Experimental and Numerical Study on Crashworthiness Parameters of Mild Steel Square Tube under Quasi-Static Axial Compression

In the present research, an experimental and numerical study on the crush response of square tube is presented. The explicit Finite Element Analysis (FEA) in LS-DYNA software is carried out to simulate crash behaviour under the quasi-static test conditions. Compression load is applied quasi-statically in an experimental study on the square tube specimens using Universal Testing Machine (UTM). In quasi-static test the bottom platen speed used is 1 mm/min. From experimental testing symmetric collapse mode is observed in all deformed specimens. The development of the symmetric collapse mode in a Finite Element (FE) model is also observed. Thus fold formation and crush response predicted by FE analysis are observed to be in very good correlation with the results obtained from experimental testing. Furthermore, the effect of the thickness of tube on crashworthiness parameters is investigated. From the FE analysis, it is found that the thickness of the square tube influences significantly the crashworthiness parameters.

Effects of Geometry, Triggering and Foam-Filling on Crashworthiness Behaviour of a Cylindrical Composite Crash Box

Crash boxes play an important role in different industries as energy absorbers to reduce damage of accidents. An ideal crash box has lower maximum force and higher energy absorption. The aim of this study is to investigate the effect of various parameters such as geometry (diameter and thickness), triggering and filling with polymeric foam on axial crash behaviour of a composite cylindrical cash box. To this end, a composite crash box is modelled in a commercial finite element software, Abaqus, utilising the Hashin failure criterion to predict damage initiation. Linking damage initiation with material degradation rules provides the capability for damage evolution prediction on the basis of fracture energy of different failure modes. A new parameter (β) is defined to study the performance of a crash box with different geometries, triggers and foam-filling. The results show that three different triggering geometries (chamfer, fillet, and tulip) decrease the maximum load about 7-33%, and improved energy absorption about 40-86% compared to the crash box without trigger. Filling a triggered crash box with polymeric foam also improves energy absorption about 20%. Applying both triggering and foam-filling simultaneously on a crash box has a complementary role to receive a better performance.

Comparison of Energy Absorption in Circular Aluminium Crash Boxes with Rigid and Elastic Boundary Conditions: Numerical and Experimental Investigations

Crash boxes are usually used in the transportation and automobile industries. Important parameters such as material, boundary conditions, geometry, impact energy consists of striker mass and velocity, and plastic deformation history can influence on the maximum energy absorption and impact load of these structures. In this research first, crash behaviour of extruded aluminium circular tubes under axial impact loading with rigid and elastic boundary conditions are studied. Then, effect of the elastic support on the tube energy absorption is numerically and experimentally investigated. In the following, the numerical results are compared with the practical observations and validated. Finally, it is revealed that employing the elastic support leads to changing deformation mode and significantly reduces the maximum impact load.

Simulation Methodology for Occupant Safety Assessment of Indian Railway Passenger Coach

This work intends to lay the groundwork for Computer Aided Engineering (CAE)-based occupant safety of a typical tier-III Indian Railway (IR) passenger coach in a collision accident. Our previous work presented in International Crashworthiness Conference 2010 under the title “Simulation of Crash Behaviour of a Common Indian Railway Passenger Coach” provided crashworthiness assessment of a typical tier-III passenger coach structure for representative head-on collision scenarios namely, against an identical passenger coach and against a stationary locomotive. These scenarios were envisioned to be part of a bigger accident scenario e.g - head-on collision between two trains moving towards each other. Analysis of involved chain of events for entire rolling stock and resulting internal collisions between individual passenger cars was out of scope of this work and necessary inputs were obtained from available literature on the same. This work used a full scale Finite Element (FE) simulation model and commercial explicit solver LS-Dyna. FE model was validated using International Railway Union (UIC) code OR566 specified proof loads for design. Simulation methodology used for dynamic impact was validated by component level crushing experiments using a drop tower facility. Material modelling incorporated strain rate effect on yield strength which is essential for obtaining accurate structural deformations under dynamic impact loading. Contacts were modelled using the penalty method option provided by the solver. This model was simulated for collisions at 30, 40 and 56 km/h against a stationary rigid barrier. Collision speeds were chosen to simulate impact energies involved in collision scenarios as mentioned above. The structure was found to exhibit global bending deformation and jackknifing with pivot position at the door section. In this paper, we present an extension of this work — coupled occupant safety simulation and injury assessment. It was accomplished by recording head, neck, chest and knee responses of a Hybrid-III 50th percentile male Anthropomorphic Test Device (ATD) FE model, seated in passenger position on lower berth of the first cabin of a passenger car. Interiors were modelled to represent the actual structure. Dummy model was adapted to passenger cabin’s excessive mobility conditions and responses were revalidated against Federal Motor Vehicle Safety Standards (FMVSS) limits. Injury interpretation was based on Abbreviated Injury Scale (AIS), automotive injury criteria and injury risk curves for Head Injury Criterion (HIC), thoracic spine acceleration, neck bending moment in flexion and extension and knee force. This study provides with estimates of injury and fatality based on computer simulation of accident scenarios. However, attempts of correlating to any available injury and fatality statistics were out of scope of this study.