Mechanical Design Handbook

In a design situation, the expected load on a column would be known, along with the length required by the application. The designer would then specify the following: 1. The manner of attaching the ends to the structure that affects the end fixity. 2. The general shape of the column cross section (for example, round, square, rectangular, and hollow tube). 3. The material for the column. 4. The design factor, considering the application. 5. The final dimensions for the column. It may be desirable to propose and analyze several different designs to approach an optimum for the application, so software such as this facilitates the process. It is assumed that the designer for any given trial specifies items 1 through 4. For some simple shapes, such as the solid round or square section, the final dimensions are computed from the appropriate formula: the Euler formula , or the J. B. Johnson formula. If an algebraic solution is not possible, iteration can be done. In a design situat

Reactions are the forces and/or couples acting at the supports and holding the beam and holding the beam in place. In some cases the user should enter a distributed load to account for the weight of the beam. The shear V effective on a section is the algebraic sum of all forces acting parallel to and on one side of the section, The bending moment is the algebraic sum of the moments due to applied loads and other applied moments to one side of the section of interest. Using value V bending moment can be calculated where x = position on the beam measured along its length M 0 = constant of integration evaluated from the boundary conditions. A bending moment that bends a beam convex downward (tensile stress on bottom fiber) is considered positive, while convex upward (compressive on bottom fiber) is negative. Moment and shear diagram constructed by plotting to scale the particular entity as the ordinate for each section of the beam. Such diagrams show in continuous form the variation am

A set of n bolts is to be used to provide a clamping force of F between two components. The load is shared equally among the bolts. Specify suitable bolts, including the grade of the material, if each is to be stressed to K % of its proof strength. The variable K is called the demand factor. The load on each screw is to be P = F /n Specify a bolt made from an SAE grade steel, having a proof strength s psi. Then the allowable stress is s a = K.[ s ] The required tensile stress area for the bolt is then A t = P / s a From a table find the required tensile stress area for the thread. The required tightening torque will be T = k1 x D x P where D - nominal outside diameter of threads P - clamping load k1- constant dependent on the lubrication present Constant dependent on the lubrication present For average commercial conditions, use k1 = 0.15 if any lubrication at all is present. Even cutting fluids or other residual deposits on the threads will produce conditions