Effects of vibration frequency on fatigue crack propagation of a polymer at resonance

✍ Scribed by A.J. Dentsoras; E.P. Kouvaritakis

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 304 KB
• Volume: 50
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(94)00226-8

✦ Synopsis

Fatigue crack propagation at resonance for polymers is studied. A simple cracked beam vibrates under an external excitation force with constant amplitude and frequency. The well-known equation of Paris is used, which relates the crack propagation rate with the variation of the stress intensity factor range. The influence of external excitation frequency on the mechanical properties of the material, such a complex elastic modulus and loss factor is taken into account.

In a cracked system, natural frequencies change due to a crack. The depth of the crack determines the local stiffness introduced by the crack, which in turn influences the dynamic response of the system. When the crack propagates, the dynamic behavior of the system changes. As a consequence, there is a gradual shift away from resonance.

It is proved that the excitation frequency plays a major role in the determination of the stress intensity factor range, the crack propagation rate and the final number of fatigue cycles to fracture.