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Journal Article

Experimental Study of the Plasticity Responses of TRIP780 Steel Subjected to Strain-Path Changes

2016-04-05
2016-01-0363
The work-hardening response of TRIP780 steel subjected to strain-path changes was investigated using two-stage tension experiments. Large specimens were prestrained and then sub-sized samples were subjected to tension along various directions. The influence of strain-path changes on flow stress and work hardening performance was discussed in detail. The specific plastic work was calculated to compare the kinematic hardening behaviour after strain-path changes. The results showed that transient hardening was observed for TRIP780 sheets subjected to orthogonal strain-path change. The strain-hardening exponent (n-value) was influenced by prestraining levels and the strain path. The n-value exhibited a greater decrease under an orthogonal strain-path change. Prestraining can delay the onset of high work hardenability of TRIP steels. It is meaningful for the safety design of vehicles.
Technical Paper

Numerical Simulation of CFRP Thin-Walled Tubes Subjected to Quasi-Static Axial Crushing

2017-03-28
2017-01-0465
Carbon Fiber Reinforced Plastic (CFRP) tube is an important material for the lightweight design of automotive structures. Simulation method of CFRP thin-walled tubes subjected to axial compression using MAT54 in LS-DYNA was investigated. Based on the two-layer shell model combined with MAT54, failure strategy and the parameters sensitivity of the model were discussed in detail. Then the simulation model was verified by using duplicate specimens comprised of carbon fiber/epoxy unidirectional prepreg tape. Furthermore, the modeling methods of crush trigger and different types of loading speed were analyzed. In addition, based on the method of equal energy absorption, energy absorption performance of thin-walled circular and square tubes made from four materials including mild steel, high strength steel, aluminum alloy and CFRP were also compared.
Technical Paper

Research and 3-Dimensional Numerical Simulation about Internal Air Transient Flow Process and Air Flow-Induced Noise of Engine Electronic Control Throttle Quick-Opening Process

2018-04-03
2018-01-0470
Based on the basic structure and operating function of engine throttle, according to the actual structure of throttle, a 3-dimensional air transient flow is simulated to realize throttle rotated from closed position to opened position by using CFD moving mesh technology and user defined program. By applying CFD and CAA coupling method, the influence of the movement of throttle on air flow and flow-induced noise process are studied, the transient opening process is studied and analyzed. The velocity field, pressure field and the principle of flow-induced noise are analyzed under different rotational angle velocity of throttle.
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