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Finite Element Simulations of Impact Test for Light Alloy Wheels
(Izmir Institute of Technology, 2016) Pehlivanoğlu, Uğur; Yardımoğlu, Bülent
Static and dynamic finite element models for the simulation of the wheel impact test defined in ISO7141 were developed for the AlSi7Mg and AlSi11Mg alloy wheels. The dynamic model consists of the striker, the wheel with radial pneumatic tire, and the hub adapter structure. Two types of tire models, composite and simplified, are formed in this study. The finite element model in the dynamic model, referred to as composite tire, involves bead, bead core, casing and crown plies, tread, and side walls. A simplified tire model that does not include bead cores, casing and crown plies is also generated. Although these items are not used in the second model directly, they are considered using their equivalent effects. It is shown that a simplified tire model can be used instead of the composite tire model. The dynamic model is validated by experimental studies. Such studies are related to the plastic deformations at the impact point of the wheel. It is shown that simulation of the failure of the wheel during impact tests can be determined using von Mises and effective plastic strain occurs in the wheel. In total, forty-one experiments are done to see the wheel behaviors and whether it performes according to the standard. The experimental results and the corresponding simulations focusing on von Mises stresses along with effective strains are shown in box plots. Thus, critical values for design are found. The static model consists of the wheel with simplified tire and the lumped model of the hub adapter structure. The stiffness characteristic of the impact point of the wheel is determined by using the static model. It is shown that the maximum von Mises stress that occurs in the wheel due to impact load is found using energy conversions. Significant time can be saved by this manner.
Experimental and Numerical Investigation of the Quasi-Static and High Strain Rate Crushing Behavior of Single and Multi-Layer Zig-Zag 1050 H14 Al Trapezoidal Corrugated Core Sandwich Structures
(Izmir Institute of Technology, 2014) Kılıçaslan, Cenk; Güden, Mustafa; Taşdemirci, Alper; Güden, Mustafa; Taşdemirci, Alper
The quasi-static and dynamic crushing behavior of single, double and multi-layer zig-zag 1050 H14 Al trapezoidal corrugated core sandwich structures in 0°/0° and 0°/90° core orientations and with and without interlayer sheets were investigated both experimentally and numerically at varying impact velocities. The numerical simulations were conducted using the finite element code of LS-DYNA. The effect of fin wall imperfection was assessed through the fin wall bending and bulging. The numerical homogenization of the single layer corrugated structure was performed using MAT26 honeycomb material model. The buckling stress of single- and double-layer corrugated sandwich structures increased when the strain rate increased. The increased buckling stresses were ascribed to the micro inertial effects. The initial buckling stress at quasi-static and high strain rate was numerically shown to be imperfection sensitive. Increasing the number of core layers decreased the buckling stress and increased the densification strain. The panels tested with spherical and flat striker tips were not penetrated and experienced slightly higher deformation forces and energy absorptions in 0°/90° corrugated layer orientation than in 0°/0° orientation. However, the panels tested using a conical striker tip were penetrated/perforated and showed comparably smaller deformation forces and energy absorptions, especially in 0°/90° layer orientation. The homogenized models predicted the low velocity compression /indentation and projectile impact tests of the multi-layer corrugated sandwich with an acceptable accuracy with reduced computational time.

Phd Degree / Doktora

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