Viscoelastic behavior of opto-mechanical properties and its application to viscoelastic fracture studies

• Published in: International journal of fracture 1986-12, Vol.32 (4), p.265-283
• Main Authors: KIM, K.-S, DICKERSON, K. L, KNAUSS, W. G
• Format: Article
• Language: English
• Subjects: Applied sciences; crack propagation; Exact sciences and technology; mechanical properties; Organic polymers; Physicochemistry of polymers; polymers; Properties and characterization; strain; stress; stress strain relations; viscoelasticity
• ISSN: 0376-9429; 1573-2673
• DOI: 10.1007/BF00018545

In experimental fracture studies of viscoelastic polymers presently available optical measurement methods need to be modified to account for the rate sensitivity of the physical properties. Here, photoviscoelastic behavior is examined for the purpose of determining the mechanical state of stress and strain at the tip of a crack moving through a viscoelastic solid. The linearly opto-mechanical constitutive relation is derived from mechanical and dielectric relaxation functions for thermorheologically simple solids. Computations of the caustic, based on the square root singular stress field at the tip of a steadily propagating crack show that the crack speed has a pronounced effect on the size of the caustic but leaves the shape virtually unchanged. A knowledge of the phenomenological opto-mechanical properties of the polymer allows thus the determination of the stress intensity factor in (linearly) viscoelastic solids.