Strength degradation predictions

There are only a few models established for predicting strength degradation. A similar mathematic function as Eq. (5.3) was used to express the relationship between strength and temperature using the semiempirical equation [16, 18], as shown in Eq. (5.14) ... 

The time-to-failure of a structure or its components is an important issue for structural safety considerations in fire. On the basis of the strength degradation models for FRP materials under elevated and high temperatures developed in Chapter 5, the time-to-failure is predicted for GFRP tubes and laminates under both thermal and mechanical loading in compression. Temperature responses were again calculated using the thermal response model presented in Chapter 6. 

A model for predicting the compressive strength degradation of FRP materials in fire was applied as proposed in Chapter 5. Similarly to the modeling for stiffness degradation, it assumes that an FRP material at a certain temperature can be... 

This equation could be useful in predicting strength degradation in ceramics subjected to hits by sharp particles when in normal use. 

The objective of the current work was to compare FOD behavior between the SiC/SiC and the oxide/oxide CMCs in terms of impact morphologies and strength degradation, based on the previous work [1-2], In addition, the response to static indentation of the two composites with respect to deformation was also characterized using the same steel balls that were employed in the previous FOD testing. The static indentation results were then used in order to make an attempt of quasi-static prediction of impact force as a function of impact velocity involved in the FOD testing. 

Service lifetime prediction of polymers and/or polymer based materials may be undertaken from different types of tests, such as creep behavior tests (linear and non-linear creep, physical aging, time-dependent plasticity), fatigue behavior tests (stress transfer and normalized life prediction models, empirical fatigue theories, fracture mechanics theory and strength degradation) and standard accelerated aging tests (chemical resistance, thermal stability, liquid absorption) [32]. 

Data was collected over a two-year period on the effect of water on DuPont s Zytel 101. In an Arrhenius plot of this data the failure point was the time when the elongation and impact strength started to decrease. This is not a chemical degradation, but rather a permeation or diffusion rate phenomenon. It shows that high temperature water tests can be used to predict normal temperature exposure results. 

Figure 9.2 Schematic prediction of strength of a polyester geotextile subjected to slow degradation by hydrolysis (based on information from [6])...

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