Material response to shock/dynamic loading: Windows into kinetic and stress-state effects on defect generation and damage evolution

2012 ◽  
Author(s):  
George Thompson Gray III
Keyword(s):  
Stress State ◽  
Dynamic Loading ◽  
Damage Evolution ◽  
Material Response ◽  
Defect Generation

scholarly journals Analysis of Damage Evolution of Sandstone under Uniaxial Loading and Unloading Conditions Based on Resistivity Characteristics

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Guoyin Wu ◽  
Kui Wang ◽  
Mingjie Zhao ◽  
Zhichao Nie ◽  
Zhen Huang
Keyword(s):  
Stress State ◽  
Damage Evolution ◽  
Damage Model ◽  
Damage Variable ◽  
Uniaxial Loading ◽  
Experimental Comparison ◽  
Variable Expression ◽  
Cyclic Loading And Unloading ◽  
Sandstone Rock ◽  
Loading And Unloading

In complex rock engineering, understanding the stress state and determining stability and damage evolution are necessary. To more accurately provide a theoretical basis for judging the stress state of bedrock in engineering, this study experimentally addressed the damage evolution of sandstone under loading and unloading conditions. A theoretical relationship between rock resistivity and porosity was obtained according to the Archie formula, which allowed the derivation of the sandstone damage variable expression. Then, sandstone rock samples were used for experimental evaluation, and the feasibility of the theoretically determined damage variable was verified. Finally, through theoretical and experimental comparison analysis, we developed a correlative damage model for sandstone under uniaxial loading and unloading. The results show that the damage variable varies linearly with strain. The proposed correlative equation describes this behavior accurately for loading and unloading conditions. Based on the results of this study, the correlative damage model of sandstone under cyclic loading and unloading conditions can be further improved to be a complete constitutive damage model.

Assessment of Stress-Displacement State of Cable Suspended Pipeline Bridge During Inspection Pig Motion

2016 ◽  
Author(s):  
Igor Orynyak ◽  
Igor Burak ◽  
Sergiy Okhrimchuk ◽  
Andrii Novikov ◽  
Andrii Pashchenko
Keyword(s):  
Stress State ◽  
Dynamic Loading ◽  
System Analysis ◽  
Optical Measurement ◽  
Time Moment ◽  
Dynamic Loads ◽  
Natural Mode ◽  
Geometrically Nonlinear ◽  
Cable System ◽  
Stress Calculation

Designing and maintenance of pipeline cable bridge with dynamic loads is complex because this problem belongs to the geometrically nonlinear problems. Analysis shown that existing mathematics models of cables have restrictions in use and we can’t use these cable models for dynamic loads calculations of cable-suspended pipeline bridge. Movement, produced by motion of inspection pig inside pipeline is an example of such dynamic loads. During its motion through the pipeline cable bridge the inspection pig induces additional stresses in pipeline due its weight and finite velocity which induces the vibration of the bridge. Its stress state assessment requires a lot of modeling, measuring and calculating actions to be done. First of all the initial static stress state of the cable bridge should be evaluated. It depends on the existing tension forces in the cable elements. They approximately were derived from the optical measurement of their geometrical curvatures with accounting for known weight density of the cables. Then, existing software tool for piping stress calculation “3D Pipe Master”, which operates by 12 degrees of freedom in pipe elements, was modernized to be able to take into account the geometrically nonlinear behavior of 6 d.o.f. cable elements. The equations which relate the elongations and rotations of cable elements with tension forces in cables are written in the form convenient for application of the transfer matrix method in the linearized iteration procedure which adjusts the measured displacements of the elements of the bridge with calculated one. In this way the initial tension forces in cables, in particular, and the bridge state, in general were determined. The dynamic part of the problem is solved by expansion in terms of natural frequencies eigenfunctions. Given inspection pig velocity calculation allows to determine the time dependence of generalized loads for each of natural vibration mode as product of the pig weight multiplied by mode shape displacement in point of pig position at the given time moment. Eventually the technique of Duhamel integral is used to calculate the dynamic behavior of the bridge for each natural mode of vibration. Two examples of dynamic stress calculation are considered. First is primitive one and relate to calculation joint interaction pipeline and cable system at dynamic loading. The second example concerns dynamic calculation pipeline cable bridge through the river Svicha during movement inspection pig. This bridge consists of two support, two parallel pipelines (1220×15) with bends and cable system. Analysis shown possibility uses “3D Pipe Master” software for the solving problems of durability pipeline cable bridge any complexity in the conditions of static and dynamic loading.

Optimal aspect ratio of interference fits for maximum load transfer capacity

2005 ◽  
Vol 40 (2) ◽  
pp. 177-184 ◽  
Author(s):  
D Castagnetti ◽  
E Dragoni
Keyword(s):  
Stress State ◽  
Aspect Ratio ◽  
Load Transfer ◽  
Load Capacity ◽  
Frictional Coefficient ◽  
Axial Loading ◽  
Maximum Load ◽  
Material Response ◽  
Optimal Ratio ◽  
Joint Design

The stress state in frictional interference fits under torsional and axial loading is examined. The optimal ratio between the inside and outside diameters of the hub is calculated, which maximizes the load transmitted by the joint. Design formulae and charts are provided, giving the most efficient aspect ratio of the hub for all practical situations. It is found that the maximum load capacity is achieved for an aspect ratio in the range from 0.5 to 0.7, regardless of the frictional coefficient (up to 1), of the kind of loading (torsional or axial), and of the material response (brittle or ductile).

Damage evolution under cyclic multiaxial stress state: A comparative analysis between glass/epoxy laminates and tubes

2014 ◽  
Vol 61 ◽  
pp. 282-290 ◽  
Author(s):  
M. Quaresimin ◽  
P.A. Carraro ◽  
L.P. Mikkelsen ◽  
N. Lucato ◽  
L. Vivian ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Stress State ◽  
Damage Evolution ◽  
Multiaxial Stress ◽  
Multiaxial Stress State

scholarly journals Research of Transitional Failure Mode as Damage Evolution in Rock Wall

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiao-guang Li ◽  
Changhong Li ◽  
Yuan Li ◽  
Pu-jin Zhang
Keyword(s):  
Rock Mass ◽  
Stress State ◽  
Failure Mode ◽  
Damage Evolution ◽  
Failure Modes ◽  
Surface Instability ◽  
Biaxial Stress ◽  
Strength Analysis ◽  
Loading Test ◽  
Rock Wall

The stress condition of tunnel surrounding rock mass is complex. The stress concentration of in situ brittle rock mass caused by excavation results in localized damage evolution parallel to the free face, which is called surface instability. The rock wall shows the transition characteristics of the failure mode with the distance from the surface to the depth. Low strength surface instability and transition failure modes of the tunnel’s rock wall are common in deep condition but cylindrical specimens cannot simulate stress state of rock wall surface well in conventional rock mechanics tests. This paper conducted the indoor experimental study of the biaxial stress state and studied the surface instability of samples. An indoor test device for the simulation of transitional surface failure of the rock wall was developed. Through a biaxial stress loading test on the rectangular rock sample, the damage process and crack development of rock samples were analyzed, and the law of stress and strain related to the failure mode transition was characterized as well. Based on test results and strength analysis, an explanation of the failure theory and its corresponding model are proposed based on the maximum strain strength theory. Furthermore, this paper concludes that the failure mode of surface instability presents transition feature from brittle to ductile with the increase of distance from the surface to depth.

A Multiaxial Damage Statistic Constitutive Model for Concrete

2012 ◽  
Vol 166-169 ◽  
pp. 56-59
Author(s):  
Shan Suo Zheng ◽  
Wen Yong Li ◽  
Qing Lin Tao ◽  
Yu Fan
Keyword(s):  
Numerical Simulation ◽  
Quantitative Analysis ◽  
Stress State ◽  
Constitutive Equation ◽  
Evolution Equation ◽  
Damage Evolution ◽  
Equivalent Strain ◽  
Triaxial Stress State ◽  
Decoupling Method ◽  
Damage Evolution Equation

In order to apply the uniaxial damage evolution equation that established with the variable of strain to the multiaxial damage quantitative analysis, this paper bases on the Hsieh-Tang-Chen four-parameter failure criterion and adopts the way of making the triaxial equivalent strain combining with the uniaxial damage evolution equation to analyze and deduce the uniaxial damage evolution equation of SRHSHPC, and which is expanded to multiaxial condition as well. A function considered triaxial stress state and a related correction value are suggested, then, improving the damage evolution equation from triaxial to multiaxial form, finally proposing the multiaxial damage statistic constitutive equation for concrete, taking numerical simulation with the complete decoupling method and the result shows that the model is effective.

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