Applied Mechanics and Materials Vol. 909

Abstract: The dynamic vulcanization technique is a process of crosslinking an elastomer during mixing with a molten state thermoplastic, resulting in a new class of thermoplastic elastomers (TPEs): vulcanized thermoplastics (TPVs). This technique obtains materials with rubber behavior at room temperature, but processed as plastics at high temperatures, especially by extrusion and injection. The advantage of using the process of obtaining thermoplastic elastomers is that traditional elastomers require several steps in their processing. From an environmental point of view, vulcanized thermoplastics are interesting, since these materials keep their properties practically unchanged with direct recycling, without the need for any treatments. The objective of this work was to develop a new system of reactive compatibilization for the PP/NBR mixture, by means of the click chemistry technique by the reaction of the thiol-ene type, using as a compatibilizing agent the addition of EVASH (Poli (ethylene-co-alcoholicvinyl)-co-mercapto-vinyl acetate), resulting from the chemical modification of EVA (poly (acrylonitrile-co-butadiene)) with mercaptan groups by transesterification. The ionic liquid acted as a catalyst, optimizing the transesterification reaction of EVA, to obtain EVASH with a greater presence of -SH to EVA, obtaining more rigid systems due to the click thiol-ene bond.

Abstract: This paper presents the peridynamic (PD) numerical model for simulating a tensile test until total fracture for a brittle polymeric material namely polymethyl methacrylate (PMMA). U-notched and V-notched specimens were used to investigate the effect of the notches on the elongation and fracture of PMMA. The tensile elongation of PMMA exhibits nonlinearity with respect to the applied load, while the fracture occurs when the material stress has reached the ultimate tensile stress of the material. Similar elongation and fracture properties were applied on PD simulations. Two types of elongation equation are used namely brittle and ductile equations to form PD-brittle and PD-ductile models. The published experimental data of tensile fracture test on notched PMMA specimens are used as reference to validate the simulations of the PD models. The PD numerical force-extension curves have good quantitative similarity for V-notched specimen but adequate quantitative similarity for U-notched specimen. As for the quality of the fractured specimen shape, the PD simulations have good similarity for the V-notched specimen but adequate similarity for the U-notched specimen. The plot of the internal force distribution from the simulations of PD shows good qualitative similarity to the plot of the stress distribution from the published data of FEM in terms of stress concentration. From the PD results, it is observed that the PD-ductile model has better capability in producing accurate simulation of the notched specimens than the PD-brittle model.

Abstract: In this paper, a higher order shear deformation theory is used to analyse the thermo-mechanical bending response of perfect-imperfect rectangular plates for hybrid ceramic and metal type (FGP) functionally graded plates with porosities. Based on the mixing law, the FG porous material qualities fluctuate with the thickness of the FGP layer. The equilibrium equations are found using the total potential energy approach. For simply supported (FGP) porous plates, the thermo-mechanical response is calculated. Analytical research shows the correctness of the existing high-order shear deformation theory in predicting the thermo-mechanical response of perfect-imperfect rectangular FG plates. Geometric characteristics, thickness ratios, gradient indices, porosity coefficients, mechanical loading, and thermal loading are all covered. According to the findings, the proposed hypothesis is more likely to be correct when it comes to the thermo-mechanical response of FG porous plates.

Abstract: The purpose of this study was to design porous implants with particular structure and evaluate their biomechanical behavior. Thus, a segmented porous dental implant (SPDI) was designed and manufactured by 3D Printing and computer numerical control (CNC) composite machining technology. The FE analysis was used to investigate its static mechanical property. Fatigue test was performed to verify its fatigue life. Resonance frequency analysis and pull-out tests were carried out to study its primary stability. Results indicated that better stress distribution was observed for SPDI. Fatigue test showed that no fracture or failure occurred in SPDI samples after 8 million cycles. The average implant stability quotient (ISQ) values of the SPDI inserted into the porous and denser artificial bones were 68.7 and 73.0 respectively. The average maximum pull-out force of SPDI extracted from the artificial bones was 347.5 N. This study provided a new structural design and manufacturing method for porous implant. The results suggested that the novel porous implant obtained good mechanical adaptability and primary stability.

Abstract: A total of seven beam specimens were carried out to investigate the shear behavior of reinforced concrete (RC) beams strengthened by carbon fiber reinforced polymer (CFRP) grid with epoxy mortar, considering various shear span ratios, concrete strengths and intervals of CFRP grid. According to the test results, the nonlinear regression analysis was conducted and further a prediction method of shear capacity was proposed for CFRP grid-strengthened RC beams. The results showed that the shear behavior of strengthened beams were obviously improved, mainly due to CFRP grid. The shear strengthening effects of CFRP grid not only had a relation to the intervals of grids, but also were closely related to the shear span ratios and the concrete strengths, and thus both of them also cannot be ignored in design. The novel prediction method proposed in this paper, was verified by collecting data and regarded as a good predictor.

Abstract: In this paper, through the construction simulation of the installation and jacking of a large steel grid project, ANSYS software is used to select the corresponding finite element module, and by analyzing the construction models of different modes and different load conditions, the analysis results and structural models are displayed. The 12 supporting hydraulic jacks can meet the overall steel structure hoisting requirements on site. At the same time, the calculation model takes into account the deformation of the overall grid during the unloading process. After testing, the maximum displacement is 7mm, which meets the requirements of national regulations. This method better supports the construction guidance, and also achieved good benefits during the on-site implementation process. The installation plan and jacking technology are worthy of reference.

Abstract: Non-destructive evaluation of structures is a key procedure in operation of aircraft structures, necessary to maintain their quality and integrity. Numerous non-destructive testing (NDT) techniques have been adapted to inspect aircraft structures and are currently used according to appropriate protocols. However, many of them provide only qualitative results, such as the D-Sight optical NDT technique used for inspections in aviation. In this study, a concept of improvement of the D-Sight technique is proposed by means of appropriate experimental program and processing procedures applied to the resulting images from inspection. It was demonstrated that appropriately selected processing methods may allow assessing damage quantitatively and improve the overall sensitivity and applicability of a given NDT technique.

Abstract: Nowadays, the industry requires automatic production for high-speed manufacturing. However, the products must also maintain high quality and reliability. An efficient inspection technique should be conducted for the improvement in the manufacturing quality. In order to achieve high inspection rate, optical inspection based on machine vision often raises the threshold of the judgment and this will worsen false detection. In this study, we propose a high-accuracy optical inspection system based on deep learning technology. Various defects in screw head are precisely detected and analyzed, which include surface damage, unprocessed, and stripped surfaces. An industrial camera and microscope system are employed to collect the raw images of metal screws with different defect types. The raw images of 3200 are utilized to train the designed convolutional neural networks. The experimental results indicate that the proposed system reaches a detection accuracy of 92.8% and the average detection speed is 0.03 second per image. In comparison with conventional machine vision methods, the proposed measurement system is more suitable for the inspection of industrial production line.

Abstract: Abstract. Triboelectric nanogenerators (TENG) have made significant progress as a sustainable energy harvesting technique due to their ease of assembly, high power density, good stability and cost-efficiency. This study develops the magnetic structured triboelectric nanogenerators (MS-TENG) for energy harvesting with different loading frequency. The MS-TENG use magnetic force in the sliding mode to provide the repulsive force. The dielectric and electrode components, in particular, are appropriately connected to the circuit, which is attached to the digital oscilloscope for voltage performance. The copper capsules in mode two were the most effective design for the MS-TENG. The highest load-circuit voltage of 4.0 V is obtained for the copper (Cu) MS-TENG in mode 2 (dielectric capsule designed in mode 2 is first coated with a layer of Cu or Al and then covered with Kapton). A peak power in this design is 3.4 µW. The suggested MS-TENG offers a practical way to gather electrical energy via the triboelectric effect, which are suitable for multifunctional applications.