This paper presents an experimental and analytical study about the mechanical response at a different temperature on glass fiber-reinforced polymer laminates. The effect of different environmental conditions on compressive, tensile, stiffness, and viscoelastic behavior (storage modulus, loss modulus and damping ratio) of laminates were investigated. Before testing, laminates were preserved in a deep freezer at −80 °C, −20 °C, 0 °C, and room temperature (25 °C) for up to 60 days. Results confirmed that temperatures ranging from −80 to 50 °C, which were below the glass transition temperature of the epoxy resin, did not significantly affect the compressive, tensile, and stiffness performance of all laminates. When the testing temperature increased to 100 °C, the properties were decreased significantly due to the damaging of the fiber/matrix interface. Additionally, results obtained from dynamic mechanical analyses tests showed a drop-in storage modulus, high peaks in loss modulus and high damping factor at the glass transition region of the epoxy resin. The highest storage modulus, two phases of glassy states and highest damping ratio on the −80/G group of laminates were obtained. The accuracy of experimental results was assessed with empirical models on the storage modulus behavior of laminates. The empirical model developed by Gibson et al. provided accurate estimates of the storage modulus as a function of temperature and frequency. The remaining empirical models were less accurate and non-conservative estimations of laminates stiffness.

This study investigates an experimental and analytical study on the flexural, failure, and viscoelastic properties of hybrid and non-hybrid composite laminates at increasing temperatures and frequencies. Carbon, glass, and hybrids of the two fibre materials with stacking sequences of [0/90]_s were considered, and specimens were prepared via the resin transfer moulding method. Three-point bending and dynamic mechanical analysis tools were used. The failure surfaces of the laminates were examined using a scanning electron microscope. The results indicated that the flexural strength, modulus, and strain at failure of all groups of laminates decreased as the temperature increased. In particular, the storage modulus, damping factor, flexural strength, and flexural modulus properties of all groups of laminates increased as the hybrid ratio decreased on each targeted temperature and frequency test. However, the strain at failure increased as the hybrid ratio increased. Additionally, results obtained from the scanning electron microscope images confirmed that combinations of delamination and debonding failure modes were observed on the stacking sequences of [0]_s and [90]_s layers of bidirectional laminates. Finally, a comparison between the storage modulus results of all groups of laminates was conducted with three empirical models. The empirical model developed by Gibson et al. provided the most accurate prediction for all groups of laminates in the targeted temperature and frequency range. The predictions using the remaining empirical models were broadly similar. Further work is needed to optimise the empirical parameters and minimise the errors.

MODULAR RECONFIGURABLE MACHINE TOOLS: DESIGN, CONTROL AND EVALUATION

Purpose: The purpose of this paper is to propose a decision support system (DSS) that stabilizes the flow of fixtures in manufacturing systems. The proposed DSS assists decision-makers to reuse or adapt the available fixtures or to manufacture new fixtures depending upon the similarity between the past and new cases. It considers the cost effectiveness of the proposed decision when an adaptation decision is passed. Design/methodology/approach: The research problem is addressed by integrating case-based reasoning, rule-based reasoning and fuzzy set theory. Cases are represented using an object-oriented (OO) approach to characterize them by their feature vectors. The fuzzy analytic hierarchy process (FAHP) and the inverse of weighted Euclidean distance measure are applied for case retrieval. A machining operation is illustrated as a computational example to demonstrate the applicability of the proposed DSS. Findings: The problems of fixture assignment and control have not been well-addressed in the past, although fixture management is one of the complex problems in manufacturing. The proposed DSS is a promising approach to address such kinds of problems using the three components of an artificial intelligence and FAHP. Research limitations/implications: Although the DSS is tested in a laboratory environment using a numerical example, it has not been validated in real industrial systems. Practical implications: The DSS is proposed in terms of simple rules and equations. This implies that it is not complex for software development and implementation. The illustrated numerical example indicates that the proposed DSS can be implemented in the real-world. Originality/value: Demand-driven fixture retrieval and manufacture to assign the right fixtures to planned part-orders using an intelligent DSS is the main contribution. It provides special consideration for the adaptation of the available fixtures in a system.

The implementation of haptic feedback utilizing a force sensory system in conjunction with a biologically inspired gripper system can improve human-robot collaboration for Reconfigurable Manufacturing Systems. Robot intelligence regarding haptics in manufacturing environments possesses the potential to improve production responses to on-demand production lines. The robotic gripper system was developed from the working principles of the Fin Ray Effect ^® . Adaptability of grasping and object geometric conformity was examined to determine the gripping characteristics of the end-effector. The actuation control through active haptic feedback of the gripper was investigated to determine grasping response and force signal regulation of object retention. The processing signal values through an Arduino ^® data acquisition system provided a characteristic curve of self-conformity properties of the gripper system. The study provided an experimental methodology of testing technical monitoring for force application and deformity study of flexible grippers of the same nature. The outcome from experimental techniques contributed to understanding geometric conformity for biologically inspired grippers for sensitive handling of fragile components and unsymmetrical geometries.

Glass and carbon fibre composites and hybrid glass/carbon composites are materials often used in wind turbine blades. In Africa wind turbines have to operate in warm climates. The present study presents the results of an experimental study on the mechanical properties of these composites at elevated temperatures. For this purpose, the composite specimens are fabricated by hand lay-up process to investigate their static and dynamic properties at high temperatures. The properties studied include Inter-laminar Shear Stress (ILSS), Dynamic Mechanical Properties (DMA) such as storage modulus, loss modulus and loss factor using ASTM standards. The inter-laminar shear failure strength of carbon fibre and hybrid glass-carbon fibre composites are found to be close whereas the glass transition and damping behavior of the hybrid composites are higher making them suitable for wind turbine blades operating at high temperatures. Short Beam Shear (SBS) test data are evaluated using chi-square goodness of fit statistical tests and the correlation coefficients from linear regression analysis are determined. Normal, lognormal and 2-parameter Weibull statistical distributions are used at 5% significant level.