Key Engineering Materials Vols. 488-489

Abstract: Residual stress and strain states, produced during cold drawing, play a key role in hydrogen embrittlement (HE) of prestressing steel wires, because of hydrogen accumulation in certain places of the material is affected by stress and strains fields. Taking into account that the drawing straining path directly affects both residual stress and plastic strain distribution, the aim of the present paper is to clarify the influence of drawing straining path in the residual state and, consequently, its influence on the HE process of prestressing steel wires.

Abstract: A recent trend in the development of CO2 pipelines is the shift from the predominance of transport of CO2 for enhanced oil recovery (EOR) to the transportation of CO2 as part of the carbon capture and storage (CSS) process for global warming mitigation. Among the processes of capture, transport, and storage, less attention has been paid to transport as it is assumed to be for granted, existing technology. This paper presents a focused analysis of the problem of structural integrity of CO2 pipelines through reviewing the state-of-the-art literature and practice, and highlights the need for a unified code of practice for the modelling of integrity and, due to the potentially hazardous nature of CO2, safety, in these pipelines.

Abstract: In this work, multiaxial fatigue tests results on [0_F/90_U,3/0_F] glass/epoxy tubes are discussed. Specimens are subjected to combined tension-torsion loadings, resulting in the stress components σ₂ and τ₁₂ in the 90° layers of the tubes. The effect of shear stress on damage mechanics has been investigated and a strong influence on both damage onset and propagation has been observed. SEM investigation of fracture surfaces shows the dependence of damage modes, at the microscopic scale, on the multiaxiality condition. Comparison with previous results on tubes with different lay-ups ([90₄], [0_F/90_U,3]) shows the strong influence of the constraining 0° fabric layers on the damage onset and propagation.

Abstract: In diagnostics, noise can be a very reliable way of defining the condition of mechanical systems. There are different methods to visualise the noise source. Primarily, they deal with a specific noise source in a specific acoustic environment. This paper presents a visualization method of complex noise sources, using an acoustic camera. This method makes it possible to visualise all types of different complex noise sources; a special acoustic algorithm is applied for this purpose. Also, it is possible to observe various transient acoustical phenomena.

Abstract: In this paper, the exact forms of integrals in the meshless local boundary integral equation method are presented and applications were demonstrated for fracture mechanics. A weak form for a set of governing equations with a unit test function or polynomial test functions is transformed into local integral equations. Each node has its own support domain and is surrounded by a local integral domain with different shapes of boundaries. The meshless approximation based on the Radial Basis Function (RBF) is employed for the implementation of displacements. For cracked plate, opening displacement on the crack surface can be obtained with satisfactory accuracy without special treatment for stresses singularities at crack tip.

Abstract: Following the first experimental results concerning the possibility to estimate the fatigue limit by semi-static tensile traction test, the authors are continuing the experimental thermo-analysis of the curve zone between the origin and the yield stress; that is rich of indication about the fatigue failure process. The tests carried out on the AISI 304 steel by thermal analysis, confirmed the good approximation between the values of the fatigue limit estimated by fatigue test and by the quasi-static test. The results shoed the importance of the thermo-analysis of the part of the stress-strain curve (distant from the yield point) where only in macroscopic terms the behavior is perfectly elastic.

Abstract: The residual stress was measured through the proposed method with ESPI measurement system. The proposed measurement method as a basic study combined with theory and experiments applied for residual stresses prediction and developments of safety estimation technique.