III Международная студенческая научная конференция Студенческий научный форум - 2011

A survey of literary sources, to analyze the long-term durability of materials and elements of them, there are basically two alternative approaches: mechanical (benchmarking) and kinetic.
Under the first approach, we introduce a generalized condition of destroyed material: where some combination of the components of the stress or strain; (objective indicator of strength;  invariants of the stress-strain state).The function f depends on the accepted theory
strength or given empirically, and then the function contains parameters, determined experimentally.

According to the second (kinetic) approach, the destruction seems like gradually developing in time change the microstructure of particles of the body under a load. Such an approach takes on special significance in connection with the growing use of structures of composite materials based on polymers that have the task of forecasting performance is complicated because of the irreversible and reversible process changes the molecular and supramolecular structures during operation. In this paper we propose a model of destruction (the relations connecting parameters of efficiency at the time of fracture characteristics
material), based on the relationship of both these approaches to allow for the dependence of the limiting critical conditions at which the destruction, the time of stress, temperature
environmental exposure, exposure, etc. This is especially typical for polymers .
To build a relationship of the proposed mathematical model of fracture
consider a number of hypotheses.
1. The strain tensor can be represented as a sum of tensors of elastic deformation of inelastic deformationTo build a relationship of the proposed mathematical model of fracture
consider a number of hypotheses.
1. The strain tensor can be represented as a sum of tensors of elastic deformation of inelastic deformation.

2. To describe the strain state and fracture in the framework of a generalized model of inelasticity is necessary to consider the history of deformation of the sample depends on the loading path and on time. For different loading paths for the processes of varying duration results will be different.

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