Fracture Mechanics of Polymers

analysis approximation assume behaviour bending brittle Charpy cm/min computed condition constant load crack front crack growth crack length crack propagation crack speed crack tip craze stress criterion curves decreases deduced defined deformation density determined displacement ductile tearing E₁ E₂ effects elastic elliptical energy dissipation energy release rate expression failure fatigue fracture mechanics Fracture toughness fully plastic function geometry give HDPE homopolymer impact test increases K₁ K₁₁ KC MPa√m kg/m³ kinetic energy kJ/m² ligament area line zone linear load-deflection material methanol modulus MPa/m occur parameter plane strain plane stress plotted PMMA polymers reference result rubber Section shear shown in Fig shows sin² solution specimen stable strain energy stress field stress intensity factor surface temperature tension thickness transition U₁ unstable values velocity versus visco-elastic yield stress Δα πα