In the present paper, the theory of generalized photo-thermoelasticity under fractional order derivative was used to study the coupled of thermal, plasma, and elastic waves on unbounded semiconductor medium with a cylindrical hole during the photo-thermoelastic process. The bounding surface of the cavity was traction free and loaded thermally by exponentially decaying pulse boundary heat flux. The medium was considered to be a semiconductor medium homogeneous, and isotropic. In addition, the elastic and thermal properties were considered without neglecting the coupling between the waves due to thermal, plasma and elastic conditions. Laplace transform techniques were used to obtain the exact solution of the problem in the transformed domain by the eigenvalue approach and the inversion of Laplace transforms were carried out numerically. The results were displayed graphically to estimate the effect of the thermal relaxation time and the fractional order parameters on the plasma, thermal and elastic waves.

A review of some recent data from multiaxial fatigue data from different notched materials is carried out in the paper. The approach based on the strain energy density (SED) averaged over a control volume is first used to summarise uniaxial and multiaxial fatigue strength data of welded joints made of structural steel and aluminium alloys. In all welded joints, the weld toe and weld root regions are modelled like sharp, zero radius, V-notches with different opening angles. The control volume radius is 0.28 mm for structural steels, 0.12 mm for aluminium alloys. Afterwards the SED approach is applied to multi-axial fatigue data from plain and V-notched specimens made of AISI 416 stainless steel (hardened and tempered state), subjected to tension, torsion and combined tension and torsion, both in-phase and out-of-phase. Notched specimens are characterised by a very small root radius, ρ=0.1 mm, which results in high nonlinear effects ahead of the notch tips. All results are summarised in terms of Δ W-N (SED range versus cycles to failure) scatterbands. Together with the new results, a number of multi-axial fatigue data recently obtained from sharply notched specimens made of C40 steel (normalised state) and 39NiCrMo3 steel (hardened and tempered state) are represented with the aim to provide a global synthesis in terms of local SED. Finally a synthesis from Ti6Al4V alloy is carried out showing the capability of the SED approach to be applied also to light alloys.

The linear elastic analysis of homogeneous, isotropic cracked bodies started in the 1900s. The existence of three dimensional corner point effects in the vicinity of a corner point where a crack front intersects a free surface was investigated in the late 1970s. An approximate solution by Bažant and Estenssoro explained some features of corner point effects but there were various paradoxes and inconsistencies. Results derived from finite element models showed that the analysis is incomplete. The stress field in the vicinity of a corner point appears to be the sum of two different singularities (i.e. stress intensity factors and corner point singularities). In this paper some recent results for the corner point singularities under in and out of plane loadings is reviewed and discussed.

Two procedures to evaluate fracture resistance of notched components are proposed in this contribution: the Strain Energy Density (SED) over a control volume and the Cohesive Zone Model (CZM). With the aim to simplify the application of the two fracture criteria, the concept of the ‘equivalent local mode I’ is presented. The control volume of the SED criterion and the cohesive crack of the CZM, have been rotated along the notch edge and centered with respect to the point where the elastic principal stress is maximum. Numerical predictions are compared with experimental results from U and V shaped notches under three point bending with notch root radius ranging from 0.2 to 4.0 mm. In parallel the loading conditions vary, from pure mode I to a prevailing mode II. All specimens were made of PMMA and tested at -60°C. The good agreement between theory and experimental results adds further confidence to the proposed fracture criteria.

The present paper summarizes the results from uniaxial-tension stress-controlled fatigue tests performed at different temperatures up to 650°C on Cu-Be specimens. Two geometries are considered: hourglass shaped and plates weakened by a central hole (Cu-Be alloy). The motivation of the present work is that, at the best of authors’ knowledge, only a limited number of papers on these alloys under high-temperature fatigue are available in the literature and no results deal with notched components. The Cu-Be specimens fatigue data are re-analyzed in terms of the mean value of the Strain Energy Density (SED) averaged over a control volume. Thanks to the SED approach it is possible to summarize in a single scatter-band all the fatigue data, independently of the specimen geometry.

In this paper, a volume criterion based on a simple scalar quantity, the mean value of the strain energy (SED), has been used to assess the static strength of notched components made of Polymethylmethacrylate (PMMA). The local-strain-energy based approach has been applied to a well-documented set of experimental data recently reported in the literature. Data refer to blunt U-notched cylindrical specimens of commercial PMMA subjected to static loads and characterised by a large variability of notch tip radius (from 0.67 mm to 2.20 mm). Critical loads obtained experimentally have been compared with the theoretical ones, estimated by keeping constant the mean value of the strain energy in a well-defined small size volume. In addition, some new tests dealing with V-notched specimens with end holes have been carried out to investigate the effect of the notch opening angle.

In this research, the flow stress of dual layer austenitic-martensitic functionally graded steels (FGSs) under hot deformation loading has been modelled considering the Zener-Hollomon constitutive equations as a function of temperature and strain rate. Functionally graded austenitic-martensitic steels consist of austenite (?) and martensite (M) phases placed on each other in different configurations and produced via Electro Slag Remelting (ESR). The boundary layers properties are obtained by experimental investigation on single phase materials. Finally, the theoretical model is compared with the experimental results measured in the temperature range 1000-1200 °C and strain rate 0.01-1 s-1 and a good agreement is found.

Functionally Graded Steels (FGSs) are possible solutions to improve the properties of steels made by Martensite and Bainite brittle phases. These phases are usually present in the interface between the carbon ferritic steel and the stainless austenitic steel. FGSs materials are widely investigated in the recent literature but only few works have been devoted to investigate the impact energy in the case of crack arresters. To partially fill this gap, the effect of the distance between the notch tip and the position of the median phase on the Charpy impact energy is investigated in the present paper. The results show that when the notch apex is close to the median layer the impact energy reaches its maximum value due to the increment of the absorbed energy by plastic deformation ahead of the notch tip. On the other hand, when the notch apex is far from the median layer, the impact energy strongly decreases. Keeping into account the relationship between the Charpy impact energy and the plastic volume size, a new theoretical model has been developed to link the composite impact energy with the distance from the notch apex to the median phase. The results of the new model show a sound agreement with previous results taken from the literature.