This paper presents new methodology for determining the actual stress–strain diagram based on analytical equations, in combination with numerical and experimental data. The first step was to use the 3D digital image correlation (DIC) to estimate true stress–strain diagram by replacing common analytical expression for contraction with measured values. Next step was to estimate the stress concentration by using a new methodology, based on recently introduced analytical expressions and numerical verification by the finite element method (FEM), to obtain actual stress–strain diagrams, as named in this paper. The essence of new methodology is to introduce stress concentration factor into the procedure of actual stress evaluation. New methodology is then applied to determine actual stress–strain diagrams for two undermatched welded joints with different rectangular cross-section and groove shapes, made of martensitic steels X10 CrMoVNb 9-1 and Armox 500T. Results indicated that new methodology is a general one, since it is not dependent on welded joint material and geometry.

An attention in this paper is focused on the stress analysis and the determination of fracture mechanics parameters in low pressure (LP) turbine rotor discs and on developing analytic expressions for stress intensity factors at the critical location of LP steam turbine disc. Critical locations such as keyway and dovetail area experienced stress concentration leading to crack initiation. Major concerns for the power industry are determining the critical locations with one side and fracture mechanics parameters with the other side. For determination of the critical locations in LP turbine rotor disc conventional finite elements are used here. For this initial crack length and during crack growth it is necessary to determine SIFs. In fatigue crack growth process it is necessary to have analytic formulas for the stress intensity factor. To determine analytic formula for stress intensity factor (SIF) of cracked turbine rotor disc special singular finite elements are used. Using discrete values of SIFs which correspond to various crack lengths analytic formula of SIF in polynomial forms is derived here. For determination of SIF in this paper, combined J‐integral approach and singular finite elements are used. The interaction of mechanical and thermal effects was correlated in terms of the fracture toughness.

The introduction of resin-based cements and an adhesive-bonding system in daily dental practice has given the opportunity to increase the retention of previously conventional cemented restorations and the optimal results in esthetic. This experimental study employed the 3D Digital Image Correlation Method (3D-DIC) for detecting shrinkage strain in four dual cured composite cements. The aim was to visualize measure, analyze, and compare strain fields in four resin-based cements using the 3D-DIC method. A total of 72 samples were divided into 4 groups considering variations in sample types, diameter, and thickness. Four types of composite cements: RelyX U200 (3 M ESPE, St. Paul, MN, USA), MaxCem Elite (Kerr, Orange, CA, USA), Multilink Automix (Ivoclar Vivadent, Schaan, Liechtenstein), and SeT PP (SDI, Australia) were used. Each type had diameters of 3 mm, 4 mm, and 5 mm, respectively, combined with two different values of thickness: 1 mm and 2 mm. Thickness had an important role on strain detected in all tested materials showing higher strain in samples with 2 mm thickness compared to 1 mm samples. Shrinkage strain values were the highest in Set PP samples indicated the possibility of undesirable de-bonding.

The service life of thick-walled power plant components exposed to creep, as is the case with pipelines of fresh- and re-heated steam, depend on the exhaustion rate of the material. Plant operation at elevated temperatures and at temperatures below designed temperatures all relates to the material exhaustion rate, thus complicating remaining life assessment, whereas the operating temperature variation is a most common cause in the mismatching of real service- and design life. Apart from temperature, the tube wall stress is a significant variable for remaining life assessment, whose calculation depends on the selected procedure, due to the complex pipeline configuration. In this paper, a remaining life assessment is performed according to the Larson-Miller parametric relation for a ?324?36 pipe bend element of a fresh steam-pipeline, made of steel class 1Cr0.3Mo0.25V, after 160 000 hours of operation. The temperature history of the pipeline, altogether with the pipe bend, is determined based on continuous temperature monitoring records. Compared results of remaining life assessment are displayed for monitored temperature records and for designed operating temperature in the same time period. The stress calculation in the pipe bend wall is performed by three methods that are usually applied so to emphasize the differences in the obtained results of remaining life assessment.

Corrosion effects on structural integrity and life of oil rig welded pipes are analysed by experimental, analytical, and numerical methods. Experiments were performed using standard tensile specimens and CT specimens for static loading, Charpy specimens for impact loading, and 3 Point Bending specimens for fatigue crack growth with amplitude loading. In each case new and old pipes were used to evaluate corrosion effects. Results indicated negligible corrosion effects in the case of tensile properties and impact toughness, and strong effects in the case of fracture toughness and especially fatigue crack growth rates, increasing the risk of static failure and reducing significantly structural life. Analytical expressions are used for oil rig pipe structural integrity and life assessment to quantify these effects. Recently introduced risk-based approach is applied to analyse oil rig drill pipe with a corrosion defect treated as a surface crack.

In the present study, andesite basalt originated from the deposit site ?Donje Jarinje?, Serbia, was examined as a potential raw material for high-density ceramics production. The production of high-density ceramics included dry milling, homogenization, cold isostatic pressing and sintering in the air. To determine the optimal processing parameters the sintering was conducted at 1040, 1050, 1060, 1070 and 1080?C, and afterwards the sintering duration was varied from 30 to 240min at the optimal sintering temperature of 1060?C. Characterization of the starting and sintered materials included the estimation of particle size distribution, density, hardness and fracture toughness complemented with X-ray diffraction, optical light microscopy, scanning electron microscopy and energy dispersive spectroscopy analysis. Phase transformations did not occur during processing in the investigated temperature range from 1040 to 1080?C. The obtained research results showed that 99.5% of relative density and the highest hardness and fracture toughness values of 6.7GPa and 2.2MPa?m1/2, respectively, were achieved for the andesite basalt sintered at 1060?C for 60min in the air. The results of the present study confirmed that the sintered andesite basalt can be used as a high-density ceramic material for various industrial applications.