Experimental investigations of elastic-plastic strain states on various stages of material plastifying

Abstract

In the paper, the possibility of application of various experimental methods to the analysis of elastic-plastic states at different levels of material plastifying is presented. For tests carried out on two-dimensional elements with different stress concentrators and loaded by tensile stresses, three experimental methods have been selected: Moiré method, method of photoelastic coating and the thermography method. On the basis of the tests results, the range of the applicability of chosen methods and their suitability to the elastic-plastic strain analysis at the development of material plastifying has been determined. The strain components distribution obtained from the Moiré method and the method of photoelastic coating has been compared. The possibility of increasing the accuracy of strain determination for the Moiré method by additional tests at the grid rotated by an angle of 45• with respect to the direction of tensile stress has been shown. The results of the investigations have been discussed.

Asymptotic Solutions for Multi-Hole Problems: Plane Strain versus Plane Stress Boundary Conditions in Borehole Applications

“…However, the disparities between the model results and actual displacements in the natural prototype can rarely be evaluated in detail, but some theoretical extrapolations are still possible (see ref. [10] for some experimental methods).…”

“…( 5) and ( 6), can be obtained directly from the plane stress solution, Eqs. ( 9) and (10), by replacing E with E= 1 À v 2 ðÞ , and v with v= 1 À v ðÞ as follows:…”

“…Plane strain solutions are developed in the present study to quantify the delta between the solutions due to the assumed boundary condition. Additionally, the LSM multihole results are validated against-(1) photo-elastic contour patterns for a 5-hole problem of Koslowska [10], and (2) a numerical example of Yi et al [11]. The present study is limited to hole analysis based on a linear elasticity assumption for isotropic elastic plates; borehole analysis of anisotropic media was given in prior work [4,9], applying equations developed for plane stress cases in [12].…”

“…The 5-hole photo-elastic prototype. (a) Plate dimensions, (b) isochromatic pattern for strain state, (c) u x, y ðÞ displacement magnitude contours, (d) v x, yðÞ displacement magnitude contours (after[10]).…”

Archive of Mechanical Engineering

“…This method makes use of the relations between the strain and stress tensor components (Hooke's law), and its extension for the overelastic range of the material requires creating analogous relations for nonlinear part of the characteristic. For derivation of formulas describing the mentioned relations, the geometrical model of real σ − ε curve was considered [3], [4]. In this model, the experimentally obtained material characteristic is replaced by n line segments (Fig.…”