J. Babu

Assessment of delamination in composite materials: A review:

The perennial challenge for the industry is to make parts, assemblies and machinery lighter and more efficient. This has led to progressively wider application of composites due to their excellent strength, stiffness and corrosion resistance properties. Composite components are assembled predominantly by fastening, which makes drilling a common machining process for such components. Delamination of the component surface at entry and exit of the drill is a drilling defect frequently encountered. Assessment of the severity of the delamination is necessary for correction and improvement of the performance of the parts and assemblies. Over a period of time, several factors have been suggested as the index of delamination for comparison and control. Also, various techniques are being adopted to measure the extent and severity of delamination so as to calculate the assessment factor. This study aims to present and review the different means and methods for the assessment of delamination.

Development of a comprehensive delamination assessment factor and its evaluation with high-speed drilling of composite laminates using a twist drill

Composites are cutting edge engineering materials for modern high-technology products. Their heterogeneous structure entails processing defects uncommon with metallic parts. Drilling is a crucial manufacturing process to facilitate fastening and assembly of composite components. High-speed drilling especially is a promising technique to increase the productivity as well as the quality of the drilled hole. The severity of delamination damage around the drilled hole is a critical factor in the error-free performance of these parts in service. A new method to characterize the delamination induced by drilling with a comprehensive assessment factor called effective equivalent delamination factor is developed to overcome the limitations of other measures being used hitherto. The capability and appropriateness of effective equivalent delamination factor as a delamination assessment factor are verified from experimental results.

Application of the grey-based fuzzy logic approach for materials selection

Abstract Material selection is considered an important step in the design and manufacturing of a part/product. Wrong selection of material may cause poor quality, increase in cost, early failure of the product, or any combination of them. It may also create difficulties in the manufacturing process leading to increases in manufacturing time and cost. The general rule in design is to select materials based on their properties that match with the product requirements. Hence, decision making for material selection is a crucial process, and several mathematical tools and techniques have been presented in the literature to aid this process. Those techniques have their own advantages and limitations. This paper proposes the application of the grey-based fuzzy logic approach to solve three real time material selection problems. For all the examples, the first and the last ranks of materials derived using the adopted method and those obtained by past researchers are exactly the same. This indicates that when uncertainties are involved, grey-based fuzzy logic can be employed as an efficient tool for solving complex material selection problems.