Giangiacomo Minak

Effect of PVDF nanofibers on the fracture behavior of composite laminates for high-speed woodworking machines

The use of light composites when designing fast moving parts for machine tools is emerging as a very efficient solution for improving productivity. Nevertheless, several aspects of these materials have to be carefully considered in woodworking. This paper aims to investigate the effect of interleaved nanofiber on mode I interlaminar properties and the failure modes that occur in this mode. For this purpose, woven carbon/epoxy laminates with and without Polyvinylidene difluoride nanofibers in the mid-plane were subjected to mode I interlaminar loading and the results were compared with each other. Acoustic emission technique was also utilized for better understanding of the failure modes that occurred in the virgin and nanofibers-modified specimens. Mechanical data and acoustic emission parameters associated with pattern recognition analyses were used for investigation of the interlaminar properties and the occurred failure modes. The mechanical results showed that the electrospun nanofibrous mat was able to increase the GIC by 98%. The acoustic emission results highlighted that different failure modes were the origin of different interlaminar failure behaviors. Different percentages of the failure modes in the modified specimens compared with the virgin ones were observed. Furthermore, the number of occurred interlaminar failure modes diminished in the modified composite layers.

A Brief Review on Determinant Aspects in Energy Efficient Solar Car Design and Manufacturing

In the past decades, sustainable means of transportation have become an important issue once they are potentially able to supply modern transport needs whilst not harming the environment. Accordingly to this general interest, solar vehicles have been developed by several institutions worldwide to participate in international class races, promoting this research field. As the competitiveness increased, solar technologies evolved toward noteworthy solutions for a modern and sustainable mobility. Hence, this work intends to provide a general overview on solar vehicles, particularly regarding the main design and manufacturing features that allowed to increase energy efficiency, considering the relevance of this factor for solar cars. Due to the huge amount of information available, a limited number of aspects was selected for further analysis, mainly related to design and engineering, such as: weight reduction, aerodynamics and kinematics, mechanics and advanced materials.

Damage evaluation of laminated composites under low-velocity impact tests using acoustic emission method

The main goal of this investigation is to characterize the damage in laminated composites under low-velocity impact tests using a new cost-effective approach. To this aim, a quasi-static test was first carried out to obtain initial information about impact tests. Low-velocity impact tests were then applied in unidirectional glass/epoxy composite specimens, and acoustic emission signals were captured during impact events. Next, acoustic emission signals were analyzed using wavelet approach to distinguish released energy related to each distinct damage mechanism. Besides, an approach was provided to estimate threshold impact energy from the quasi-static test, beyond which damage significantly extends. As a final point, the acoustic emission-based procedure using wavelet transform method was proposed to predict the total damage area. Finally, it was found that this acoustic emission methodology can be a capable approach in damage characterization under impact loads in composite structures.

Determination of stress distribution in women’s shoes during high-heeled gait

This work is aimed at investigating loads, strains and stresses emerging in a pair of women’s fashion shoes during high-heeled walking with the general objective to improve the footwear safety. In particular, the resistance of an 11-centimetre heel in women’s shoes was evaluated by experiments under the most common conditions of use (e.g. walking, standing, sitting on a car, getting up from a chair, going downstairs and upstairs, jumping). The heel was substituted by a strain gage instrumented aluminium hollow cylinder with the capability of measuring the deformations in several critical points. These measures permitted to implement a complete time depending stress-strain analysis. Deformations were also related to forces and moments acting on shoes, experimentally deriving these actions for each condition of use. A comparison with stresses generated during standard tests was also performed.