Abrasive waterjet (AWJ) cutting technology has been used extensively for the cutting and processing of almost all engineering materials because of its precise cutting technique and the lack of damage caused. Currently, the use of abrasive waterjet cutting in the natural stone industry is increasing. However, the effectiveness of abrasive waterjet cutting of natural stones is dependent on the rock properties and machine operating parameters. Consequently, this paper presents the influence of abrasive waterjet machining parameters on the surface texture quality of Carrara marble. The results have shown that the abrasive waterjet cutting process offers better cut surface texture quality of Carrara marble under certain parameter conditions as well as being more environmentally-friendly. The stand-off distance shows the opposite effect on both surface roughness and waviness. With a view to reducing the machining costs, every user tries to select the traverse rate of the cutting head to be as high as possible, but results show that increasing the traverse rate always causes a corresponding increase in terms of inaccuracy, surface roughness, R a ≈ 93.7 µm, and waviness, W a ≈ 92.6 µm. The abrasive mass flow rate is not a significant parameter during the cutting process. In all investigations, it was found that the machined surface of the marble is smoother near the jet entrance, R a ≈ 4 µm, and waviness, W a ≈ 5 µm, and increasingly becomes rougher towards the jet exit. The result also shows that the micro-hardness value of the Carrara marble was in the range of 122 HV to 124 HV.

Printed circuit boards constitute the basis of most electronic devices and are mainly fabricated of thin copper films bounded to fiber epoxy laminates, such as FR4. Vibrational stress can induce device failure, and hence, studies addressing their modal properties have important applications. In this paper, cantilever samples made of bare copper bounded to FR4 have been studied to analyze, for the first time, the vibration behavior of specimens with different aspect ratios, with and without central holes of different diameters. Natural frequencies and damping ratios were determined experimentally and analytically using a finite element method for four groups of samples with a very good correspondence between both methods. The fundamental resonance frequency of all the specimens was found to be less than 40 Hz and the influence of a central hole was not significant to affect the modal properties.

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Microelectromechanical systems (MEMS) are made of components in the range of 1 to 100 micrometers. These systems have a large application in electrical and electronic devices. The manufacturing of MEMS categorized under semiconductor device branch fabrication. The performance of such precision material very strongly depended on the mechanical and fracture properties of the composite material they get fabricated from. A MEMS thin strips are manufactured by bonding a thin copper film on a substrate of glass-reinforced laminated fabric with an epoxy resin binder. Generally, the tested samples are glass fiber laminates with a 1.5mm thickness having 35-micron copper layer. Two sets of samples were cut; first ones are in the form of a flat specimen with a small hole at the center for size effect tests whereas, the second ones are double edge notch (DENT) specimens for essential work of fracture tests. The fracture toughness of such material is measured using essential work of fracture tests. These types of material are considered a quasi-brittle material which mainly anisotropic material, therefore, the size effect is tested over this material. The results showed that the essential work of fracture for this MEMS material is measured as 72.883 / 2 and is subject to size effect which make a reduction in nominal strength namely 15%.