Open Access

ARTICLE

Strength Failure Conditions of the Various Structural Materials: Is there some Common Basis existing?

by ,

1 Prof. Dr.-Ing. habil. Ralf G. Cuntze, formerly MAN Technologie AG, Augsburg, Germany. D-85229 Markt Indersdorf, Tel. & Fax: 0049 8136 7754, E-mail: Ralf_Cuntze@t-online.de

Structural Durability & Health Monitoring 2007, 3(2), 87-106. https://doi.org/10.3970/sdhm.2007.003.087

Abstract

The paper deals with the application of phenomenological, invariant-based strength conditions (fracture failure) and their interrelationships. The conditions have been generated and are just applied here for a variety of materials. These might possess a dense or a porous consistency, and belong to brittle and ductile behaving isotropic materials, brittle unidirectional laminae and brittle woven fabrics. The derivation of the conditions was based on the author's so-called Failure Mode Concept (FMC) which basically builds up on the hypotheses of Beltrami and Mohr-Coulomb.
Essential topics of the paper are: 'global fitting' versus 'failure mode fitting', a short derivation of the FMC, the presentation of the FMC-based strength failure conditions for the material families mentioned above, and the visualization of a variety of conditions. Various links or interrelationships between the materials are outlined.
Conclusions which may be drawn from the laborious investigations: 1. The application of Beltrami's assumption together with the consideration of material friction forms a common basis in the determination of strength conditions. 2. The FMC is an efficient concept because it very strictly utilizes a 'thinking in failure modes' as well as an application of material symmetry-related invariants. It has proven to be a helpful tool in simply fitting the course of multi-axial strength test data, and it finally can capture several failure modes in one equation avoiding the shortcomings of the usual 'global fitting' strength conditions. 3. Different but similar behaving materials can be basically treated with the same strength condition.

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Keywords

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