Statistical variability in the strength and failure strain of aramid and polyester yarns

1994 ◽  
Vol 29 (19) ◽  
pp. 5141-5152 ◽  
Author(s):  
G. Amaniampong ◽  
C. J. Burgoyne
Keyword(s):  
Failure Strain ◽  
Statistical Variability

Failure Strain and Fracture Prediction During Shock Tube Impact Forming of AA 5052-H32 Sheet

2021 ◽  
pp. 1-39
Author(s):  
Saibal Kanchan Barik ◽  
Ganesh R Narayanan ◽  
Niranjan Sahoo
Keyword(s):  
Finite Element ◽  
Flow Stress ◽  
Shock Tube ◽  
Failure Strain ◽  
Experimental Situation ◽  
Rate Sensitivity ◽  
Fracture Pattern ◽  
Failure Model ◽  
Stress Models ◽  
Cook Model

Abstract The present study deals with both numerical and experimental evaluation of failure strain and fracture pattern during shock tube impact forming of 1.5 mm thick AA 5052-H32 sheet. A hemispherical end nylon striker is propelled to deform the sheet at different velocities. Here the main objective is to understand the effect of flow stress models and fracture models on the forming outputs. The experimental situation is modelled in two stages, i.e., incorporating the pressure in the first stage, and displacement of the striker in the second stage in finite element simulation using the finite element (FE) code (DEFORM-3D). A new strategy followed to evaluate the rate-dependent flow stress data from the tensile test of samples sectioned from shock tube-based deformed sheet is acceptable, and finite element simulations incorporating those properties predicted accurate failure strain and fracture pattern. Out of all the flow stress models, the modified Johnson-Cook model has a better flow stress predictability due to the inclusion of the non-linear strain rate sensitivity term in the model. During the prediction of the failure strain and necking location, Cockcroft-Latham failure model, Brozzo failure model, and Freudenthal failure model have a fair agreement with experimental data in combination with the two flow stress models, i.e., Johnson-Cook model and modified Johnson-Cook model.

scholarly journals Rib Cortical Bone Fracture Risk as a Function of Age and Rib Strain: Updated Injury Prediction Using Finite Element Human Body Models

2021 ◽  
Vol 9 ◽  
Author(s):  
Karl-Johan Larsson ◽  
Amanda Blennow ◽  
Johan Iraeus ◽  
Bengt Pipkorn ◽  
Nils Lubbe
Keyword(s):  
Finite Element ◽  
Fracture Risk ◽  
Cortical Bone ◽  
Failure Strain ◽  
Risk Function ◽  
Rib Fracture ◽  
Probabilistic Framework ◽  
Age Dependent ◽  
Risk Curve ◽  
Human Body Models

To evaluate vehicle occupant injury risk, finite element human body models (HBMs) can be used in vehicle crash simulations. HBMs can predict tissue loading levels, and the risk for fracture can be estimated based on a tissue-based risk curve. A probabilistic framework utilizing an age-adjusted rib strain-based risk function was proposed in 2012. However, the risk function was based on tests from only twelve human subjects. Further, the age adjustment was based on previous literature postulating a 5.1% decrease in failure strain for femur bone material per decade of aging. The primary aim of this study was to develop a new strain-based rib fracture risk function using material test data spanning a wide range of ages. A second aim was to update the probabilistic framework with the new risk function and compare the probabilistic risk predictions from HBM simulations to both previous HBM probabilistic risk predictions and to approximate real-world rib fracture outcomes. Tensile test data of human rib cortical bone from 58 individuals spanning 17–99 years of ages was used. Survival analysis with accelerated failure time was used to model the failure strain and age-dependent decrease for the tissue-based risk function. Stochastic HBM simulations with varied impact conditions and restraint system settings were performed and probabilistic rib fracture risks were calculated. In the resulting fracture risk function, sex was not a significant covariate—but a stronger age-dependent decrease than previously assumed for human rib cortical bone was evident, corresponding to a 12% decrease in failure strain per decade of aging. The main effect of this difference is a lowered risk prediction for younger individuals than that predicted in previous risk functions. For the stochastic analysis, the previous risk curve overestimated the approximate real-world rib fracture risk for 30-year-old occupants; the new risk function reduces the overestimation. Moreover, the new function can be used as a direct replacement of the previous one within the 2012 probabilistic framework.

scholarly journals Length Scale and Aging Effect on the Mechanical Properties of a 63Sn-37Pb Solder Alloy

2000 ◽  
Author(s):  
T. Jesse Lim ◽  
Wei-Yang Lu
Keyword(s):  
Ultimate Strength ◽  
Tensile Testing ◽  
Failure Strain ◽  
Aging Effect ◽  
Uniaxial Tensile ◽  
Strain Response ◽  
Stress Strain ◽  
Uniaxial Tensile Testing ◽  
Aging Conditions ◽  
Strain Responses

Abstract In this work, uniaxial tensile testing of a 63Sn-37Pb alloy with different specimen sizes and aging conditions had been carried out. Although the stress-strain responses of different specimen sizes and aging conditions differs, the ultimate strength of the specimens with 16 hours, 100°C aging are similar for the sizes tested. The specimens with 25 days, 100°C aging have different stress-strain response with different sizes, and have a lower ultimate strength and higher failure strain compared to 16 hours, 100°C aging specimens.

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