An Elastica Arm Scale

TL;DR

This paper introduces a novel deformable arm scale based on nonlinear rod mechanics, validated experimentally, which measures loads through elastic deflections, with potential applications in various fields like robotics and plumbing.

Contribution

It presents the concept, theoretical analysis, and experimental validation of a deformable scale using elastic rods, a significant departure from traditional rigid scales.

Findings

High accuracy in load measurement within certain ranges

Unique equilibrium configurations achieved with elastic arms

Relevance to snaking behavior in confined beams

Abstract

The concept of 'deformable arm scale' (completely different from a traditional rigid arm balance) is theoretically introduced and experimentally validated. The idea is not intuitive, but is the result of nonlinear equilibrium kinematics of rods inducing configurational forces, so that deflection of the arms becomes necessary for the equilibrium, which would be impossible for a rigid system. In particular, the rigid arms of usual scales are replaced by a flexible elastic lamina, free of sliding in a frictionless and inclined sliding sleeve, which can reach a unique equilibrium configuration when two vertical dead loads are applied. Prototypes realized to demonstrate the feasibility of the system show a high accuracy in the measure of load within a certain range of use. It is finally shown that the presented results are strongly related to snaking of confined beams, with implications on locomotion of serpents, plumbing, and smart oil drilling.