A New Criterion for Rupture Assessment of Rubber‐Like Materials under Mode‐I Crack Loading: The Effective Stretch Criterion

This paper investigates the effects of the first non‐singular stress terms on the fracture assessment of sharp V‐notches under mixed mode loading. First, numerical studies have been performed on a fracture test configuration called single V‐notched ring (SVR) specimen. Then, the notch stress intensity factors as well as the coefficients of the first non‐singular stress terms, which are vital parameters in brittle fracture of V‐notched components, were calculated via a finite element over‐deterministic algorithm for a wide range of loading and geometry conditions. The obtained results demonstrate that the SVR specimen is able to provide a complete range of mode mixities from pure mode I to pure mode II loading conditions. The numerical results, next, have been converted to dimensionless parameters and are illustrated in several graphs. Indeed, these graphs can be easily employed by the engineers for rapid calculation of the corresponding notch stress intensity factors and the coefficients of the first non‐singular stress terms in the SVR specimen. The obtained fracture parameters are then submitted to the maximum tangential stress criterion to assess the effects of the first non‐singular terms on fracture behaviour of the specimen. Finally, an experimental study has been performed on the SVR specimen made of Nayriz Marble rock for two notch angles with a complete range of mode mixities. The obtained experimental data confirm the significant role of the first non‐singular stress terms. In fact, these results show that considering only the singular stress terms may induce an average error of 38% in the predicted fracture loads, which can be decreased to about 12% just by adding the contribution of the first non‐singular terms to the maximum tangential stress criterion.

Section: Introductionmentioning

confidence: 99%

The role of first non‐singular stress terms in mixed mode brittle fracture of V‐notched components: an experimental study

Dehghany

Googarchin

Aliha

2016

“…Therefore, the critical value of the ES, λ ces , can be computed based on the results of the uniaxial tensile test. In this regard, if the final stretch of a rubber in the uniaxial tensile test is equal to λ ten , the value of λ ces for an incompressible rubber can be obtained as follows:

λ_{ces} = \sqrt{\frac{λ_{italicten}^{2} + 2 λ_{italicten}^{- 1}}{3}}

…”

Section: Analytical Formulationsmentioning

confidence: 99%

“…Moreover, due to the unique physics of rubber as stated before, presentation of a fracture criterion considering the rubber physics as the central part of criterion is of paramount importance. In this regard, the present authors recently developed a displacement‐based criterion for rupture prediction of cracked rubbers which is called the effective stretch (ES) criterion …”

Section: Introductionmentioning

confidence: 99%

“…In this regard, the present authors recently developed a displacement-based criterion for rupture prediction of cracked rubbers which is called the effective stretch (ES) criterion. 25,26 A review of literature shows that in addition to the ES criterion, some other criteria have also been presented for fracture prediction of rubbers weakened by cracks (see, for example, literatures [27][28][29][30][31][32][33][34]. However, to the best knowledge of the authors, there is no study concentrated on the rupture assessment of rubber-like materials containing V-notches.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fracture analysis of V‐notched rubbers: An experimental and theoretical study

Heydari-Meybodi

Ayatollahi

Dehghany

et al. 2018

Self Cite

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.

“…Based on the above concept, micromechanics‐based criteria have also been proposed; among such approaches, the chain stretch model assumes the failure to occur when the average molecular chain stretch reaches a critical value; an estimation of the average stretch value has been proposed to be given by

λ_{chain} = \sqrt{((), e^{2 ϵ_{1}} + e^{2 ϵ_{2}} + e^{2 ϵ_{3}}) / 3}

.…”

Section: Failure Of Stretchable Polymeric Materialsmentioning

confidence: 99%

Defect sensitivity of highly deformable polymeric materials with different intrinsic qualities at various strain rates

Brighenti

Carpinteri

Artoni

et al. 2017

Highly deformable materials, such as elastomers and gels, can withstand very large deformation without failure, and this response is usually insensitive to the presence of macroscopic defects. These polymer‐based materials, different from the traditional ones which are usually characterized by an enthalpic elasticity, show a mechanical response which is governed by the state of internal entropy of their molecular network. If fracture energy is large, the noticeable ability of soft materials to rearrange their network at the microscale, to display large deformation and to dissipate energy thanks to their viscoelasticity, allows the minimization of the local detrimental effect of existing flaws. In the present paper, the mechanical behavior of silicone‐based edge cracked plates with different crack sizes and severity of the intrinsic flaws embedded in the material is examined by taking into account the time‐dependent effects. Experimental and theoretical aspects are discussed to explain the defect tolerance of such materials. The detrimental effect of intrinsic voids is quantified, and the beneficial effect due to strain at low rates is analysed. The critical distance is related to the ultimate stretch value, the quality of the material, and the crack size.