Problem 1. A 0.9-m-long and 0.2-m-wide rectangular sandwich plate is made of a 0.02-m-thick core covered on both sides by graphite epoxy facesheets. The material properties are 0 Longitudinal E1 148 +45 16.39 Young's modulus (GPa) Transverse Young E2 9.65 16.39 modulus (GPa) Longitudinal shear G12 4.55 38.19 modulus (GPa) Longitudinal V12 0.3 0.801 Poison's ratio Thickness (mm) ho 0.1 0.2 L = 900 mm k SS SS SS y SS No < L= 200 mm t = 2 mm d = 22 mm c = 20 mm t = 2 mm The layup of each facesheet is [452/012/ 452], and the thickness of each facesheet is 0.002 m. The 0 plies are parallel to the short edge of the plate. The plate, simply supported along all four edges, is subjected to uniform compressive loads along the long edges. Calculate the buckling load. The core is isotropic (Ec = 2106 kN/m, vc =0.3).