https://paginas.fe.up.pt/~iccs16/CD/721-760/735Belingardi_Boria_Obradovic.pdf

Lightweight design and crash analysis of composite frontal impact energy absorbing structures

Impact resistance and damage tolerance of fiber reinforced composites: A review

Experimental study on crashworthiness of empty/aluminum foam/honeycomb-filled CFRP tubes

Lightweight design of carbon twill weave fabric composite body structure for electric vehicle

Design optimization and manufacture of hybrid glass/carbon fiber reinforced composite bumper beam for automobile vehicle

Composite have been increasingly used in cars for their advantages of lightweight, high strength, corrosion resistance and easy manufacturing. Recently, carbon fiber reinforced plastic (CFRP) gains growing popularity in numerous advanced and high performance applications for crashworthiness thanks to its superior impact resistance, respect to metals or other composite materials. Maximising impact protection of carbon fibre reinforced plastic laminated composite structures, predicting and preventing the negative effects of impact on passengers are paramount design criteria for ground vehicles. In this paper the impact modelling of a frontal impact attenuator for a specific racing car will be investigated. The current work is based on the application of an explicit nonlinear finite element code, such as LS-DYNA, and on the experimental verification of the results, by means of an appropriately instrumented drop weight test machine. The thin-walled layered structure was numerically analysed using both shell and solid elements in order to reproduce the laminate as closely as possible, taking into account also the possibility during crushing of an interlaminar failure which plays a significant role during energy absorption mechanism. The proposed models are able to predict, with a good level of accuracy, the deformation process of such impact attenuator when subjected to dynamic loading as those imposed by technical regulation.

Composite impact attenuator with shell and solid modeling

Topology Optimization (TO) represents a relevant tool in the design of mechanical structures and, as such, it is currently used in many industrial applications. However, many TO optimization techniques are still questionable when applied to crashworthiness optimization problems due to their complexity and lack of gradient information. The aim of this work is to describe the Hybrid Kriging-assisted Level Set Method (HKG-LSM) and test its performance in the optimization of mechanical structures consisting of ensembles of beams subjected to both static and dynamic loads. The algorithm adopts a low-dimensional parametrization introduced by the Evolutionary Level Set Method (EA-LSM) for structural Topology Optimization and couples the Efficient Global Optimization (EGO) and the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) to converge towards the optimum within a fixed budget of evaluations. It takes advantage of the explorative capabilities of EGO ensuring a fast convergence at the beginning of the optimization procedure, as well as the flexibility and robustness of CMA-ES to exploit promising regions of the search space Precisely, HKG-LSM first uses the Kriging-based method for Level Set Topology Optimization (KG-LSM) and afterwards switches to the EA-LSM using CMA-ES, whose parameters are initialized based on the previous model. Within the research, a minimum compliance cantilever beam test case is used to validate the presented strategy at different dimensionalities, up to 15 variables. The method is then applied to a 15-variables 2D crash test case, consisting of a cylindrical pole impact on a rectangular beam fixed at both ends. Results show that HKG-LSM performs well in terms of convergence speed and hence represents a valuable option in real-world applications with limited computational resources.

Hybrid Strategy Coupling EGO and CMA-ES for Structural Topology Optimization in Statics and Crashworthiness

Quality check of induction motor (IM) is a crucial phase for manufacturers. Among the large number of tests usually applied at the end of the production line, the vibration analysis allows to identify mechanical failures such as damaged bearings or rotor faults. This study proposes an end-of-line quality control procedure based on vibrational analysis, in both radial and axial directions, to identify mechanically faulty IMs. Many features in time and frequency domains have been extracted from time experimentally recorded signals and frequency spectra, and a suitably selected set of them has been fed into four classification models based on Logistic Regression and k-NN techniques. Results are encouraging, and an accuracy higher than 94% is achieved by all classifiers. A more extensive experimental acquisition is planned in the near future to validate the obtained results.

Mechanical fault detection for induction motors based on vibration analysis: a case study

Composite impact attenuator with shell and solid modelling

Nowadays each manufacturers of racing cars must pass specific crash tests controlled by legislation, before seeing their vehicles in the market and in motor racing. In order to ensure the driver’s safety in case of high-speed crashes, special impact structures must be designed to absorb the race car’s kinetic energy and limit the decelerations acting on the human body. This target is achieved thanks to the synergy between the numerical and experimental analysis. Investigated in this work is the best solution, in terms of energy absorption, for a specific frontal impact attenuator in CFRP material with sandwich structure. In particular, given the geometry reported by the manufacturer, it has been necessary to find the right combination of material and lamination varying the stacking sequence and its disposition. Analyses have been conducted by the joining of numerical models, performed using LSDYNA, with experimental tests, through an instrumented drop tower equipment.

Simonetta Boria

Papers

Composite impact attenuator with shell and solid modeling

Hybrid Strategy Coupling EGO and CMA-ES for Structural Topology Optimization in Statics and Crashworthiness

Mechanical fault detection for induction motors based on vibration analysis: a case study

Composite impact attenuator with shell and solid modelling

Investigation of the most efficient solution for a specific vehicle impact attenuator in CFRP material