In this study, laser surface treatment of CFRP made of PPS thermoplastic matrix by means of Q-switched Yb:YAG fiber laser is investigated with the aim to improve CFRP adhesive bonding. Two set of experimental tests were developed. In the first, laser treatments were executed fixing the average power (Pa) and changing: the pulse power, the scanning speed, the hatch distance, and the scanning strategy. These tests were performed to individuate the laser-material interaction mechanisms and the process window. The treated surfaces were investigated using optical microscopy. It was found that the treatment is able to remove the outer layer of the matrix up to the exposure of underlying reinforcement. However, depending to the released energy, incomplete cleaning or excessive damage may occur. Then, the operating window was experimentally determined. In the second experimental tests, single lap shear tests were performed on samples treated under the most promising process conditions, to verify the laser treatment effectiveness. It was found that the laser treatment, compared to the untreated samples, is able to increase the apparent shear strength up to three times

The present article is concerned with the production of cross-linked low-density polyethylene. The aim is to gain information about costs/ benefits of two cross-linking methods, which are the chemical through silane grafting and the electron-beam irradiation. These two methods ORDER REPRINTSwere used at the Megarad firm (Italy) for cross-linking of low-density polyethylene, which was mainly used for electric cable insulation. The two cross-linking processes were examined by evaluating the performance of the end product and the production costs. The performance of the final product was assessed through experimental tests, which consisted in the evaluation of some peculiar properties of the material such as gel fraction, thermal modifications under heat fluxes, modulus of elasticity at 150 C, elongation parameters. Costs were analyzed by considering both direct and indirect costs. It seems that, notwithstanding the elevated costs of installation, the electronbeam irradiation method is preferable because it allows for a product of superior characteristics with the lowest production costs.

In a previous paper, the authors dealt with the current showstoppers that inhibit commercial applicability of morphing systems. In this work, the authors express a critical vision of the current status of the proposed architectures and the needs that should be accomplished to make them viable for installation onboard of commercial aircraft. The distinction is essential because military and civil issues and necessities are very different, and both the solutions and difficulties to be overcome are widely diverse. Yet, still remaining in the civil segment, there can be other differences, depending on the size of the aircraft, from large jets to commuters or general aviation, which are classifiable in tourism, acrobatic, ultralight, and so on, each with their own peculiarities. Therefore, the paper aims to trace a common technology denominator, if possible, and envisage a future perspective of actual applications.

No abstract

No abstract