Читать книгу Materials for Biomedical Engineering - Mohamed N. Rahaman - Страница 142

In designing with polymers, the property of viscoelasticity must be taken into account. For applications in which a tensile load is present, for example, data for the tensile strength and creep modulus over the appropriate range of conditions such as stress, time scale, and temperature are relevant. If the polymer degrades in vivo, the effects of environmental conditions should also be taken into account. Designing to avoid yielding of the polymer is often straightforward once the time and temperature dependence of the yield strength is accounted for. In comparison, designing to avoid brittle fracture is more difficult due to the presence of flaws such as microcracks and pores (Section 4.2.5).