POROSITY EFFECTS ON NONLINEAR STATIC PERFORMANCES OF FUNCTIONALLY GRADED SHELLS CONSIDERING THICKNESS STRETCHING. - Mallek, Hanen; Mellouli, Hana; Said, Lotfi Ben; Wali, Mondher; Dammak, Fakhreddine; Alhadri, Muapper (Facta Universitatis, Series: Mechanical Engineering, 2025)