Cruisers are multi-occupant solar vehicles that are conceived to compete in long-range (over 3,000 km) solar races based on the best compromise between the energy consumption and the payload. They must comply to the race's rules regarding the overall dimensions, the solar panel size, functionality, and safety and structural requirements, while the shape, the materials, the powertrain, and the mechanics are considered at the discretion of the designer. In this work, the most relevant aspects of the structural design process of a full-carbon fiberreinforced plastic solar vehicle are detailed. In particular, the protocols used for the design of the lamination sequence of the chassis, the leaf springs structural analysis, and the crash test numerical simulation of the vehicle, including the safety cage, are described. The complexity of the design methodology of fiber-reinforced composite structures is compensated by the possibility of tailoring their mechanical characteristics and optimizing the overall weight of the car. Video LinkThe video component of this article can be found at https://www.jove.com/video/58525/ A new design philosophy must be approached, including a different vision of material use and manufacturing. First, materials must be selected based on the highest strength-to-weight ratio and, as a direct consequence, carbon-reinforced fiber plastics represent an optimal solution. Furthermore, specific stratagems in the design must be implemented.In the present article, the procedures employed to design some of the most important structural parts of the solar vehicle, such as its monocoque chassis, the suspension, and even a computational crash test are depicted. The final scope is to obtain rapidly a solar vehicle with the least possible weight, in a trade-off with aerodynamics and race rules.

Applications of Carbon Fibre Reinforced Polymers (CFRP) at temperatures over 150–200 °C are becoming common in aerospace and automotive applications. Exposure of CFRP to these temperatures can lead to permanent changes in their mechanical properties. In this work, we investigated the effect of thermal ageing in air on the strength of carbon fabric/epoxy composites. To this end, accelerated artificial ageing at different temperatures was performed on carbon fabric/epoxy specimens. The flexural and interlaminar shear strengths of the aged specimens were assessed by three-point bending and short beam shear tests, respectively, and compared to those of unaged samples. For ageing at temperatures below the glass transition temperature of the resin, Tg, a moderate reduction of strength was found, with a maximum decrease of 25% for 2160 h at 75% Tg. On the other hand, a rapid strength decrease was observed for ageing temperatures above Tg. This was attributed to degradation of the epoxy matrix and of the fibre/epoxy interface. In particular, a 30% strength decrease was found for less than 6 h at 145% Tg. Therefore, it was concluded that even a short exposure to operating temperatures above Tg could substantially impair the load-carrying capability of CFRP components.

The effect of bond-line thickness on fatigue crack growth rate in adhesively bonded joints Pascoe, J. A.; Zavatta, N.; Troiani, E.; Alderliesten, R. C. A B S T R A C TThe effect of adhesive thickness on fatigue crack growth in an epoxy film adhesive (FM94) was investigated, using a combination of experiments and numerical modelling. For the range of thicknesses investigated an increased thickness led to an increased crack growth rate. It was found that the energy required per unit of crack growth did not depend on the adhesive thickness. In contrast, the energy available for crack growth does depend on the adhesive thickness.The numerical analysis confirms that the energy required per unit crack growth is not sensitive to the adhesive thickness, but that the plastic energy dissipation increases with the thickness. The experimental results imply that this increase of plasticity has an anti-shielding effect, as the crack growth rate is increased. IntroductionCompared to mechanical fastening, adhesive bonding offers the promise of lower weight structural joints. This is achieved by creating a smoother load transfer and removing the need for holes, and thus stress concentrations. Consequently adhesive bonding is an attractive option for structural designs in mass-critical applications, such as aerospace and automotive.Before adhesive bonding can be applied on a wide scale however, more understanding is needed of its fatigue crack growth (FCG) behaviour. Many prediction methods have been proposed in the past, but these are all based on empirical correlations rather than an understanding of the physics [1]. Pascoe et al. [2,3] and Alderliesten [4] have suggested that more insight into the underlying physics can be gained by measuring the dissipation of strain energy during the crack growth process. They showed that correlating the crack growth rate to the measured strain energy dissipation per cycle ( U N d /d ), rather than to the strain energy release rate (SERR), could account for most of the effect of the stress ratio (R).A small stress ratio effect was still observed. It was suggested that this might be caused by non-linearity of the force-displacement curve [3]. However further examination has shown that the force-displacement curve remains linear throughout the fatigue test [5]. An alternative hypothesis is that the observed difference in energy dissipation at different stress ratios, for a given crack growth rate, is caused by differences in the stress state and amount of plasticity at the crack tip. It is known from previous work that adhesive thickness affects these parameters [6][7][8][9][10], and thereby the fracture toughness.While various studies on the effect of layer thickness on fatigue crack growth have been published [11][12][13][14][15][16][17][18][19][20], identifying that thickness can have an effect, the reported results are not consistent. Furthermore there has been little effort to understand the mechanisms that cause adhesive thickness to affect the fatigue crack growth rate.

Resin transfer molding (RTM) technologies are widely used in automotive, marine, and aerospace applications. The need to evaluate the impact of design and production critical choices, also in terms of final costs, leads to the wider use of numerical simulation in the preliminary phase of component development. The main issue for accurate RTM analysis is the reliable characterization of the involved materials. The aim of this paper is to present a validated methodology for material characterization to be implemented and introduce data elaboration in the ESI PAM-RTM software. Experimental campaigns for reinforcement permeabilities and resin viscosity measurement are presented and discussed. Finally, the obtained data are implemented in the software and then compared to experimental results in order to validate the described methodology.

Laser shock peening has established itself as an effective surface treatment to enhance the fatigue properties of metallic materials. Although a number of works have dealt with the formation of residual stresses, and their consequent effects on the fatigue behavior, the influence of material geometry on the peening process has not been widely addressed. In this paper, Laser Peening without Coating (LPwC) is applied at the surface of a notch in specimens made of a 6082-T6 aluminum alloy. The treated specimens are tested by three-point bending fatigue tests, and their fatigue life is compared to that of untreated samples with an identical geometry. The fatigue life of the treated specimens is found to be 1.7 to 3.3 times longer. Brinell hardness measurements evidence an increase in the surface hardness of about 50%, following the treatment. The material response to peening is modelled by a finite element model, and the compressive residual stresses are computed accordingly. Stresses as high as −210 MPa are present at the notch. The ratio between the notch curvature and the laser spot radius is proposed as a parameter to evaluate the influence of the notch.