Comparison of Load Path Definitions in 2-D Continuum Structures

Abstract

The structural mechanics community has developed several methods to identify and visualize load paths in structures. There is no single accepted approach or method to characterize, quantify , visualize and tailor load paths. This paper compares various methods proposed to characterize and visualize load paths. The comparison is performed for a two dim ensional (2 -D) rectangular plate under plane stress conditions arising from different loading and boundary conditions. The effectiveness and computational effort of each method are compared . The comparisons shows the methods provide different results and i nsights into the load transfer mechanisms. No single method appears to emerge as a clear choice for characterizing load pat hs. However, some methods provide more qualitative and quantitative information on the trajectory and efficiency of load transfer alo ng load paths. I. Introduction Structural design engineers need to be able to visualize how a load is transferred from its application point to the support or reaction points . Knowing how load “flows” in a structure is important at the design stage to make s ure that the structure will perform its intended function properly. It is also important for optimum material utilization and for ass essing the overall integrity of a structure. In case the structure is damage d, it is crucial to anticipate how the load flo w will change in order to ensure that the structure can continue to perform it s basic functions. Thus , it is important to identify alternate load paths in case the primary load path is damaged. In addition to identifying alternate load paths, engineers may want to be able to specifically tailor alternate load paths so that the structure can perform its basic functions under various unforeseen damage conditions. Although it is clear why knowledge of load pathways is important , no unified approach has been de veloped to quantify, characterize, and visualize av ailable load paths in a structure . This work presents and compares different methods that have been developed for characte rizing load paths . . The methods are used to visualize load paths in a rectangular plate structure under various boundaries and loading conditions. The effectiveness of each method is investigated by analyzing the information obtained from each visualization. II. Load Path Definitions Over the years , the structural community has developed se veral methodologies that can be used to define load paths in a structure. Each method was derived differently and therefore result s in varied visualization s and interpretation s of structural load paths. The different methods investigated in this work are explained in the following sections. A. Using vectors aligned with directions of principal stresses