Effect Of Damage Based Residual Strain From Preceding Draw Forming Processes In Crash Analysis

Halim, Mohd Faizal and Abu Shah, Ismail and Tamin, Mohd Nasir and Sulaiman, Saiful Naim and Samekto, Haryanti (2017) Effect Of Damage Based Residual Strain From Preceding Draw Forming Processes In Crash Analysis. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

The importance of considering residual strain in crash analysis has increased interest among researchers. However until now the influence of metal forming history in crash analysis is only based on residual strain of work hardening of large strain deformation. It is insufficient because at some extent the plastic strain has surpassed the onset of damage into the localized deformation that cannot be measured by FLD. At this point, the simulated draw forming cup parts mapped with different amount of residual strain compared to the purely large plastic deformed cup. An 80 mm diameter Dual Phase automotive steel blank is draw formed into cup shape parts using draw forming fixture actuated by testing machine at 500 mm/min loading. The 100 kN blank holding force is facilitated by hydraulic cylinder throughout the draw forming process. The subsequent process of crash analysis is conducted at 500 mm/min and 50 km/h of loading. In the FE simulation, the 3D draw forming model is simulated using piece-wise material hardening coupled with ductile damage criteria to replicate the onset of damage. Through try and error approach the fracture strain value at 0.6 give most approximate result on forming failure at drawn dept of 11.4mm and 119kN. Thus, the residual strain, stress and thickness distribution from forming result with damage criteria was mapped into crash model via result mapper. The crash analysis was conducted at quasi static loading of 500mm/min and dynamic loading of 50 km/h. The result of crash response mapped with all pre history forming forming residual without damage model shows similar pattern of load displacement response when compare with crash cup experimental result. Yet, the simulated crash response was recorded at 180kN higher than experimental result. On the other hand, the presenting damage model in mapped forming history into crash model give better prediction response on crash result. The reaction force of cup model was estimated at 100kN in both simulation and experimental crash analysis. Therefore, it was clearly indicated that JC damage model is very potential to be adopted in crash simulation to give better accuracy.

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