Reactivation tendency analysis: A theory for predicting the temporal evolution of preexisting weakness under uniform stress state

2011 ◽  
Vol 503 (3-4) ◽  
pp. 195-200 ◽  
Author(s):  
Hengmao Tong ◽  
An Yin
Keyword(s):  
Stress State ◽  
Temporal Evolution ◽  
Uniform Stress ◽  
Uniform Stress State ◽  
Tendency Analysis

Uniform Stress State in Bone Structure With Residual Stress

1998 ◽  
Vol 120 (3) ◽  
pp. 342-347 ◽  
Author(s):  
T. Adachi ◽  
M. Tanaka ◽  
Y. Tomita
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cancellous Bone ◽  
Bone Structure ◽  
Circumferential Direction ◽  
Uniform Stress ◽  
Model Study ◽  
Uniform Stress State ◽  
Cancellous Bone Structure ◽  
Living Tissues

Residual stress and strain in living tissues have been investigated from the viewpoint of mechanical optimality maintained by adaptive remodeling. In this study, the residual stresses in the cortical-cancellous bone complex of bovine coccygeal vertebrae were examined. Biaxial strain gages were bonded onto the cortical surface, so that the gage axes were aligned in the cephalocaudal and circumferential directions. Strains induced by removal of the end-plate and the cancellous bone were recorded sequentially. The results revealed the existence of compressive residual stress in the cortical bone and tensile residual stress in the cancellous bone in both the cephalocaudal and the circumferential direction. The observed strains were examined on the basis of the uniform stress hypothesis using a three-bar model for the cephalocaudal direction and a three-layered cylinder model for the circumferential direction. In this model study, the magnitude of effective stresses, which is defined as the macroscopic stress divided by the area fraction of bone material, was found not to differ significantly between cephalocaudal and circumferential directions, although they were evaluated using independent models. These results demonstrate that the uniform stress state of the cortical-cancellous bone structure is consistent with results obtained in the cutting experiment when the existence of residual stress is taken into account.

Implementation of Incremental Yield Condition for Continual Problems with Singularity

2019 ◽  
Vol 974 ◽  
pp. 620-626 ◽  
Author(s):  
Sergey Y. Kalashnikov ◽  
Elena Gurova ◽  
Renat Kuramshin ◽  
Vladimir Kharlanov
Keyword(s):  
Stress State ◽  
Plastic Material ◽  
Limit State ◽  
Yield Condition ◽  
Initial Moment ◽  
Elastic State ◽  
Uniform Stress ◽  
Uniform Stress State ◽  
Analytical Expressions ◽  
State Criterion

The limit elastic state of an infinitely large half-plane under the action of concentrated vertical and horizontal forces has been considered. The gradient yield condition specifying the elasto-plastic material yielding initial moment at non-uniform stress state is used as the limit state criterion. The analytical expressions allowing to interpret the result in the singular point have been derived.

scholarly journals Effect of inherent microcrack populations on rock tensile fracture behaviour: numerical study based on embedded discontinuity finite elements

2021 ◽  
Author(s):  
Timo Saksala
Keyword(s):  
Stress State ◽  
Finite Elements ◽  
Numerical Simulations ◽  
Uniaxial Tension ◽  
Fracture Behaviour ◽  
Tensile Fracture ◽  
Uniform Stress ◽  
Three Point Bending ◽  
Rock Heterogeneity ◽  
Uniform Stress State

AbstractInherent microcrack populations have a significant effect on the fracture behaviour of natural rocks. The present study addresses this topic in numerical simulations of uniaxial tension and three-point bending tests. For this end, a rock fracture model based on multiple intersecting embedded discontinuity finite elements is developed. The inherent (pre-existing) microcrack populations are represented by pre-embedded randomly oriented discontinuity populations. Crack shielding (through spurious locking) is prevented by allowing a new crack to be introduced, upon violation of the Rankine criterion, in an element with an initial crack unfavourably oriented to the loading direction. Rock heterogeneity is accounted for by random clusters of triangular finite elements representing different minerals of granitic numerical rock. Numerical simulations demonstrate the strength lowering effect of initial microcrack populations. This effect is substantially stronger under uniaxial tension, due to the uniform stress state, than in semicircular three-point bending having a non-uniform stress state with a clear local maximum of tensile stress.

Simplified Prediction of Ply Steer in Radial Tires

1980 ◽  
Vol 8 (1) ◽  
pp. 3-9 ◽  
Author(s):  
C. W. Bert
Keyword(s):  
Composite Laminate ◽  
Ground Plane ◽  
Lateral Force ◽  
Rolling Contact ◽  
Slip Angle ◽  
Uniform Stress ◽  
Rubber Composite ◽  
Laminate Theory ◽  
Contact Models ◽  
Uniform Stress State

Abstract Ply steer is a rolling contact phenomenon which manifests itself as a lateral force acting at the ground plane of a tire constrained in yaw or a change in slip angle of a tire free to yaw. It has long been known that radial tires generally exhibit greater ply steer than do bias tires. However, the only previously published quantitative analysis of this phenomenon considered the multi-layer cord-rubber composite by means of netting analysis, which is not very accurate at cord angles typical of radial tire belts. A simple, explicit expression is developed herein by combining modern composite laminate theory with two very simple, uniform-stress-state tire-road contact models. The ply-steer results predicted by the resulting expressions are compared with some experimental results and the agreement is found to be reasonably satisfactory.

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