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This paper presents a simplified numerical simulation tool for the elasto-plastic calculation of plane articulated truss by the finite element method (FEM) in MATLAB. The simplified approach consists of linearizing isotropic strain-hardening (to obtain a bilinear material law). The numerical implementation is built on the basis of the incremental and iterative FEM algorithms. The numerical resolution technique used is based on the projection methods of the modified Newton-Raphson solution. The MATLAB program is developed for the application of a 3-bar truss under monotonous quasi-static loading. Different values of the approximation error of the convergence criterion are used to study its impact on the quality of the algorithm. Numerical simulations have shown the reliability and quality of our simplified approach regardless of the approximation error.

This paper presents a approach to determining the level of damage on rigid PVC pipes (polyvinyl chloride), destined for the supply of drinking water, and previously subjected to quasi-static impact. The originality of the work has been to experimentally characterize the level of damage via readily measurable physical quantities obtained under operating conditions. For this purpose, a wide range of experiments were performed. Firstly, trials involving impact with a hemispherical-end hammer weighing 16kg, dropped from a height of between 0 -2m on portions of rigid PVC pipe. Thereafter, the dimensions of the affected area on the portions of the pipe are measured using a Tridimensional Measuring Machine (TMM). Finally, tensile tests on flat test pieces from around the impacted area of the pipe section were used to determine the postimpact residual mechanical strength. This investigation on post-impact properties allows the definition of the level of damage reached via the unified theory model of Bui Quoc. By analogy to the latter, the damage is expressed as a function of the area of the impacted section.