A Displacement Bound Principle for Inelastic Continua Subjected to Certain Classes of Dynamic Loading

1965 ◽  
Vol 32 (1) ◽  
pp. 1-6 ◽  
Author(s):  
J. B. Martin

The paper presents an inequality relating statically admissible stress fields and kinematically admissible displacement fields for continua composed of inelastic materials which obey a postulated criterion of stability. The inequality is used to compute displacement bounds for inelastic continua subjected to certain classes of dynamic loading.

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4023
Author(s):  
Leonardo M. Honório ◽  
Milena F. Pinto ◽  
Maicon J. Hillesheim ◽  
Francisco C. de Araújo ◽  
Alexandre B. Santos ◽  
...  

This research employs displacement fields photogrammetrically captured on the surface of a solid or structure to estimate real-time stress distributions it undergoes during a given loading period. The displacement fields are determined based on a series of images taken from the solid surface while it experiences deformation. Image displacements are used to estimate the deformations in the plane of the beam surface, and Poisson’s Method is subsequently applied to reconstruct these surfaces, at a given time, by extracting triangular meshes from the corresponding points clouds. With the aid of the measured displacement fields, the Boundary Element Method (BEM) is considered to evaluate stress values throughout the solid. Herein, the unknown boundary forces must be additionally calculated. As the photogrammetrically reconstructed deformed surfaces may be defined by several million points, the boundary displacement values of boundary-element models having a convenient number of nodes are determined based on an optimized displacement surface that best fits the real measured data. The results showed the effectiveness and potential application of the proposed methodology in several tasks to determine real-time stress distributions in structures.


2010 ◽  
Vol 97-101 ◽  
pp. 1223-1226
Author(s):  
Jun Lin Li ◽  
Shao Qin Zhang

The problem of orthotropic composite materials semi-infinite interfacial crack was studied, by constructing new stress functions and employing the method of composite material complex. In the case that the secular equations’ discriminates the and theoretical solutions to the stress fields and the displacement fields near semi-infinite interface crack tip without oscillation and inter-embedding between the interfaces of the crack are obtained, a comparison with finite element example was done to verify the correction of theoretical solution.


2017 ◽  
Vol 62 (4) ◽  
pp. 2081-2087 ◽  
Author(s):  
T. Pała ◽  
I. Dzioba

Abstract The paper presents the results of two butt welded joints by conventional method. The welding process was performed using a variety of linear welding energy. The studies included experimental and computational part. In experimental studies determined the distribution of hardness and mechanical properties of the individual analyzed sections of welded joints. The data obtained were intended to determine the extent of zones in the welded joints that have certain strength characteristics. Also conducted uniaxial tensile tests of welded joints with the registration of displacement fields on the surface of specimens by means of Aramis video-system what the final result are images of strain fields map on the surface of welded joints. The resulting strain values were compared with the results of numerical computations FEM.


2011 ◽  
Vol 413 ◽  
pp. 223-228
Author(s):  
Xue Cheng Ping ◽  
Xing Li ◽  
Xiao Xiang Xu

Failure in anisotropic/isotropic bi-materials starts at the interface, and the interfacial failure is of interest to some engineering fields such as automobile and aviation industry. Many researchers have done a lot of research on this field, but many did not consider a specific stress component near the interface corner tip as a parameter of a failure criterion. Kun Cheol Shin, introducted a failure criterion for anisotropic/isotropic bi-materials problem with a wedge. But the process of obtaining the singular stress fields of anisotropic/isotropic bi-materials is complex. To solve this problem, we have taken a new method which is from Xuecheng-Ping and M.-C. Chen.The method is new, which is based on displacement and more easily in calculating the stress and displacement fields surrounding a wedge tip than before. Through this method, we establish a criterion base on the-plan. The failure criterion can be used not only to predict stress intensities of co-cured double lap joints that with thermal and mechanical load, but also to predict stress intensities of co-cured double lap joints that with different materials or lap length. And we describe the process of calculating singular stress fields and stress intensities of co-cured double lap joints with a wedge that consists of glass fiber reinforced composites and steel adherends.


1991 ◽  
Vol 58 (4) ◽  
pp. 982-987 ◽  
Author(s):  
A. Piva ◽  
E. Radi

The dynamic stress and displacement fields in the neighborhood of the tip of a crack propagating in an orthotropic medium are obtained. The approach deals with the methods of linear algebra to transform the equations of motion into a first-order elliptic system whose solution is sought under the assumption that the local displacement field may be represented under a scheme of separated variables. The analytical approach has enabled the distinction between two kinds of orthotropic materials for which explicit espressions of the near-tip stress fields are obtained. Some results are presented graphically also in order to compare them with the numerical solution given in a quoted reference.


1987 ◽  
Vol 9 (2) ◽  
pp. 24-28
Author(s):  
Vu Van The ◽  
Tran Ba Tinh

A new displacement bound technique, which is based on concept of admissible fields has been developed for rigid Plastic continua subjected to strong dynamic loading at large deflections, the lower hound obtained (2.11) depends on kinematic ally admissible displacement  ui and kinematic ally admissible velocity ui* which must be chosen so that the condition (2.14) may be satiafidc. Parameter T* would be determinated by maximizing the right hand side of (2.11).


2002 ◽  
Vol 7 (3) ◽  
pp. 151-155 ◽  
Author(s):  
Yu Guangming ◽  
Zhao Jianfeng ◽  
Xie Heping

Mining-caused activation of fault is an important research subject in mining science. In the past, the influences of geometrical morphology of fault surface on the activation have not been revealed. In view of the fractal character of fault surface, the self-affine fractal curves and geological-mining models with these kinds of fractal fault surface are constructed in order to numerically simulate the mining-caused activation phenomenon of fractal fault surface, and the law of influence of fractal fault surface on mining subsidence is studied and summarized. Our study shows that the mining-cased activation of fault has remarkable fractal interface effect; the mechanical behavior of mining-caused shearing sliding of fault is correlated with its fractal dimension, and after mining-caused activation fault surface with different fractal dimensions will result in different stress fields and different displacement fields in the nearby rock mass.


2011 ◽  
Vol 233-235 ◽  
pp. 1950-1953
Author(s):  
Cai Xia Ren ◽  
Jun Lin Li

The orthotropic bi-material plane interface end of a flat lap is studied by constructing new stress functions and using the composite complex function method of material fracture. When the characteristic equations’ discriminates and, the theoretical formulas of stress fields, displacement fields and the stress intensity factor around the flat lap interface end are derived, indicating that there is no oscillatory singularity. There are multiple stress singularities of the orthotropic bi-material plane flat lap interface end.


2010 ◽  
Vol 44-47 ◽  
pp. 2827-2831
Author(s):  
Jun Lin Li ◽  
Cai Xia Ren ◽  
Wen Ting Zhao ◽  
Jing Zhao

The orthotropic bi-material plane interface end of a flat lap is studied by constructing new stress functions and using the composite complex function method of material fracture. When the characteristic equations’ discriminates and , the theoretical formulas of stress fields, displacement fields and the stress intensity factor around the flat lap interface end are derived, indicating that there is no oscillatory singularity. There are multiple stress singularities of the orthotropic bi-material plane flat lap interface end.


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