# Nonlinear explicit analysis and study of the behaviour of a new ring-type brake energy dissipator by FEM and experimental comparison

J.J. del Coz Díaz, P.J. García Nieto, D. Castro-Fresno, J. Rodríguez-Hernández

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

## Abstract

The aim of this paper is to comprehensively analyse the performance of a new ring-type brake energy dissipator through the finite element method (FEM) (formulation and finite element approximation of contact in nonlinear mechanics) and experimental comparison. This new structural device is used as a system component in rockfall barriers and fences and it is composed of steel bearing ropes, bent pipes and aluminium compression sleeves. The bearing ropes are guided through pipes bent into double-loops and held by compression sleeves. These elements work as brake rings. In important events the brake rings contract and so dissipate residual energy out of the ring net, without damaging the ropes. The rope’s breaking load is not diminished by activation of the brake. The full understanding of this problem implies the simultaneous study of three nonlinearities: material nonlinearity (plastic behaviour) and failure criteria, large displacements (geometric nonlinearity) and friction-contact phenomena among brake ring components. The explicit dynamic analysis procedure is carried out by means of the implementation of an explicit integration rule together with the use of diagonal element mass matrices. The equations of motion for the brake ring are integrated using the explicit central difference integration rule. The presence of the contact phenomenon implies the existence of inequality constraints. The conditions for normal contact are and , where is the normal traction component and g is the gap function for the contact surface pair. To include frictional conditions, let us assume that Coulomb’s law of friction holds pointwise on the different contact surfaces, being the dynamic coefficient of friction. Next, we define the non-dimensional variable by means of the expression , where is the frictional resistance and t is the tangential traction component. In order to find the best brake performance, different dynamic friction coefficients corresponding to the pressures of the compression sleeves have been adopted and simulated numerically by FEM and then we have compared them with the results from full-scale experimental tests. Finally, the most important conclusions of this study are given.

Original language English 1571-1582 12 Applied Mathematics and Computation 216 5 6 Mar 2010 https://doi.org/10.1016/j.amc.2010.03.009 Published - 1 May 2010 Yes

### Bibliographical note

NOTICE: this is the author’s version of a work that was accepted for publication in Applied Mathematics and Computation. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Applied Mathematics and Computation, 216:5, (2010) DOI: 10.1016/j.amc.2010.03.009

## Keywords

• Inequality constraints
• Finite element analysis
• Explicit integration
• Elastoplastic material
• Coulomb’s law
• Contact analysis
• Weak solution

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