety Devices ◽  
Dynamic Experiments ◽  
Collision Safety ◽  
Crashworthiness Design ◽  
Energy Absorbing

This paper introduces the jig set for the crash test and the crash test results of shear bolts which are designed to fail at train crash conditions. The tension and shear bolts are attached to Light Collision Safety Devices(LCSD) as a mechanical fuse when tension and shear bolts reach their failure load designed. The kinetic energy due to the crash is absorbed by the secondary energy absorbing device after LCSD are detached from the main body by the fracture of shear bolts. A single shear bolt was designed to fail at the load of 250 kN. The jig set designed to convert a compressive loading to a shear loading was installed to the high speed crash tester for dynamic shear tests. Two strain gauges were attached at the parallel section of the jig set to measure the load responses acting on the shear bolts. Crash tests were performed with a carrier whose mass was 250 kg and the initial speed of the carrier was 9 m/sec. From the quasi-static and dynamic experiments as well as the numerical analysis, the capacity of the shear bolts were accurately predicted for the crashworthiness design.

Crash Tests of Tension Bolts in Light Safety Collision Devices

2008 ◽  
Vol 385-387 ◽  
pp. 685-688 ◽  
Author(s):  
Jin Sung Kim ◽  
Hoon Huh ◽  
Won Mog Choi ◽  
Tae Soo Kwon
Keyword(s):  
High Speed ◽  
Failure Load ◽  
Compressive Loading ◽  
Crash Test ◽  
Test Results ◽  
Element Analysis ◽  
Load Response ◽  
Collision Safety ◽  
Energy Absorbing ◽  
Crash Tests

This paper demonstrates the jig set for the crash test and the crash test results of the tension bolts with respect to an applied pre-tension. The tension and shear bolts are adopted at Light Collision Safety Devices as a mechanical fuse when tension bolts reach designed failure load. The kinetic energy due to the crash is absorbed by secondary energy absorbing devices after the fracture of tension bolts. One tension bolt was designed to be failed at the load of 375 kN. The jig set was designed to convert a compressive loading to a tensile loading and installed at the high speed crash tester. The strain gauges were attached at the parallel section of the tension bolts to measure the level of the pre-tension acting on the tension bolts. Crash tests were performed with a barrier whose mass was 250 kg and initial speed of the barrier was 9.5 m/sec. The result includes the load response of the tension bolts during both the crash tests and finite element analysis.

New Energy-Absorbing High-Speed Safety Barrier

2003 ◽  
Vol 1851 (1) ◽  
pp. 53-64 ◽  
Author(s):  
John D. Reid ◽  
Ronald K. Faller ◽  
Jim C. Holloway ◽  
John R. Rohde ◽  
Dean L. Sicking
Keyword(s):  
High Speed ◽  
Steel Tube ◽  
Full Scale ◽  
Element Analysis ◽  
Dynamic Component ◽  
Testing Program ◽  
Roadside Safety ◽  
New Energy ◽  
University Of Nebraska Lincoln ◽  
Energy Absorbing

For many years, containment for errant racing vehicles traveling on oval speedways has been provided through rigid, concrete containment walls placed around the exterior of the track. However, accident experience has shown that serious injuries and fatalities may occur through vehicular impacts into these nondeformable barriers. Because of these injuries, the Indy Racing League and the Indianapolis Motor Speedway, later joined by the National Association for Stock Car Auto Racing (NASCAR), sponsored the development of a new barrier system by the Midwest Roadside Safety Facility at the University of Nebraska–Lincoln to improve the safety of drivers participating in automobile racing events. Several barrier prototypes were investigated and evaluated using both static and dynamic component testing, computer simulation modeling with LS-DYNA (a nonlinear finite element analysis code), and 20 full-scale vehicle crash tests. The full-scale crash testing program included bogie vehicles, small cars, and a full-size sedan, as well as Indy Racing League open-wheeled cars and NASCAR Winston Cup cars. A combination steel tube skin and foam energy-absorbing barrier system, referred to as the SAFER (steel and foam energy reduction) barrier, was successfully developed. Subsequently, the SAFER barrier was installed at the Indianapolis Motor Speedway in advance of the running of the 2002 Indianapolis 500 race. From the results of the laboratory testing program as well as analysis of the accidents into the SAFER barrier occurring during practice, qualification, and the race, the SAFER barrier has been shown to provide improved safety for drivers impacting the outer walls.

scholarly journals In situ damage assessment using synchrotron X-rays in materials loaded by a Hopkinson bar

2014 ◽  
Vol 372 (2015) ◽  
pp. 20130191 ◽  
Author(s):  
Weinong W. Chen ◽  
Matthew C. Hudspeth ◽  
Ben Claus ◽  
Niranjan D. Parab ◽  
John T. Black ◽  
...  
Keyword(s):  
High Speed ◽  
Particle Interaction ◽  
Tensile Failure ◽  
High Rate ◽  
X Rays ◽  
Contrast Imaging ◽  
X Ray ◽  
Damage Initiation ◽  
Dynamic Experiments

Split Hopkinson or Kolsky bars are common high-rate characterization tools for dynamic mechanical behaviour of materials. Stress–strain responses averaged over specimen volume are obtained as a function of strain rate. Specimen deformation histories can be monitored by high-speed imaging on the surface. It has not been possible to track the damage initiation and evolution during the dynamic deformation inside specimens except for a few transparent materials. In this study, we integrated Hopkinson compression/tension bars with high-speed X-ray imaging capabilities. The damage history in a dynamically deforming specimen was monitored in situ using synchrotron radiation via X-ray phase contrast imaging. The effectiveness of the novel union between these two powerful techniques, which opens a new angle for data acquisition in dynamic experiments, is demonstrated by a series of dynamic experiments on a variety of material systems, including particle interaction in granular materials, glass impact cracking, single crystal silicon tensile failure and ligament–bone junction damage.

Parametric study of a fibrous energy absorbing material under impact shear loading

2020 ◽  
Vol 232 ◽  
pp. 111583
Author(s):  
Jared Correia ◽  
Vijaya Chalivendra ◽  
Yong Kim
Keyword(s):  
Parametric Study ◽  
Shear Loading ◽  
Absorbing Material ◽  
Energy Absorbing

scholarly journals Strain rate and thermal softening effects in shear testing of AA7075-T6 sheet

2018 ◽  
Vol 183 ◽  
pp. 02037 ◽  
Author(s):  
Taamjeed Rahmaan ◽  
Ping Zhou ◽  
Cliff Butcher ◽  
Michael J. Worswick
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Rate Sensitivity ◽  
Thermal Conditions ◽  
Shear Loading ◽  
Image Correlation ◽  
High Rate ◽  
Strain Rates ◽  
Shear Testing ◽  
Plane Shear

Shear tests were performed at strain rates ranging from quasi-static (0.01 s-1) to 500 s-1 for AA7075-T6 sheet metal alloy at room temperature. A miniature sized shear specimen was used in this work to perform high strain rate shear testing. Digital image correlation (DIC) techniques were employed to measure the strains in the experiments. At maximum in-plane shear strains greater than 20%, the AA7075-T6 alloy demonstrated a reduced work hardening rate at elevated strain rates. At lower strains, the AA7075-T6 alloy showed mild positive rate sensitivity. The strain to localization (using the Zener-Holloman criterion), measured using the DIC technique, decreased with strain rate in shear loading. The strain at complete failure, however, exhibited an increase at the highest strain rate (500 s-1). The current work also focused on characterization of the thermal conditions occurring during high rate loading in shear with in situ high speed thermal imaging. Experimental results from the highest strain rate (500 s-1) tests showed a notable increase in temperature within the specimen gauge region as a result of the conversion of plastic deformation energy into heat.

Composite Core Cross Tube Crushing Analysis

2020 ◽  
Author(s):  
Sean Jenson ◽  
Muhammad Ali ◽  
Khairul Alam
Keyword(s):  
Energy Absorption ◽  
Compressive Loading ◽  
Deformation Mode ◽  
High Energy ◽  
Absorption Capacity ◽  
Functionally Graded ◽  
Layer By Layer ◽  
Thin Walled ◽  
The Cross ◽  
Energy Absorbing

Abstract Thin walled axial members are typically used in automobiles’ side and front chassis to improve crashworthiness of vehicles. Extensive work has been done in exploring energy absorbing characteristics of thin walled structural members under axial compressive loading. The present study is a continuation of the work presented earlier on evaluating the effects of inclusion of functionally graded cellular structures in thin walled members under axial compressive loading. A compact functionally graded composite cellular core was introduced inside a cross tube with side length and wall thickness of 25.4 mm and 3.048 mm, respectively. The parameters governing the energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, plateau stress level, and energy curves, were evaluated. The results showed that the inclusion of composite graded cellular structure increased the energy absorption capacity of the cross tube significantly. The composite graded structure underwent progressive stepwise, layer by layer, crushing mode and provided lateral stability to the cross tube thus delaying local tube wall collapse and promoting large localized folds on the tube’s periphery as compared to highly localized and compact deformation modes that were observed in the empty cross tube under axial compressive loading. The variation in deformation mode resulted in enhanced stiffness of the composite structure, and therefore, high energy absorption by the structure. This aspect has a potential to be exploited to improve the crashworthiness of automobile structures.

Energy-absorbing mechanisms and crashworthiness design of CFRP multi-cell structures

2020 ◽  
Vol 233 ◽  
pp. 111631 ◽  
Author(s):  
Guohua Zhu ◽  
Qiang Yu ◽  
Xuan Zhao ◽  
Lulu Wei ◽  
Hao Chen
Keyword(s):  
Cell Structures ◽  
Crashworthiness Design ◽  
Energy Absorbing

Large-scale drop test on perlite–metal syntactic foam

2018 ◽  
Vol 53 (4) ◽  
pp. 515-520 ◽  
Author(s):  
T Fiedler ◽  
M Taherishargh
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Low Cost ◽  
Syntactic Foam ◽  
Drop Test ◽  
Passenger Vehicle ◽  
High Speed Imaging ◽  
Cellular Metal ◽  
Energy Absorbing ◽  
Impact Mass

Perlite–metal syntactic foam is a low-cost cellular metal intended for use in automotive impact protection. To test the viability of the material a 2.5 ton drop test was conducted. Impact mass and energy were selected to replicate the conditions of a frontal impact between a large passenger vehicle and a crash cushion. A hollow syntactic foam cylinder was manufactured to decelerate the drop weight in a controlled manner. Accelerometers and high-speed imaging were utilized to evaluate the performance of the energy absorbing element.

Shear band characteristics in high strain rate naval applications

2019 ◽  
Author(s):  
Michael J. P. Conway ◽  
James D. Hogan
Keyword(s):  
High Speed ◽  
Dynamic Compression ◽  
Shear Banding ◽  
Shear Bands ◽  
Critical Time ◽  
Strain Rates ◽  
Static Case ◽  
Dynamic Experiments ◽  
Naval Steels ◽  
Strain Responses

Abstract This paper explores the dynamic behavior of HSLA 65 naval steels, specifically focusing on the initiation and growth of shear bands in quasi-static and dynamic compression experiments and how these bands affect stress-strain responses. The results indicate that the yield strength for this HSLA 65 increases from 541 ± 8 MPa for quasi-static (10-3 s-1) to 1081 ± 48 MPa for dynamic rates 1853 ± 31 s-1, and the hardening exponent increases from 0.376 ± 0.028 for quasi-static to 0.396 ± 0.006 for dynamic rates. Yield behavior was found to be associated with the onset of shear banding for both strain-rates, confirmed through visualization of the specimen surface using high-speed and ultra-high-speed cameras. For the quasi-static case, shear banding and yielding was observed to occur at 2.5% strain, and were observed to grow at speeds of upwards of 38 mm/s. For the dynamic experiments, the shear banding begins at approximately 1.18 ± 0.06% strain and these can grow upwards of 2122 ± 213 m/s during post-yield softening. Altogether, these measurements are some of the first of their kind in the open literature, and provide guidance on the critical time and length scales in shear banding. This information can be used in the future to design more failure-resistant steels, which has broader applications in construction, defense, and natural resource industries.

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