Journal of the Association of Engineers, India

Sushanta Ghuku ¹, Kashi Nath Saha ¹

Affiliations
1 Mechanical Engineering Department, Jadavpur University, Kolkata-700032, IN

Abstract

Leaf spring is the simplest type of suspension spring commonly used in wheeled vehicles and its main cause of failure is large bending under load. Leaf spring is generally designed by modeling it either as curved cantilever beam with tip concentrated load or curved beam under three point bending. In spite of the widespread theoretical static analysis of leaf spring, there is lack of experimental fidelity in the ensuing models. Moreover, there is insufficiency in modeling the roller supports at eye ends and in addition, asymmetry in master leaf geometry and presence of drill hole in master leaf have not been considered properly. This paper presents design development and performance analysis of two different leaf spring testing rigs. The design considerations, detail descriptions of the components along with their manufacturing details are furnished here. The first set-up is a general purpose set-up for clamping structures, which models leaf spring as curved cantilever beam under tip concentrated load by considering only its one half. Experiment is carried out in this set-up to obtain deflection profiles of master leaf spring using image processing technique. Comparisons with theoretical results identify several insufficiencies in the present experimental model such as unknown clamping force, non-consideration of asymmetry in master leaf geometry and inappropriate modeling of support arrangement at eye ends. To overcome such insufficiencies, the second set-up is designed which simulates three point bending test. This set-up introduces roller supports at eye ends and considers asymmetry in the master leaf geometry. In both the cases, deflection profile is obtained using image processing technique and in the second set-up, strain gauge technique is adopted for strain measurement.

Keywords

Leaf Spring, Cantilever Beam, Three Point Bending, Experimental Work, Image Processing Technique, Strain Gauge Technique.

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Sushanta Ghuku ¹, Kashi Nath Saha ¹

Affiliations
1 Mechanical Engineering Department, Jadavpur University, Kolkata-700032, IN

Abstract

The present paper reports a review on several aspects associated with advancement in beam theories to predict size dependent mechanical behavior of micro and nano scale beam. Inherent geometric nonlinearity of large deflection couples with complicated material behavior of micro and nano sized beams, and makes such small scale beam problem very complicated. Hence, proper modeling of constitutive behavior and solution of nonlinear partial differential equation are the two major components in analysis of micro and nano beam. Developments in the two areas from classical to modern higher order approaches are critically reviewed in the paper. Several constitutive relations used to model material behavior of small scale beam and the frequently used analysis methods in association with computational solution schemes to solve nonlinear system governing equation are identified and presented in the paper. Increasing trend of using miniature devices and non-metallic materials leads towards several class of micro and nano beam problems according to application. The problems are not only limited to common beam problem like bending, vibration, static and dynamic stability, but also includes several interdisciplinary areas like fracture mechanics, bio-mechanics, molecular dynamics, material science, etc. Hence in addition to material modeling and analysis methods, type of problem encountered in literature and application areas together with experimental works on micro and nano sized beam like structures are also addressed in the review paper.

Keywords

Micro/Nano Beam, Size Dependent Deformation, Geometric Nonlinearity, Higher Order Continuum Mechanics, Constitutive Relation, Couple Stress Theory, Strain Gradient Theory, Nonlocal Theory.

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