Initial yielding and fracture in notched sheet molybdenum

Ault, R.T.; Spretnak, J. W.

doi:10.1016/0020-7403(65)90068-8

Cited by 12 publications

(7 citation statements)

References 4 publications

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“…As a consequence of the triaxiality of the stress distribution in the plastic enclave, measurements of the dimensions of the plastic zones even in perfectly plastic materials show that their dimensions and especially their length are always smaller than those given by the DB-model [6,7]. Besides, the experimental results, given in the paper by Dugdale [4], where an elasticperfectly plastic material was tested, showed that, for a certain loading step and beyond, the experimentally defined plastic zones are always shorter than those anticipated by the model.…”

Section: The Necessity To Modify the Db-modelmentioning

confidence: 97%

“…The problem was solved only for the case of antiplane shear applied at infinity of the cracked plate. Thus, Ault and Spretnak [6] studied the plastic zones developed at the bottoms of sharps notches in tension specimens made of molybdenum and found that the lengths of these zones differ considerably from the lengths given by the DB-model. However, for the important case of a cracked plate subjected to pure tension at infinity (opening mode of fracture) a convenient solution is by using the Dugdale-Barenblatt model [-4, 5].…”

Section: Introductionmentioning

confidence: 99%

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The modified Dugdale-Barenblatt model adapted to various fracture configurations in metals

Theocaris

Gdoutos

1974

Int J Fract

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A B S T R A C TThe Dugdale-Barenblatt model is extended to encompass the influence of strain hardening on the plastic enclaves developed at the tips of a crack in a plate subjected to tension at int'mity. While in the DB-model the distribution of internal stresses along the plastic zone in the extension of the crack length was taken constant and equal to the yield stress, in the modified version of this model this distribution is taken variable with a minimum value the yield stress (a0) and a maximum value (~rm~), depending on the loading step and the amount of strain-hardening of the material. Six different configurations of stress distribution in the plastic enclaves were considered with various values of the ratio Crm~,/a o. For each stress configuration and for various loading steps the shape of the respective caustic corresponding to the singularity created at the plastic zone near the crack tip was computed by modifying appropriately Dugdale's theory to each of the six configurations in the plastic enclave. The caustic was formed by reflections of a parallel coherent light beam at the vicinity of the crack-tip.Three different types of steel were examined with different stress-strain relations and different amounts of strainhardening, By comparing the shapes of the theoretically derived caustics by using each of the stress configurations of the modified DB-model with the shapes of the experimentally obtained caustics for the corresponding loading step it was possible to adapt the DB-model to each case of material, to disclose the influence of strain-hardening on the fracture mode of the material and to indicate the most probable profile of stress distribution in the plastic zone as the loading is increased and further plastic deformation is established in the specimen. Interesting results have been revealed on the influence of strain hardening in the fracture mode of metals.

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Section: The Necessity To Modify the Db-modelmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

The modified Dugdale-Barenblatt model adapted to various fracture configurations in metals

Theocaris

Gdoutos

1974

Int J Fract

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“…It has been observed in tests with cracked steel plates, that the plastic zone has a wedge shape [6,7,8]. Ault and Spretnak [9] with sharp notches, and Gerberich [10] with cracks in several aluminum alloys have detected that the plastic area has a circular shape.…”

Section: Literature Reviewmentioning

confidence: 99%

“…Equation (3)(4)(5)(6)(7)(8)(9)(10) indicates that the constrained zone around the crack tip subjected to mixed mode deformation is a circle of radius r^ and is function of the distance and the model thickness d. Using…”

Section: Literature Reviewmentioning

confidence: 99%

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Study of mixed mode stress intensity factors using the experimental method of caustics

Younis

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Stress intensity factors in yielding materials by the method of caustics

Theocaris

1973

Int J Fract

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A B S T R A C T The method of caustics, as it has been developed by the author, was applied up to now to evaluate the stress-intensity factors in cracked plates under conditions of generalized elastic plane stress [1]. According to this method the partially reflected light beam either on the front or on the rear face of a polished cracked plate was deviated at the vicinity of the crack-tip because of the large constraint at this area, due to the Poisson effect and created a caustic. It was shown that the dimensions of the caustic are directly and intimately related to the values of the stress-intensity factor components. In this paper the theory developed for the elastic case of loading was extended to incorporate the case of a yielding material at the vicinity of the crack-tip, which can be represented by the Dugdale--Barenblatt cohesive force model, and presents a stress-strain curve resembling an elastic perfectly-plastic material. The equations for the initial curve engendering the caustic and the generalized epicycloid, which represents the caustic, were established. It was shown that at the early stage of yielding, at the vicinity of the crack-tip, the typical shape of a quasi-circular caustic appears, which later on, in a higher step of loading, evolutes to the well-known shape of the plastic wedge-shaped zone. Experimental evidence with steel and plastic specimens corroborated the theoretical results.

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Initial yielding and fracture in notched sheet molybdenum

Cited by 12 publications

References 4 publications

The modified Dugdale-Barenblatt model adapted to various fracture configurations in metals

The modified Dugdale-Barenblatt model adapted to various fracture configurations in metals

Study of mixed mode stress intensity factors using the experimental method of caustics

Stress intensity factors in yielding materials by the method of caustics

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