We are studying the effect of combine (Shear and tension) loading on failure of Metallic structure (Aluminum and mild Steel). We observed that failure strain in Pure shear is higher than the Pure Tension loading. Though stress developed in the Pure tension loading is higher than the Pure shear loading. I do not able to understand the proper reason behind this.
Hi,
It can depend on your material microstructure. Grain size and grain boundaries can significantly affect the strain behavior of any metal. When you apply shear load, the grain can slide on top of each other while, when you apply tensile load, the fracture mechanism is totally different.
Hello man.
Pure shear as pure tension depends of an area. Will be interesting you observe if your shear area is bigger than tension area. Considering that your are applying the same value to both loading (shear and tension), these areas will impact.
I hope to help you.
Hello Gilberto,
Area in Pure tension and Pure shear is same. But In the case of pure shear failure strain is higher than pure tension case. Area is same for the both case. The main concern is the failure strain.
Hi,
It can depend on your material microstructure. Grain size and grain boundaries can significantly affect the strain behavior of any metal. When you apply shear load, the grain can slide on top of each other while, when you apply tensile load, the fracture mechanism is totally different.
Are you using torsion to apply the shear loading, because any other means of developing shear stresses means you don't have "pure shear" - there will always be some non-zero normal stress. The interaction of normal and shear stresses will affect the fracture strain (not the same mechanism as how normal and shear stresses affect the onset of plasticity, but suffice to say you can't ignore the interaction).
Fracture strain in ductile metals is dependent on many variables - I don't think there is consensus in the the literature about this topic. An area you could look at is research by Bai and Wierzbicki related to fracture dependence on stress triaxiality and Lode angle (Article A comparative study of three groups of ductile fracture loci...
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Unqualified Comment: The formulas or analytical models for estimating stress per unit strain should be used carefully, where one should also examine it from a work/energy sense.
Well, in short the area of influence both in tension and shear varies but you assume it does not. Once you determine its "why and how", then you can get your answer.
Hello
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With a wish for a rudimentary research.
Emil Yankov
I am not sure how you could compare the two together. They are not "defined" on equal basis. Shear strain relates to angle change, while tensile strain relates to dimensional change. Even comparing slip on shear planes with tensile strain is not logical. So, the idea that "this" is higher than "that" is not sound. What you could do to compare is probably relate each strain to its yield value, then compare ratios.
The question does not make sense.
We're talking about "strain," not about "stress," isn't it?
Both do not have an unit of measure.
However, normal (tensile) strain epsilon_x is usually expressed in [mm / m] or [%] and shear strain gamma_xy in [rad].
How can you compare [%] to [radians]?
Hi, I am afraid the question is not perfectly clear. Yet, as Reuben did, I would propose to have a look at the work of Wierzbicki et al., who studied the influence of triaxiality of the stress state. A number of publications that were of use to me (ballistic impact) can be found in the file in attachment.
I agree with Frederik Coghe. You should look into the influence of stress triaxiality and Lode parameter on ductile fracture. The fracture strain will depend on both stress state and Lode parameter.
See for instance this work by Gruben et al: : Article Evaluation of uncoupled ductile fracture criteria for the du...
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