Investigating Effects of Imperfections on Aluminum Stepladder Using Finite Element Analysis

Abstract

Ladders are a valuable tool, but they can also be dangerous. In 2020, ladder-related falls resulted in more than 100 fatalities and thousands of injuries, particularly in the installation, maintenance, and repair industries [1]. The ANSI A14.2 standard governs the safe construction, design, testing, and use of portable metal ladders, outlining requirements for ladder rung spacing, connections, and angle of inclination. While 15 different load tests are performed to ensure a ladder meets the standard, it’s important to note that these tests use statistical tolerances and represent pass/fail criteria. Altering the cross-section of a shape can impact its stiffness, and imperfections can affect a structure’s collapse. Understanding the testing limitations is crucial. To reduce ladder-related injuries and fatalities, imperfection-sensitive ladders can be detected, evaluated, and identified using 3D modeling and nonlinear finite element analysis (FEA). This paper presents a technique for using linear-elastic buckling analysis to identify potential failure modes. It is followed by nonlinear static analysis with material plasticity to detect significant decreases in strength when dents or other imperfections are included in the geometry or when the applied load directions are changed.