Polylactic acid (PLA) and polycaprolactone (PCL) are synthetic polymers that are extensively used in biomedical applications. However, the PLA/PCL blend produced by ball milling, followed by pressure compaction and sintering, has not been extensively explored. The goal of this research is to investigate the effect of the composition of biomaterials derived from PLA and PCL prepared by ball milling, followed by pressure compaction and sintering, on mechanical and physical properties. PCL and PLA with various concentrations were blended utilizing a ball milling machine for 2 h at an 80-rpm rotation speed. The obtained mixture was placed in a stainless steel 304 mold for the compacting process, which uses a pressure of 30 MPa to create a green body. The sintering procedure was carried out on the green body created at 150 °C for 2 h using a digital oven. The obtained PLA/PCL blend was tested using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), density, porosity, and three-point bending. Following the interaction between PCL and PLA in the PLA/PCL blend, the FTIR spectra and XRD diffractograms obtained in this work revealed a number of modifications in the functional groups and crystal phase. The 90PLA specimen had the best mechanical properties, with a maximum force and displacement of 51.13 N and 7.21 mm, respectively. The porosity of the PLA/PCL blend decreased with increasing PLA concentration so that the density and flexural properties of the PLA/PCL blend increased. The higher PCL content decreased the stiffness of the PLA molecular chain, consequently reducing its flexural properties.

Hydroxyapatite has the closest chemical composition to human bone. Despite this, the use of nano-hydroxyapatite (nHA) to produce biocomposite scaffolds from a mixture of polylactic acid (PLA) and polycaprolactone (PCL) using cold isostatic pressing has not been studied intensively. In this study, biocomposites were created employing nHA as an osteoconductive filler and a polymeric blend of PLA and PCL as a polymer matrix for prospective usage in the medical field. Cold isostatic pressing and subsequent sintering were used to create composites with different nHA concentrations that ranged from 0 to 30 weight percent. Using physical and mechanical characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and density, porosity, tensile, and flexural standard tests, it was determined how the nHA concentrations affected the biocomposite’s general properties. In this study, the presence of PLA, PCL, and nHA was well identified using FTIR, XRD, and SEM methods. The biocomposites with high nHA content showed intense bands for symmetric stretching and the asymmetric bending vibration of PO43−. The incorporation of nHA into the polymeric blend matrix resulted in a rather irregular structure and the crystallization became more difficult. The addition of nHA improved the density and tensile and flexural strength of the PLA/PCL matrix (0% nHA). However, with increasing nHA content, the PLA/PCL/nHA biocomposites became more porous. In addition, the density, flexural strength, and tensile strength of the PLA/PCL/nHA biocomposites decreased with increasing nHA concentration. The PLA/PCL/nHA biocomposites with 10% nHA had the highest mechanical properties with a density of 1.39 g/cm3, a porosity of 1.93%, a flexural strength of 55.35 MPa, and a tensile strength of 30.68 MPa.

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This paper investigates the influence of T6 post-weld heat treatment (PWHT), and welding orientation on the strength and microstructure of tungsten inert gas (TIG) welded AL6061 aluminum alloy. The TIG process was used to weld the AL6061 at the transversal and longitudinal orientations with reference to the rolling direction. The T6-PWHT is a two-phase heat treatment process, and was applied to AL6061 in order to increase its strength. This T6 was carried out under three different artificial aging; 8, 18, and 24 hours. The influence of PWHT and welding orientation on the strength of AL6061-T6 were investigated through a series of tensile and microhardness tests. In addition, the microstructure observations were performed using the optical and scanning electron microscopes. It was established that the strength and microstructural characteristics of AL6061 are significantly dependent on the T6 artificial aging. Accordingly, the improvements in the strength and ductility were mainly contributed by the grain growth and subsequent precipitate strengthening. Moreover, the welding orientation only affects their fracture surfaces and locations after tensile testing.

Improvement of heat transfer using surface protrusion (convex strip) has been effective recently. Surface protrusion is able to improve flow mixing which increases the rate of heat transfer. Therefore, this study aims to improve the heat transfer in a fin-and-tube heat exchanger by fitting convex strips around the tubes. Three-dimensional modeling was carried out by placing four and eight convex strips around the staggered tubes at a constant temperature of 106 • C. The turbulent k-ε model was applied at a Reynolds number range of 3438-15,926.The results of the study indicate that tubes with eight convex strips demonstrated a heat transfer improvement of 40.46%, compared to that with four convex strips. In this case, the TEF is 6.27% higher than the four convex strips. In addition, the synergy angle in the eight convex strips configuration was 0.13% lower than that of the four convex strips configuration. Meanwhile, the flow resistance in the tubes with eight convex strips configurations was 30.96% higher than that of the four convex strips.

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Load and deformation in the calcaneal/heel region are often studied because of their potential for pain. Research conducted before proved that the calcaneal region receives large loads, both standing and walking, mainly due to excessive body weight. While heel pad deformation is not always associated with body weight, but its influenced by the mechanical properties of plantar soft tissues. In the older person the deformation of the calcaneal region while standing is lower than the adult person, which indicates the loss of the elasticity of the heel pad in aged adults. The aim of this study is estimating deformation of calcaneal area while standing from the Boolean Operation between 3D and footprint image of foot which is a novelty. Thirteen patients who feel pain due to calcanea spur were asked to volunteer research (3 males and 10 females, age 56 ±10 years old, and BMI 25.53±3.74 kg/m 2 ). The 3D image is obtained from 3D scanner for foot orthotics, while the 2D footprint image is obtained from the digital footprint scanner. To determine the accuracy of this method compared with the deformation result of lateral x-rays due to its own weight.

With the increased emphasis on the use of recyclable bio-based materials and further understanding of the mechanical properties of laminated bamboo, the development of a new generation of low-cost bamboo-based composites for ship structure has generated a significant interest. Laminated bamboo composites comprising Apus bamboo (Gigantochloa apus) and Waru fiber at different layer orientations were investigated to obtain the mechanical characteristics. The influence of different laminate directions was studied through several methods of mechanical testing, including impact tests using ASTM D256, bending tests using ASTM D7264, and tensile tests using ASTM D3039. Results showed that material strength properties could be improved by using on-axis direction (0°). The bamboo composites with unidirectional (0°) laminate direction exhibited superior mechanical properties to bidirectional laminate directions (45°/−45° and 0°/90°). The addition of Waru fiber improved the mechanical properties of the currently developed material; that is, bending strength increased by about 3.17–14.18% and tensile strength was in the range of 4.88–20.28%. Only those composites with 0° and 0°/90° layer orientations fulfilled the Indonesian Bureau Classification strength threshold.