Bruhn - Analysis And Design Of Flight Vehicles Structures Episode 3 part 6

Tham khảo tài liệu 'bruhn - analysis and design of flight vehicles structures episode 3 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | ANALYSIS AND DESIGN OF FLIGHT VEHICLE STRUCTURES Illustrative Problems in Calculating Crippling Stresses. __ 05 NJ. 16 Fig. a Area .093 Problem 1. Find the crippling stress for the equal leg angle shown In Fig. a. The material is aluminum alloy 2Ũ24-T3. Solution by Method 1. T Material properties are - p Fpv 40000 En 10 700 000 -1 Fig. a For this method we use Fig. . The parameter for bottom scale of Fig. Is a b 2t where a and b are leg lengths measured to centerline of adjacent leg of angle. .For our case a b 1 - .025 . Thus a b 2t . From Fig. using on lower scale and the curve for two edges free we read on the left hand scale that Fcc FCyE .0330. Since we have only one angle the crippling stress Fes Fcc .0330 X 40 000X 10 700 000 21600 psi. Solution by Method 3 Gerard Method For angle sections we use equation . A plot Of this equation is given In Fig. . The parameter for lower scale Is A Fqv X 3 tmer r where A section area and g feV ù equals the number of flanges plus cuts or g s 2 for an angle section. Substituting 99 .-J. 40 000 1 a . ._g X .05aM 10 700 000J Using this value in Fig. we read Fcg FCy - . Therefore Fcg - X 40 000 20 000 psi. Problem 2. Same as Problem 1 but change material to aluminum alloy 7075-TS. FCy X 67 000 Ec - 10 500 000 Solution Method 1. Fcs Fcc .0330 67000x 10 500 000 2S 000 psi Solution by Method 2. f f 093 I 000 x a JQ - 2 X .05s 10 500 000 1 485 From Fig. Fcs Fỡy whence Fcs - .43 X 67 000 - 26800 psi. Problem 3. Same as Problem 1 but change material to Titanium Tl-afii. FCy - 110 000 Ec 15 500 000. Solution Method 1. Fcs - Fcc .0330 110 000 X 15 500 000 43000 psi Solution Method 2. .093 110 000 1 e 2 X 15 o00 000 From Fig. Fcs FCy whence Fcs X 110 000 41 800. Problem 4. Find the crippling section shown in Fig. b aluminum alloy 2024-T3 Ec - 10 700 000. stress for the channel If the material Is Fcy 40 000 Solution Method 1. As shown In .