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When the elastic‐brittle cracked body is subjected to compressive‐shear loading, not only does the phenomenon of wing crack initiation and propagation occur, but there is also a notable incidence of secondary crack initiation and propagation due to shear stress. Moreover, the shear fracture toughness (KIIc) predicted by the fracture criterion in the framework of classical fracture mechanics is usually smaller than the tensile fracture toughness (KIc), which is inconsistent with the actual observations. Therefore, this research firstly establishes a mechanical model of an elastic‐brittle cracked body under biaxial compression considering three kinds of crack parameters and materials' mechanical properties. Then, the stress field characteristics at the crack tip are analyzed. Next, a compression‐shear mixed fracture criterion is proposed. Finally, the effects of the lateral pressure coefficient (λ), critical plastic zone size (rc), friction coefficient (f), and deformation parameters of the crack surface on the failure modes at the crack tip are investigated. Highlights: A distinction is made between the failure and loading modes of the cracked rock mass.The stress field at the crack tip under compression and shear conditions is analyzed.A compression‐shear fracture criterion related to KIc and KIIc of materials is proposed.Conditions for the occurrence of shear failure at the crack tip are discussed. [ABSTRACT FROM AUTHOR]

A new test specimen is proposed for investigation of mixed mode I/II/III fracture of materials. In the test specimen, by displacing the position of an inclined crack from the middle of the rectangular specimen, in addition to mode II loading, mixed mode I/III loading conditions are created under anti‐symmetric four‐point bending. To examine the applicability of the test set‐up, the specimens made of PMMA (polymethyl‐methacrylate) with three crack angles and three different positions of crack with reference to the middle of the specimen are tested. The experimental fracture loads are compared with the theoretical predictions of the maximum principal stress fracture criterion. There is a satisfactory consistency between the test and theoretical results. Although the proposed test configuration has limitations in applying the mixed modes of I/III and II/III, it is an efficient test configuration easier and less expensive than other configurations utilizing complex crack geometry or complicated loading fixtures. Highlights: A new test specimen under ASFPB loading is proposed to test mixed‐mode I/II/III fracture.Both FE analysis and experiments are used to assess the test specimen for fracture study.Good agreement of the experimental results with the fracture criteria is reported.The method is simple and cheap, but unable to test mixed‐modes I/II, and II/III fracture. [ABSTRACT FROM AUTHOR]

Considering T‐stress components under compression, the crack initiation characteristics of HT200 and PMMA under uniaxial compression have been investigated by theoretical analysis and experimental study for central cracked plate (CCP) and compact tension shear (CTS) specimens with I‐II mixed mode crack. Crack initiation angles of CCP and CTS specimens under compressive load were theoretical predicted according to modified maximum tangential stress (MMTS) criterion and modified maximum shear stress (MMSS) criterion. The influence of material parameters and specimen geometrical configurations on crack initiation characteristics was illustrated through experiments. It demonstrates that the modified fracture criterion considering T‐stress components is more consistent with experiments. Crack initiation angle is related to material properties. Limit load PL is controlled by KII under compression for CCP specimen, and PL of PMMA is less than that of HT200. The closure effect on CTS specimens is less significant than that on CCP specimens. Highlights: Crack initiation angle of closed crack is related to material properties.Limit load PL is controlled by KII under compression for CCP specimens.The closure effect on CTS specimens is less significant than that on CCP specimens. [ABSTRACT FROM AUTHOR]

Biaxial (axial and torsional loading) static tests were performed for the first time on EN‐GJS‐600–3 ductile cast iron tubular specimens obtained reproducing the solidification conditions typical of thick‐walled castings. The experimental results were elaborated to determine the yield and fracture loci of the material, which exhibited significant deviations from those predicted by the von Mises and Mohr–Coulomb criteria usually adopted for steels and gray cast iron, respectively. For this purpose, several alternative criteria proposed in the technical literature, some of them specifically devised for composite materials, have been calibrated and compared to account for the peculiar mechanical properties of this natural composite material. [ABSTRACT FROM AUTHOR]

In this study, the rupture load in rubbers weakened by sharp V‐notch is investigated under mode I loading. To this end, first, mode I fracture tests are performed on V‐notched samples made of styrene‐butadiene rubbers and the corresponding rupture loads are obtained. Then, the effective stretch (ES) criterion, which was recently developed by the present authors for rupture assessment of cracked rubber parts, is extended and used for the V‐notched rubbers. It is shown that similar to cracked rubbers, the state of stress near the notch tip is also nearly uniaxial. By employing the ES criterion, the critical displacements corresponding to the rupture in the tested samples are calculated. Finally, the predictions of the criterion are compared with the corresponding experimental values, and good consistency is shown to exist. [ABSTRACT FROM AUTHOR]

In this contribution, we attempt to give a general methodology allowing the fracture prediction of polymers under biaxial monotonic loading. Using the intrinsic defect concept, we assume that fracture at a macroscopic level is the consequence of the presence of defects at lower scales. We also assume that the fracture is governed by a macroscopic parameter, the strain energy release rate or the J-integral. Intrinsic defect size, constitutive response and fracture toughness being the criterion inputs; the principal stretches at break can be therefore estimated for any biaxial and monotonic loading path. The proposed methodology includes the estimation of the J-integral for any biaxial loading using a unified expression of this parameter which is a generalised form of that developed in the literature for uniaxial tension. Using different set of experimental data obtained in our team, the methodology is then successfully applied to various kinds of polymers: a natural rubber, a styrene-butadiene rubber, a polyurethane, a thermoplastic elastomer and a high-density polyethylene. We show also that such a methodology can be applied to predict the ageing effects on the stretches at break. [ABSTRACT FROM AUTHOR]

In this paper, we advanced a new interval reliability analysis model for fracture reliability analysis. Based on the non-probabilistic stress intensity factor interference model and the ratio of the volume of the safe region to the total volume of the region associated with the variation of the standardized interval variables is suggested as the measure of structural non-probabilistic reliability. We use this theory to calculate the reliability of structure based on fracture criterion. This model needs less uncertain information, so it has less limitation for analysing an uncertain structure or system. Examples of practical application are given to explain the simplicity and practicability of this model by comparing the interval reliability analysis model with probabilistic reliability analysis model. [ABSTRACT FROM AUTHOR]

This article summarises the uniaxial tension tests for 20 notched bars fabricated from high strength steel Q345 specified in Chinese National Standards. The effects of the notch radius, r, and that of the notch depth ratio, , on the ductility and fracture resistance of this high strength steel are examined. The experimental data are further analyzed using a generalized yield model together with an elliptical fracture stress envelope originally proposed by the first author. The experimental results demonstrate that cracks initiate at the notched section, with the fracture surface filled with many dimples and shearing marks. Specimens with a sharper notch radius (a smaller r) and a larger notch depth (a smaller ratio) show poor ductility, but high fracture strength. The stress field computed from the numerical procedure including the generalized yield model indicates that the crack initiation occurs at the centre of the notched section which experiences the highest stress triaxiality ratio . As the stresses at the notched section reach the limiting values determined from the elliptical fracture criterion, macroscopic fracture failure in the notched bar occurs. [ABSTRACT FROM AUTHOR]

The topic of the paper is the extension of the Maximum Circumferential Tensile Stress Criterion to orthotropic materials, to obtain the crack initiation angle and the fracture loci. It includes the effects of orthotropy, load biaxiality and non-singular terms. It requires the solution of the elastostatic problem of an orthotropic plate having a central inclined crack and subjected at infinity to a uniform biaxial load. It is assumed that the crack line does not coincide with an axis of elastic symmetry of the body. The original problem has been transformed by rotation into a system of coordinates with one axis along the crack. The effects of the rotation of the reference system on the stress–strain equations as well as on the equilibrium equations have been considered. The stress field is represented in terms of two potential functions and the crack problem is solved by means of the superposition principle. [ABSTRACT FROM AUTHOR]