Materials failure theory, strain energy, and the principal stresses eigenvalue problem: how these three historical areas are interrelated and mutually reinforcing, thus enabling new results for materials failure

2018 ◽  
Vol 24 (7) ◽  
pp. 2116-2125
Author(s):  
Richard M Christensen
2015 ◽  
Vol 83 (2) ◽  
Author(s):  
Richard M. Christensen

A recently developed ductile/brittle theory of materials failure is evaluated. The failure theory applies to all homogeneous and isotropic materials. The determination of the ductile/brittle transition is an integral and essential part of the failure theory. The evaluation process emphasizes and examines all aspects of the ductile versus the brittle nature of failure, including the ductile limit and the brittle limit of materials' types. The failure theory is proved to be extraordinarily versatile and comprehensive. It even allows derivation of the associated ductile/brittle transition temperature. This too applies to all homogeneous and isotropic materials and not just some subclass of materials' types. This evaluation program completes the development of the failure theory.


1998 ◽  
Vol 120 (4) ◽  
pp. 721-726
Author(s):  
K. Deb

Determination of overall factor of safety of a design involves repeated calculation of factor of safety at critical points in the design. For a given stress state at a point, the factor of safety is calculated by first finding the principal stresses and then comparing them with the maximum safe stress that can be applied without causing failure of the material according to an appropriate failure theory. In this paper, we suggest quick and ready-to-use expressions and graphs for calculating factor of safety for biaxial stress states for a number of commonly-used failure theories. These graphs can be directly used as design charts for computing factor of safety in engineering design activities.


2016 ◽  
Vol 83 (11) ◽  
Author(s):  
Richard M. Christensen

The history of developing failure criteria is briefly examined. The cumulative result is found to be completely unsatisfactory and extremely misleading, to the point of crisis. The long time blockage of the materials failure field has had serious and retarding effects on all related technical areas that are dependent on reliable failure projections. A new and rationally different approach to failure theory formulation is outlined and fully documented. After summarizing recent research progress, a program for the recovery and revitalization of the field is given.


1957 ◽  
Vol 24 (1) ◽  
pp. 109-114
Author(s):  
M. L. Williams

Abstract In an earlier paper it was suggested that a knowledge of the elastic-stress variation in the neighborhood of an angular corner of an infinite plate would perhaps be of value in analyzing the stress distribution at the base of a V-notch. As a part of a more general study, the specific case of a zero-angle notch, or crack, was carried out to supplement results obtained by other investigators. This paper includes remarks upon the antisymmetric, as well as symmetric, stress distribution, and the circumferential distribution of distortion strain-energy density. For the case of a symmetrical loading about the crack, it is shown that the energy density is not a maximum along the direction of the crack but is one third higher at an angle ± cos−1 (1/3); i.e., approximately ±70 deg. It is shown that at the base of the crack in the direction of its prolongation, the principal stresses are equal, thus tending toward a state of (two-dimensional) hydrostatic tension. As the distance from the point of the crack increases, the distortion strain energy increases, suggesting the possibility of yielding ahead of the crack as well as ±70 deg to the sides. The maximum principal tension stress occurs on ±60 deg rays. For the antisymmetrical stress distribution the distortion strain energy is a relative maximum along the crack and 60 per cent lower ± 85 deg to the sides.


1988 ◽  
Vol 110 (3) ◽  
pp. 185-189 ◽  
Author(s):  
D. Elad ◽  
A. Foux ◽  
Y. Kivity

The nonlinear elastic response of large arteries subjected to finite deformations due to action of biaxial principal stresses, is described by simple constitutive equations. Generalized measures of strain and stress are introduced to account for material nonlinearity. This also ensures the existence of a strain energy density function. The orthotropic elastic response is described via quasi-linear relations between strains and stresses. One nonlinear parameter which defines the measures of strain and stress, and three elastic moduli are assumed to be constants. The lateral strain parameters (equivalent to Poisson’s ratios in infinitesimal deformations) are deformation dependent. This dependence is defined by empirical relations developed via the incompressibility condition, and by the introduction of a fifth material parameter. The resulting constitutive model compares well with biaxial experimental data of canine carotid arteries.


Author(s):  
Richard M. Christensen

It is reasoned that any materials failure theory that claims generality must give full account of ductile versus brittle failure behaviour. Any such proposed theory especially must admit the capability to generate the ductile/brittle transition. A derivation of the failure surface orientations from a particular isotropic materials failure theory reveals that uniaxial tension has its ductile/brittle transition at T / C  = 1/2, where T and C are the uniaxial strengths. Between this information and the corresponding ductile/brittle transition in uniaxial compression it becomes possible to derive the functional form for the fully three-dimensional ductile/brittle transition. These same general steps of verification must be fulfilled for any other candidate general failure theory.


2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Richard M. Christensen

This overview/survey assesses the state of the discipline for the failure of homogeneous and isotropic materials. It starts with a quick review of the many historical but unsuccessful failure investigations. Then, it outlines the dysfunctional current state of the field for failure criteria. Finally, it converges toward the technical prospects that can and very likely will bring much needed change and progress in the future.


2021 ◽  
Vol 89 (1) ◽  
Author(s):  
Richard M. Christensen

Abstract The recently developed general materials failure theory is specialized to the two-dimensional state of plane stress. It takes a form that is virtually no more involved than that of the Mises criterion. Yet it remains applicable to the entire range of materials types and thus retains that generality. The Mises form has absolutely no capability for generality. This plane stress form of the new failure theory reveals the existence of three independent modes and mechanisms of failure, not two, not four, purely three. The Mises criterion has one mode of failure. These three modes of failure are fully examined. It is verified that these modes of failure under plane stress conditions are exactly the same as those operative in the three-dimensional case. The simple plane stress form of the failure theory has major appeal and likely use as a teaching tool to introduce failure and to help de-mystify the vitally important general subject of materials failure.


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