Giovanni Belingardi

Vehicle Crashworthiness Design — General Principles and Potentialities of Composite Material Structures

Increasing demands from customers, government concern and national and international regulations put occupant safety at the forefront of vehicle design considerations. The safety level of a passenger vehicle, put in evidence by the number of stars (up to five stars) obtained in the European New Car Assessment Program (EuroNCAP) or in the US New Car Assessment Program (USNCAP) rating tests, are at present a very important point in the market promotion strategies for automotive manufacturers. The USNCAP is under mandate from the National Highway Traffic Safety Administration (NHTSA).

Surrogate modeling in the design optimization of structures with discontinuous responses with respect to the design variables - A new approach for crashworthiness design

Advances to computational technology have resulted in the reduction of computational effort for crashworthiness analysis, hence enabling structural design optimization. Surrogate modeling has been shown to further reduce computational effort as well as to smooth noisy responses. Crashworthiness optimization problems are, though, ill posed as they include nonlinear, noncontinuous and noisy responses. This violates the Hadamard conditions for well-posed problems and therefore the applicability of gradient-based algorithms is limited.

Thermoplastic Adhesive for Automotive Applications

The objective of this study is to give a general overview on the thermoplastic adhesives used in the automotive sector. Some of the main applications in which the hot-melt adhesives (HMAs) are used in automotive industries are indicated, together with the adhesive characteristics that explain the reasons for their adoption. The chemical and mechanical behavior of these adhesives and the generally used experimental characterization methods are presented and opportunely criticized. In this study, some of the main properties of thermoplastic adhesives are reviewed together with the standard tests used for their characterization. For what concerns the structural performance, single lap joint test is used to determine the shear strength of the adhesive joint. Thermogravimetric analysis and Fourier transform infrared spectroscopy are used to characterize the chemical properties of the adhesive. This study clarifies what are the potentialities of a thermoplastic adhesive in car industries compared to other adhesives.

Vacuum infusion of a composite E-glass vinylester laminate for nautical application: experimental response to repeated impacts.

The aim of this paper is to investigate the response to repeated impacts of a non-symmetric glass fibre reinforced laminate. The laminate is intended for a nautical application and the manufacturing technique is vacuum infusion. In a first part of the work, four impact velocities (1.566 m/s, 2.215 m/s, 3.132 m/s and 3.836 m/s) were considered, and a minimum of four specimens for any given velocity were subjected to forty repeated impacts or up to perforation. The impact response was evaluated in terms of damage progression by visual observation of the impacted specimens, evolution of the peak force and of the bending stiffness with the number of impacts and by calculating the damage degree (ratio between the absorbed energy and the impact energy). In a second part of the work, additional single impact tests were performed at 4.429 m/s and 6.264 m/s to investigate the laminate strain-rate sensitivity. Repeated impact tests pointed out that the delamination area grows very rapidly in the first few impacts to then level off, following closely the behaviour of the bending stiffness against the number of impacts. The value of the peak force increases in the first few impacts due to compaction and strain-hardening of the resin with a related decrease of the damage degree. Comparison between quasi-static penetration tests and impact tests demonstrates a strain-rate dependency of the laminate bending stiffness and first damage load. The values of R-2 show a good fitness of a linear function on the experimental data.

Traumatic events in human head: biomechanical insight by means of a finite element model

Head injuries due to traumatic events in case of head impact are one of the main causes of death or permanent invalidity in vehicle crash. The main purpose of the present work is to evaluate pressure and stress distributions in bones and brain tissues of a human head due to an impact by means of numerical simulations. Pressures and stresses in the different zones of the head can be related to the main brain injuries as verified by head traumatology doctors. The availability of a numerical model of head allows to quantify the relationship between type and intensity of the impact and the possible head injury. This capability represents a relevant step torward an effective traumatic injury prevention. The proposed numerical model is quite complex although some simplifications have been introduced like modeling all the inner organs as a continuum without sliding interfaces or fluid elements. Geometrical characteristics for the finite element model have been extracted from CT (Computer Tomography) and MRI (Magnetic Resonance Image) scanner images, while material mechanical characteristics have been taken from literature. The model has been validated by comparing the numerical results and the experimental results from literature. The protecting action of the ventricles and of several membranes (dura mater, tentorium and falx) has been evaluated.© 2006 ASME