The problem of interaction of rod centralizers of casing with a well wall is considered. The paper aims at studying the ways of fastening of centralizer’s ends on the parameters of its rigidity and strength. Knowledge of these characteristics is necessary for the assessment of casing column drift and well completion quality. For simulation of the working links of the centralizers, the classical linear theory of smooth rods, rigid along the axis and elastic on bending is used. Stress-strain state of bow-type rod with six different variants of fastening under conditions of point contact is studied. The analytical relations between the contact force and the mutual approach of the column and the well wall, as well as the expressions for the admissible contact loads, are established. The way of fastening the rod significantly influences these characteristics; in particular, the fact of the presence or absence of freedom of mutual movement of its ends along the pipe is decisive. The engineering formulas, which serve as two-side estimations of the rigidity and strength of the real structures of centering devices, are obtained. A comparative analysis of mechanical properties of centralizers has been conducted.

This paper presents the effect of vibratory dissimilar TIG (Tungsten Inert Gas) welding process on hardness of welded joins with respect to change of vibratory parameters. In this study, new vibratory setup with two metal engravers is used to give mechanical vibrations to the specimens to be welded. Finally, the effect of mechanical vibrations with the variation of vibration parameters is studied on the hardness at the weld bead and heat effected zone (HAZ) of welded joints.

The article discusses the strength of concrete and other brittle materials in the case of non-uniform biaxial type of compression (σ1 > σ2 > 0) and triaxial compression of σ1 > σ2 = σ3 > 0 type (it was assumed that σ> 0 corresponds to compression). It is noted that, when considering the biaxial loading in the accepted model, probabilistic nature of distribution of stresses along the contour of pores and inclusions, i.e. stress causing formation and propagation of cracks in the material, plays an important role. Moreover, the stress across the circuit pores was regarded as a three-dimensional random field of S(α,β,γ,ω),where ω - is a random argument. Considering the average number of overshoots NR we believed that the random field of S is not homogeneous (not stationary): its expectation is not constant, but is a function of nonrandom arguments Мs = Мs(α;β;γ). External load, corresponding to NR = const (and at the same time constant of level exceedance probability), first increases and then decreases a little. Heating up to 300оС (573K) and 400оС (673K) leads to violations, and long-term load leads to significant changes in the macro- and microstructure of concrete.

This paper presents a methodology to improve the strength or the Modulus of Rupture (MOR) of fibre cement. The Six Sigma approach with the DMAIC steps was applied to a case study company. This research started from defining problem, setting the project objective and the project scope. Next, the measurement system was analyzed and the process map was set up. The potential factors of the problem was then determined. Due to there were many factors that affect the MOR, the Cause and Effect Matrix and the Failure Mode and Effect Analysis technique were then used to reduce the number of factors to be studied further. Next, three process factors, which were the pulp slurry freeness, the film-layer thickness, and the pressure step, were optimized using the results from the Box-Behnken experimental design. Other 13 remaining factors were improved by creating or revising the standard work instructions and training the operators. After that, the statistical process control and the control plan were set up to control the production processes. After improvement, the process capability index (Ppk) significantly increased from 0.26 to 1.35.