An equation governing the initiation and growth of quasi-static fracture in a linearly viscoelastic material is derived using the thermodynamic power balance as a fracture criterion. It is found that this equation does not involve the time-dependent part of the viscoelastic material behavior but only the elastic portion. This is in direct contrast to the results obtained by Williams [1], Cherepanov [3, 4], and Knauss [5], all of whom use the same assumptions and fracture criterion as does the present paper. The apparent errors made in [1, 3-5] are pointed out and it is shown how, when the appropriate corrections are made, the results in each case become identical to those obtained in the present paper.

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