ELASTIC STRESS ANALYSIS OF THREADED CONNECTIONS

Abstract

"ELASTIC STRESS ANALYSIS OF THR.&DIJD CONNECTIONS" Ordinarily, the design of threaded connection is based of finding the bolt diameter on the basis of nominal stress in the core and the length of thread engagement on the basis of shear area, How-ever it has been observed that the failure of threads in a ductile material is due to high tensile fillet stresses caused by bending of the threads. Pence, determination of these fillet stresses should serve as a part of the basis for the design of threaded connections. Solution of this problem is done in two phases; first the load distribution from thread to thread is determined and then maximum tensile stress in the most severely loaded thread is evaluated. Two ways are suggested for the solution of the first phase: i) Set of simultaneous equations which are convenient for joints having large number of engaged threads and ii} An electrical simulator, which has been designed on the basis of the above equations, forms an easy tool for more general use. Effect of following parameters on the load distribution has been studied by the electrical simulator on a ten threaded connection : a) Nut Body Stiffness; b) Bolt 3dy Stiffness c) Thread Stiffness. xv For the second phase of evaluation of the fillet stress,. - two methods have been suggested i) Photoelastic testing ii) An empirical formula given by ='r. Heywood. Photoelastic testing has been used for a comparative study on the performance of following thread profiles : a) %Vhittorth. b) American Standard. c) British Association. d) Unified Indian Standard. In closing mention is made of -typical considerations that should aid in the design of effecient threaded connection. M:0_ 5