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This review presents various types of epoxy resins and curing agents commonly used as composite matrices. A brief review of cross-linking formation and the process of degradation or decomposition of epoxy resins by pyrolysis and solvolysis is also discussed. Mechanical engineers are given a brief overview of the types of epoxy resin, which are often applied as composite matrices considering that they currently play a large role in the research, design, manufacturing, and recycling of these materials.

Nozzle hole diameter of 3D printer (3DP) can be varied to obtain required product quality as well as to reduce manufacturing times. The use of larger diameter may accelerate manufacturing times of products, yet the product quality, including the mechanical properties, still needs to be investigated profoundly. The purpose of this work is to investigate experimentally the effect of nozzle hole diameter of 3DP to the surface quality, accuracy, and the strength of the product. The specimens were manufactured by fused deposition modelling (FDM) 3D printing using polylactic acid (PLA) as the filaments.Bed temperature, extruder temperature and printing speed were set to be 60∘C, 200∘C and 80 mm/s respectively. The thickness of each layer was set at the ratio of 20% to the nozzle hole diameter. Infill pattern was determined by using line type of 100%. Nozzle hole diameter of 0.3, 0.4, 0.5 and 0.6mmwas compared in thiswork. The results show that bigger nozzle hole diameter enhanced the density and tensile strength of the products thought it was not linearly correlation.

Hip joint is an important human joints system. The damaged hip joints need to be replaced with artificial hip joints. The Study of the hip joint is very costly therefore another calculation method is demanded to produce good result in acceptable time and cost. Considering this problem, a series of study to assess hip joint performance is conducted using numerical approach. Important parameter for example applied materials are used in the modelling by idealizing Ti-6Al-4V compared to SS 316 L, and stemlengthwas chosen to be 128 mm. ANSYS software was used to analyze models, and designed element size variations were set to be in range 1 to 2.5 mm. The magnitude of force was placed on the femoral head with an angle of 16∘C from the vertical axis. Results showed that SS 316 L material has smaller deformation than Ti material. Whereas Central Processing (CP) time decreases in increasing element size for both materials. In addition, more variations in mesh size are needed to get more accurate convergent results.

Thermosetting epoxy resin polymer with cycloaliphatic amines curing agent has been widely used for a composite matrix with carbon fiber reinforcement. The utilization was increased due to the superior performance of this epoxy resin compared to other polymers. However, a changing operational environment has potentially reduced composite performance, which most likely begins with matrix degradation. This research applies thermal treatment by the quenching process sequence to the epoxy resin matrix and its reinforced carbon fiber composite (CFRP). The composite is made by epoxy resin diglycidyl ether bisphenol-A, curing with cycloaliphatic amine as matrix and strengthening carbon fiber mat/woven. Three times quenching treatment was performed by heating the specimen around the glass transition temperature and then dipped immediately in fresh water. After quenching treatment, the epoxy resin shows a reduction in tensile strength and elongation. Under infrared observation, epoxy resin does not significantly show changes in functional groups. Investigation under X-ray refraction also indicates no difference in a crystalline structure; this epoxy resin stays in an amorphous form before and after quenching. In contrast to the matrix, the quenching treatment of the CFRP composite above the epoxy resin s glass transition temperature revealed an increase in the interlaminar shear strength (ILSS). The matrix ductility reduction after quenching should be carefully considered for application in the form of epoxy resin sheets or CFRP composite construction materials.

Application of metal bone screws for internal fixation has many risks, including infection, temperature sensitivity, and radiologic imaging disturbance. Bioabsorbable bone screws appear to overcome the disadvantages of metal bone screws. Many researchers have developed numerous bioabsorbable bone screws using various kinds of polymers. In this research, polylactic acid (PLA) and polyglycolic acid (PGA) were used as the materials for the bone screw. The injection molding method was used to produce the screws as it is one of the most effective methods in polymer or plastic production. This study aims to understand the effect of injection molding simulation parameters on shrinkage and warpage of bone screw, and to discover the best parameters combination to obtain optimal responses, and compare PLA and PGA bone screws. Injection molding simulation experiments used the Taguchi method, and the optimization process used particle swarm optimization. The results showed that melt temperature, injection time, and packing time had significant effects on shrinkage and warpage of PLA bone screws. Meanwhile, the significant factors for PGA bone screws were mold temperature, melt temperature, and injection time. After the optimization process, the shrinkage and warpage value improved to 2.4233% and 0.0928 mm for PLA bone screws and 8.9592% and 0.4646 mm for PGA bone screws. [ABSTRACT FROM AUTHOR]