I am reading the paper of Prof. Nishioka (2001) (Int. Jour. of Solid and Fracture, Vol. 38, 5273-5301). He said that "At the earlier stage of crack deceleration, dot(KID) is positive and linear relation with crack tip velocity". I do not understood that meaning. This is from mathematical, right? If after the earlier stage of crack deceleration, which relation between dot(KID) and crack tip velocity?

Dear Alls;

I am loking for the paper which said the Dynamic fracture toughness of PMMA decreases with crack velocity under impact loading, but after crack starts propagation, crack velocity is a decreasing function with crack propagation length.

So, if you know the paper which related to that problem, Could you please show me its title?

Thank you very much,

Best Regards,

 Chau

Dear All,

 I am confusing about the difference of One-point bend specimen and three-point bend specimen.

What is the diffrence of these above pre-crack specimens (mode_I) under impact loading?

Thanks,

Regards,

Chau