Materials study on a Telescopic Barbell design using Finite Element Model

Abstract

Abstract A telescopic barbell design is proposed, and its design is optimized by evaluating numerous scenarios based on geometry and materials, using COSMOSWorks® (now Solidworks Simulation®). The product is intended for general purpose strength training use and is designed to cater to the portability limitations of existing barbels, which are bulky and lengthy. The objective of this design study is to minimize the cost of manufacturing, by selecting a suitable economical material, provided the maximum deflection (stiffness criteria) and yield stress (strength criteria) is within the design constraints. The decision is not obvious, when strength, stiffness and cost criteria is to be met since high strength materials will weigh less (for the same load) but will cost more and vice versa. Hence, parametric design simulations must be done to choose the most optimum design, which meets the design constraints. Materials from three different steel categories (mild steel, stainless steel, and high strength steel) are selected and a total of 441 scenarios (147 per material) are simulated by parametric geometry alterations. The most economical design, which satisfies both strength and stiffness criteria, is selected and is further analyzed for contact stresses, to ensure these relatively high stresses do not penetrate deep inside the body. It is concluded in this study, with sufficient evidence, that A-36 (mild steel) is still the most economical material for this design, although it has the lowest yield strength, of the materials simulated. This is because the design should also satisfy the stiffness criteria and the Young’s Modulus for all the three grades of steel is very close. It is also concluded that design of barbells can be done based on global maximum stress values, rather than localized contact stresses, because edge/line contact is only present in the software environment, not in the physical service conditions.