Damage Simulation of Stitched CFRP Laminates Under High-Velocity Projectile Impact

2015 ◽  
Author(s):  
Akinori Yoshimura ◽  
Yasuhito Mikami ◽  
Masahiro Nakayama ◽  
Toshio Ogasawara ◽  
Naoyuki Watanabe
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
High Velocity ◽  
Element Model ◽  
Bottom Surface ◽  
Damage Behavior ◽  
Cfrp Laminates ◽  
Non Linear ◽  
Linear Spring ◽  
Simulation Results

In this study, numerical analytical model which simulates the damage behavior of the through-the-thickness stitched CFRP laminates under high velocity impact (HVI) is developed. The simulation results are compared with experimental results for validation of the developed model. Through-the-thickness stitched CFRP laminates have good mechanical properties such as higher delamination toughness and better impact resistance than that of conventional laminates. In this study, rigid body impact tests were conducted for the stitched CFRP laminates. Test results revealed that through-the-thickness stitching effectively suppressed the propagation of the delamination, and it increased the performance against the perforation. Among them, moderate stitched CFRP had the highest performance. In order to analyze the HVI damage behavior of the stitched CFRP laminate, special finite element model was developed. In the model, the in-plane tensile and compressive fiber damages were considered by using stress criterion. Transverse cracks were modeled by continuum damage mechanics (CDM). Delamination was modeled by cohesive zone model (CZM). The effect of the stitch threads were introduced by multiscale approach. Out-of-plane tensile tests were performed for small specimens those include single stitching. Small finite element model which contains a non-linear spring element was prepared, and the load-displacement relationship of the non-linear spring was decided so that the result of the model agreed with the tests. Then, the spring elements were introduced to the HVI simulation model. The simulation results revealed that stitching bridges the delamination and delamination area was reduced. On the other hand, the simulation results revealed that delamination reduces the tensile stress in the bottom surface of the laminate. Because delamination easily propagate in the moderate stitched laminates, the performance against the perforation of the moderate stitched laminates is the highest among the stitched laminates.

scholarly journals Investigation of the Thickness Differential on the Formability of Aluminum Tailor Welded Blanks

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 875
Author(s):  
Jie Wu ◽  
Yuri Hovanski ◽  
Michael Miles
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Numerical Model ◽  
Plastic Strain ◽  
Finite Element Model ◽  
Equivalent Plastic Strain ◽  
Element Model ◽  
Dome Height ◽  
Tailor Welded Blanks ◽  
Simulation Results

A finite element model is proposed to investigate the effect of thickness differential on Limiting Dome Height (LDH) testing of aluminum tailor-welded blanks. The numerical model is validated via comparison of the equivalent plastic strain and displacement distribution between the simulation results and the experimental data. The normalized equivalent plastic strain and normalized LDH values are proposed as a means of quantifying the influence of thickness differential for a variety of different ratios. Increasing thickness differential was found to decrease the normalized equivalent plastic strain and normalized LDH values, this providing an evaluation of blank formability.

scholarly journals Reconstruction finite element model of cars

2021 ◽  
Vol 4 (1) ◽  
pp. first
Author(s):  
Lý Hùng Anh ◽  
Nguyễn Phụ Thượng Lưu ◽  
Nguyễn Thiên Phú ◽  
Trần Đình Nhật
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Finite Element Models ◽  
Crash Analysis ◽  
Inertia Moment ◽  
Frontal Crash ◽  
Analysis Center ◽  
Simulation Results ◽  
And Behavior

The experimental method used in a frontal crash of cars costs much time and expense. Therefore, numerical simulation in crashworthiness is widely applied in the world. The completed car models contain a lot of parts which provided complicated structure, especially the rear of car models do not contribute to behavior of frontal crash which usually evaluates injuries of pedestrian or motorcyclist. In order to save time and resources, a simplification of the car models for research simulations is essential with the goal of reducing approximately 50% of car model elements and nodes. This study aims to construct the finite element models of front structures of vehicle based on the original finite element models. Those new car models must be maintained important values such as mass and center of gravity position. By using condition boundaries, inertia moment is kept unchanged on new model. The original car models, which are provided by the National Crash Analysis Center (NCAC), validated by using results from experimental crash tests. The modified (simplistic) vehicle FE models are validated by comparing simulation results with experimental data and simulation results of the original vehicle finite element models. LS-Dyna software provides convenient tools and very strong to modify finite element model. There are six car models reconstructed in this research, including 1 Pick-up, 2 SUV and 3 Sedan. Because car models were not the main object to evaluate in a crash, energy and behavior of frontal part have the most important role. As a result, six simplified car models gave reasonable outcomes and reduced significantly the number of nodes and elements. Therefore, the simulation time is also reduced a lot. Simplified car models can be applied to the upcoming frontal simulations.

ESTABLISHMENT AND APPLICATION OF LOWER LIMB FINITE ELEMENT MODEL BASED ON MUSCLE GROUPS

2018 ◽  
Vol 18 (08) ◽  
pp. 1840024
Author(s):  
MONAN WANG ◽  
RONGPENG LI ◽  
JUNTONG JING
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Finite Element Model ◽  
Lower Limb ◽  
Element Model ◽  
Upper And Lower Bounds ◽  
Three Point Bending ◽  
Living Body ◽  
Prosthetic Socket ◽  
Simulation Results

Living body or corpse could be replaced with the virtual human tissue model for biomechanical experimental study, which effectively avoids the non-reusability, great social controversy, huge costs and difficulty in extracting parameters, and finally, the accurate analysis results are obtained. Unlike the previous lower limb models, the finite element models of hip and thigh were established based on the concept of muscle group in this paper. The cortical bones of hip bone and femur were set as *MAT_PIECEWISE_LINEAR_ PLASTICITY. The material of cancellous bone was set as *MAT_ELASTIC_PLASTIC_ WITH_DAMAGE_FAILURE. The material of articular cartilage was set as *MAT_ISOTROPIC_ELASTIC. The materials of muscle and fat were set as *MAT_VISCOELASTIC. The accuracy of the finite element model was verified by dynamic three-point bending experiment of the thighs. Mechanical simulation was carried out to the stump-prosthetic socket and the comfort of socks by the established model. The simulation results were all between the upper and lower bounds of the experimental results in the dynamic three-point bending experiment of the thighs where the loads were separately applied to one-third of the distal end of thighs and the middle part of thighs. The simulation results of the stump-prosthetic socket example show that the optimal elastic modulus of silicone pad is 2.5[Formula: see text]MPa. Simulation results of socks comfort show that the distribution of stress and deformation of the anterior and posterior thighs is different when the human lower limbs are in stockings. The established simulation model meets the accuracy requirement and can replace the living body or corpse to carry out biomechanical experimental study. The finite element simulation results converge, and the time to complete a finite element calculation is less than or equal to 10[Formula: see text]min.

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