III Международная студенческая научная конференция Студенческий научный форум - 2011
ANALYSIS QF STRESS-STRAIN CURVES
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Analysis of experimental data suggests characteristics of the temperature dependence of relaxation processes and fracture for viscoelastic polymers with the same energy value activation for each material.
Both aspects of the strength of polymers (short-term and long-term loading) depend on the local structural changes that primarily can be linked with the process of accumulation of damage, education grid hairline cracks. Combining different approaches to describing these processes, ie formulation of a general theory of deformation and fracture of polymers depends on the study of the relationship of deformation, destruction and action voltage, temperature, aggressive factors in the whole time interval of operation of the element.
Relaxation properties influence the process of destruction, enhancing the growth of microdamage. This is explained by the fact that in the process of development forced highly elastic deformation near the damage is mechanical energy into heat. An examination of these experimental data one can draw conclusions that should be taken into account when constructing the conditions of fracture:
1.Mehanicheskie properties and the process of destruction of polymer materials substantially depend on time and operating conditions.
2. Destruction is a two-stage process. At the first stage of degradation of the properties of the material, the accumulation of damage, microcracks occur. The stage ends at a time when the merger of microdamage formed macroscopic crack. This moment is short-lived and by their physical nature is a loss of stability of equilibrium microdefects .
3. At failure, the material from corrosion or silent creep value of the first stage is so large that the evaluation time of destruction the destruction process can be generally described as the accumulation of damage and degradation properties of plastic.
4. Given the irreversibility of the process of destruction is determined not only the current values of parameters characterizing it, but the entire prior history of these parameters.
Both aspects of the strength of polymers (short-term and long-term loading) depend on the local structural changes that primarily can be linked with the process of accumulation of damage, education grid hairline cracks. Combining different approaches to describing these processes, ie formulation of a general theory of deformation and fracture of polymers depends on the study of the relationship of deformation, destruction and action voltage, temperature, aggressive factors in the whole time interval of operation of the element.
Relaxation properties influence the process of destruction, enhancing the growth of microdamage. This is explained by the fact that in the process of development forced highly elastic deformation near the damage is mechanical energy into heat. An examination of these experimental data one can draw conclusions that should be taken into account when constructing the conditions of fracture:
1.Mehanicheskie properties and the process of destruction of polymer materials substantially depend on time and operating conditions.
2. Destruction is a two-stage process. At the first stage of degradation of the properties of the material, the accumulation of damage, microcracks occur. The stage ends at a time when the merger of microdamage formed macroscopic crack. This moment is short-lived and by their physical nature is a loss of stability of equilibrium microdefects .
3. At failure, the material from corrosion or silent creep value of the first stage is so large that the evaluation time of destruction the destruction process can be generally described as the accumulation of damage and degradation properties of plastic.
4. Given the irreversibility of the process of destruction is determined not only the current values of parameters characterizing it, but the entire prior history of these parameters.
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