Application of DIC Method in the Analysis of Stress Concentration and Plastic Zone Development Problems

Abstract

The paper presents the assessment of the possibility and reliability of the digital image correlation (DIC) system for engineering and scientific purposes. The studies were performed with the use of samples made of the three different materials—mild S235JR + N steel, microalloyed fine‑grain S355MC steel, and high strength 41Cr4 steel subjected to different heat‑treatment. The DIC studies were focused on determinations of dangerous zones with large stress concentrations, plastic deformation growth, and prediction of the failure zone. Experimental tests were carried out for samples with different notches (circular, square, and triangular openings). With the use of the DIC system and microstructure analyses, the influence of different factors (laser cutting, heat treatment, material type, notch shape, and manufacturing quality) on the material behavior were studied. For all studied cases, the stress concentration factors (SCF) were estimated with the use of the analytical formulation and the finite element analysis. It was observed that the theoretical models for calculations of the influence of the typical notches may result in not proper values of SCFs. Finally, the selected results of the total strain distributions were compared with FEM results, and good agreement was observed. All these allow the authors to conclude that the application of DIC with a common digital camera can be effectively applied for the analysis of the evolution of plastic zones and the damage detection for mild high‑strength steels, as well as those normalized and quenched and tempered at higher temperatures.

Determination of Stress Concentration Effects Using Micro-Digital Image Correlation Techniques in PMMA Specimens

“…Cerbu et al have successfully used this technique to characterize the mechanical response of glass fiber composites [12], while Dudescu et al [13] have determined the thermal expansion coefficient of polypropylene and polyvinylchloride. Romanowicz et al [14] have shown the DIC capability of determining stress concentration factors on samples fabricated from ductile materials. They have proven the viability of the method by obtaining comparable results between DIC techniques and FEM analysis.…”

Using the Effect of Compression Stress in Fatigue Analysis of the Roller Bearing for Bimodal Stress Histories

“…Fatigue failures are caused by random, repetitive, or cyclic loads that are generally significantly lower than loadings that would lead to the plastic deformation of the material. The onset of fatigue cracks may occur due to material imperfections, structural discontinuities, or stress concentrators [ 3 , 4 , 5 , 6 , 7 , 8 ]. The applied fatigue loads may be uniaxial (with one stress component), biaxial (with two stress components), or multiaxial (with more than two stress components) [ 9 , 10 , 11 ].…”

Study on Micro-Structure and Tensile Mechanical Properties of Dissimilar Metal Weld Joint Connecting Steam Generator Nozzle and Safe-End

“…In recent years, the rapid development of computer technology has promoted the gradual maturity of 3D digital technology. The digital image correlation (DIC) technology used for measuring surface deformities has the characteristics of "non-contact" [12,13] and "full-field" [14][15][16] displacement information on the surface. It is the most promising 3D data acquisition method in current engineering applications and can be used to measure tensile mechanical properties of welding joints.…”