Can we calculate the following equations in Maple?

Substituting equations (21) and (22) into (17), and then obtain equation (23). How to do that? I have done this, but the results are complex and large. They are not in a sum form, but in an expansion form. The reference and the maple file are attached.

Hope for your help.

Best wishes,

Kang

Dynamic_buckling_of_thin_isotropic_plates_subjected_to_in-plane_impact.pdf

gg.mw