Recycling waste tires being important for both economical and environmental reasons, ground tire rubber can be blended with other polymers, modifying their properties. In order to characterize and explain these modifications, an experimental study was carried out concerning the improvement in the dynamic damping properties when adding recycled ground tire rubber (GTR) fillers to an elastomeric matrix (ethylene vinyl acetate, EVA).To evaluate the influence of both the GTR and the porosity in a GTR/ EVA composite, three samples have been elaborated by injection:the EVA matrix alone, a GTR/EVA composite, and a GTR/EVA porous composite. Dynamic measurements of the samples were performed using dynamic mechanical thermal analysis. The Young’s modulus and loss factor of these materials are estimated using the frequency—temperature equivalence introduced by Williams—Landel—Ferry expanding the measurement of the dynamic properties over a wider range of frequencies. This method showed that in low-frequency bandwidth, the loss factor has been improved by the addition of GTR to the EVA matrix. The α-relaxation study showed lower activation energy for both the GTR-filled composites leading to the conclusion that the mobility of the polymer chains has been improved by addition of GTR. The impact behavior study carried out using a weight drop test experiment also concluded to better impact energy absorption for the GTR-filled composites at the expense of a larger maximum displacement.

The use of composite materials undergoes a significant growth in many industries including aeronautic, railway, and automotive. Laminated composites are often subjected to severe loading conditions such as hailstones on aircraft and road gravels on automobiles. The present paper deals with the damage tolerance in carbon fiber-reinforced polymer structures caused by low velocity multiple impacts. Low velocity multi-impact tests at different energy levels (10, 15, and 20 J) are performed in order to simulate the gravels' impact conditions corresponding to mass of 10–50 g for velocity of 100–150 km/h. These tests were carried out on composite laminates with three types of stacking sequences (AERO, QIQH45, and QIQH60). AERO, widely used in aviation industry, is symmetric stacking sequence, and the two others QIQH45 and QIQH60 are quasi-isotropic and quasi-homogeneous laminates based on 45° and 60° ply orientation, respectively. Two specific parameters D and d are deduced from force–displacement and force–time responses which make it possible to rank the three stacking sequences to their damage tolerances. The impact damage assessment within the composite material with non-destructive testing method using ultrasonic inspection gives a good correlation with parameter D. Better impact damage tolerance is achieved with QIQH45 than the QIQH60 and AERO laminates. The parameter D can be regarded as a failure criterion for dimensioning of composite structures subjected to repetitive impacts.

The aim in this paper is first and foremost to present an experimental method for measuring the dynamic characteristics of granular rubber. Dynamic measurements on recycled granular rubbers are performed here using dynamic mechanical thermal analysis. The Young’s modulus and loss factor of these materials are estimated by using the frequency—temperature equivalence introduced by Williams—Landel—Ferry. It allows us to describe the dynamic properties over a wide range of frequencies. An increase in the wave speed and a decrease in the loss factor were observed with an increase in the frequency for ground tire rubber (GTR) and compound particles obtained by extrusion of GTR—ethylene vinyl acetate blend. However, for recycled polyurethane particles, the loss factor increases with increasing frequency. Then, we investigate the damping efficiency of granular rubbers introduced into a metallic tube, which was subjected to vibrating bending loads. A numerical model is presented to predict the frequency response for the displacement—force function of the tube—particles system. Model prediction is hence validated through a comparison with experimental results. Second, this paper also aims at calculating the optimum weight of granular material with maximum allowable damping effects on tube subjected to bending vibrations. For this purpose, a technique is proposed from the model developed by optimizing the apparent mass of granular material and the dissipation energy of the tube—particles system. Optimization is achieved by a nondominated storing genetic algorithm (NSAG-II). From the results, this technique can be successfully used to optimize the frequency dependence of wave speed and the loss factor of granular rubber with optimized weight.