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Tham khảo tài liệu 'lightweight electric hybrid vehicle design episode 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Design for optimum body-structural and running-gear performance efficiency 213 known as tension coefficients is applied. This is based on the fact that proportionality exists between both resolved components of length and of force. A tension coefficient S L Fx X Fy Y Fz Z for member force S in a length L has projecting force vectors and length components Fx Fy Fz and X Y Z on perpendicular coordinate axes. The view at d shows one bay of a space truss that might be an extension used to support an engine gearbox unit behind a monocoque bodyshell structure. For analysis the frame is assumed to have rigid plates at b12 3 4 and c12 3 4 which offer no force reaction perpendicular to their own planes zero axial warping constraint . When considering the torsional load case for the bay b1c1 and b4c4 member forces are zero by resolving at b1 and c4 observing zero axial constraint of the truss. Remaining members the envelope have equal force components F2 at the bulkheads and tension coefficients for all of them are FJZ. This common value can be determined by projecting envelope member forces onto the bulkhead planes as shown. By taking moments about any axis O for any one member c3b4 say with projected length d contribution to torque reaction is rtd half the area of the triangle formed by joining O to c3 and b4 . Thus total torque is 2tA by summation. 8.4.1 STIFF-JOINTED FRAMES Where structural members are curved or cranked over wheel arches or drive shaft tunnels the unit load method of analysis applied to stiff-jointed frames is particularly useful Fig. 8.8. It is best understood by considering a small elastic element in a curved beam a which is otherwise assumed to be rigid. An imaginary load w at P is then considered to cause vertical displacement A the beam deflects under the influence of the bending moment and it can be shown that A f Mm EI. ds where m is bending moment due to imaginary unit load at P and M due to the real external load system. An example might be a .
