1- (25 pts) The nodal coordinates and the nodal displacements for some plane stress elastic element is listed in the following problem. The element is 0.1 m thick. The coordinates and displacements are given in meters. (a) Calculate K(1,1) of the element stiffness matrix (b) Calculate the element stress x = 2 Y = 2 U = 0.003 V = 0 D = 106 4 0 N = N = 1 = 23 3 az = X31 13 = 12 - 21 N3 = [16 4 0 16 0 (N/m) 0 6 1 -(a + bx + cy) 2A 1 -(a + bx + cy) 2A 1 -(a3 + b3x + c3y) 2A b = y2 - Y3 b = y3 - Y b3=Y-Y2 x = 1 y = 1 V = 0.001 V = -0.003 C = x3 - X2 C = X1 X3 C3 = x2-X1 X3 = 1 Y3 = 0 U3 = 0.0015 V3 = 0.0