G. Minak

Wavelet-based acoustic emission characterization of residual strength of drilled composite materials

Drilling composite materials is one of the secondary processes of manufacturing industrial structures. However, drilling composite materials presents a number of problems such as degradation of mechanical behavior. In this study, effects of spindle speed, feed rate, and drill point geometry on residual tensile strength are studied. Acoustic emission technique with a wavelet-based signal processing method is developed to monitor the residual tensile strength of drilled laminates. Cumulative count, amplitude, and energy are used as time-domain parameters to characterize the process. According to wavelet analysis, frequency distribution and energy percentage of each damage mechanism (matrix cracking, fiber breakage, and fiber slipping) during tensile test are determined.

Application of rapid tooling for the production of moulds suitable for autoclave forming of CFRP

Purpose – The purpose of this paper is to demonstrate the applicability of an indirect rapid tooling technique to the autoclave forming of carbon fibre reinforced plastic laminates.Design/methodology/approach – A rapid prototyping machine was used to process a photo elastic resin to fabricate the pre‐moulds. Liquid particle‐filled epoxy resin was poured in the pre‐mould and cured in an oven. Real autoclave process conditions were then applied to the mould several times to assess the geometrical stability and the accuracy of the produced parts, measured using a laser 3D scanner.Findings – This paper reports the procedures developed for the rapid manufacture of carbon fibre reinforced plastic components.Research limitations/implications – The method is applicable to components of small to medium dimensions (max 500u2009mm).Originality/value – This is a pioneer attempt towards the rapid manufacturing of high performances composite components. It has been presented for patenting purposes (Gian Luca Monti, Ezequie...