The effect of the chemical composition of geopolymer pastes on compressive strength was investigated in high-calcium fly ash and copper slag blends. In synthesizing the pastes, soda ash at activator to binder ratio of 0.4 was used. The characterization of material samples and the hardened fly ash-copper slag pastes was conducted through X-ray fluorescence (XRF), and X-ray diffraction (XRD) for the major oxide and phase composition. The hardened paste cubes which were cured at 80 °C were tested for compressive strength at ages 3, 7, and 28 days to obtain the mechanical performance property of each respective mix. The findings establish the impact of variation in the individual material and paste composition on the compressive strength of fly ash-copper slag geopolymer. The result shows that increase in the SiO₂/Al₂O₃ and Na₂O/Al₂O₃ ratios of paste products of samples corresponded to an increase in compressive strength. Whilst Fe₂O₃ wt.% increase in products from slag addition and positively influenced the compressive strength as fillers. However, CaO had no positive influence on the matrix of the activated product. The optimal blend mix design was 40 wt.% of copper slag which achieved a 28-day compressive strength of 24.66 MPa.

Polyester fibers are the most used in the manufacture of ropes for mooring systems and offshore operation, thus being constantly subjected to different situations. Such requests are implicated in a variety of load conditions, and their effects must be studied. This work presents data referring to an experimental study on the behavior of the quasi-static and dynamic stiffness of polyester yarns considering different mechanical levels of degradation and use. The study is performed with five different types of multifilament samples, these were extracted from a virgin spool and sub-ropes tested for tension and fatigue. The experimental procedure is carried out through an initial characterization where the linear density, the Yarn Break Load - YBL and the linear tenacity of the samples are determined. Continuing with the experimental tests, a procedure standardized by ISO 18962-2 is then carried out, consisting of three quasi-static stages and three dynamic stages, where the data acquired in the tests allow the determination of a dimensionless stiffness value. The results showed an increase in the quasi-static stiffness, tending to a plateau, and a linear increase in the dynamic stiffness, but with somewhat similar behavior between the samples. The results related to the total quasi-static stiffness also show that the specimens extracted from sub-ropes that underwent fatigue present greater total non-dimensionalized stiffness, this is indicative of the mechanical fatigue procedure as an improvement of the specimens, giving them greater stiffness, and consequently greater stresses rupture, a behavior that should be explored in future studies.

The article analyzes the stress-strain state in the zone of plastic deformation during special caliber rolling. The principle of caliber rolling technology is described, which makes it possible to combine shear and compression deformations in the cross-section of metals, alloys, and metal-matrix composites. The analysis results of stresses and strains during shear rolling in a diamond pass, which included compressive strains that had not been considered in previous studies, revealed that localization or point inversion of stresses and strains is observed in the plastic deformation zone. Stress and strain are localized along the minor and major diagonals of the diamond pass.

Additive manufacturing has been one of the most used techniques in the recent years because of its capabilities to fabricate complex structures as required by customer and industrial need from a 3D computer-aided design model without the usage of any tooling, dies and heavy machinery makes it a step ahead in the present manufacturing techniques. In the current study the author’s focus on the welding or joining of additive manufactured Polylactic acid (PLA) parts made by Fused Deposition Modeling (FDM). There are several techniques for welding these additive manufactured parts. This study mainly focuses on the joining of 3D printed PLA parts using a 3D pen and investigations on its mechanical properties experimentally. It is a very cheap and effective technique when compared to the other welding methods. This could overcome the drawback of small bed size in most 3D printers by joining smaller parts and it can also be used for repairing the defects caused during the 3D printing. Moreover the experimental testing of the mechanical properties also confirmed that the tensile, flexural and impact strength of 3D pen welded specimens retrieved above 70% of the strength to the original PLA specimen proving it to be a very effective method.

There is no rationalization for a certainty that harder wheels or rails will result in an increase in wear of the opposite side of the wheel/rail interface. This research investigated how the wear of wheel material changes when the hardness of the opposing pair is varied. Three Rail/wheel material matches; normalized UIC50 kg/m and S1002 wheel profile (Rail/wheel material 1), normalized UIC60 kg/m and whole heat treated S1002 wheel profile (Rail/wheel material 2) and rim heat treated UIC60 kg/m and whole heat treated S1002 wheel profile (Rail/wheel material 3) has been investigated using multi-body simulation software (SIMPACK) and MATLAB programming. For validation, as an experimental advantage, the wear depths measured on the wheel tread wear of the end vehicle of LRT for mileage of 50,000 km are compared to the results of numerical simulation performed. As a result, the estimated total tread wear amount after a mileage of 50,000 km is 4% larger than the experimental one. That is indeed a very good result considering that either component of the wheel wear prediction model used is neither adjustment nor calibration. From the three rail/wheel matches, Rail/wheel material 3 found to be the better material match that could resist wear significantly considering material hardness as important criteria for comparison. The study could remark that, despite the fact both wheel and rail material hardness could affect the wear performance in respected positive ways, most significant improvements are attained by improving the rail material hardness ahead of wheel material.

Glass Fiber Reinforced Polymer (GFRP) is a polymer composite material used in lightweight structures. This study provides insight into achieving robust GFRP H-section short-column spliced connections using bonded, bolted, and hybrid connections. The design specifications for steel splicing connections are based on BS EN 1990 and BS EN 1991 guidelines. Based on the samples subjected to axial loading, factors such as compressive strength, bonding and bearing resistance, compression behavior of the connection, and failure modes of the structure are investigated. The study includes the behavioral characteristics and results of 25 GFRP H-section Spliced connections, with each H-section measuring 152 x 72 x 6.4 mm and standing 350 mm in height. This study also examines the behavior of a composite splice joint made up of steel cover plates and steel bolts that are used to create an ideal non-bearing spliced connection. This model is used to compare to the other models to understand the behavior of spliced joints designed with GFRP cover plates. This paper holds design specifications of connections that have displayed compressive strengths of 82.35 %, 89.82 %, and 92.83 % compared to that of an un-cut GFRP H-section subjected to axial loading.

The present work investigates Rotary Friction Welding (RFW) of AA2024 similar joints, where the welding operations were carried out using an adapted device to a column-drilling machine (SUPEMEC J320). This work aims to determine the optimal RFW parameters from an experimental study based on mechanical tests and microscopic observations of weld joints. The best compromise, which offers the highest tensile strength value (499 MPa) corresponds to the joint obtained by using a rotational speed of 2000 rpm, a friction pressure of 12 MPa, and a forging pressure of 17 MPa. The EDX results indicate the presence of the intermetallic compounds (IMCs) in each zone of the weld joints, with varying sizes and a random distribution. This study focuses also on the microscopic analyses of the interface of weld joints and the fracture surfaces that indicates a dominant ductile fracture mode.

This work is interested with a thermoelastic response in a micro-stretch half-space submerged in an unlimited non-viscous fluid under rotation, the medium is studied using the theory of Green-Naghdi (G-N III) and the model of three-phase-lag (3PHL). The governing equations are formulated in the context of G-N theory and the 3PHL model. Analytical solution to the problem is acquired by utilizing the normal mode method. The magnesium crystal element is utilized as an application to compare the predictions induced by rotation on microstretch thermoelastic immersed in an infinite fluid of G–N theory with those for the 3PHL model. Rotation has been noticed to have a major effect on all physical quantities. Comparisons were also made for three values of wave number b and three values of the real part frequency ω0.

The article reports on the workability of two P92 steels having a chromium content of 8.29 and 9.48 wt%. Constitutive equations were used to calculate material parameters describing the hot deformation flow stress. Hot deformation tests were conducted using the Gleeble® 3500 thermomechanical facility. Test conditions were: temperature of 850-1000°C and strain rate of 0.1-10s-1 to a strain of 0.5. The flow stress curve results show that dynamic recovery was the only softening mechanism. A comparative study of the two steels revealed that Cr content had a marginal significance on the flow stress behaviour. Constitutive analysis results of the material parameters were: a stress exponent of 9.0 (P92-A), and 11.0 (P92-B), while the activation energy was 369 kJmol-1 (P92-A), and 472 kJmol-1 (P92-B). A brief explanation of the material parameter results is in this article. A flow stress model was developed to predict the flow stress behaviour of the two P92 steels investigated. The results show that the model accurately predicts the flow stress at all the deformation conditions applied. The statistical parameters showed a good correlation between the predicted and the experimental data. Therefore, this model can be used to develop metal forming schedules for industrial applications.

Recently, due to their extraordinary strength-to-weight ratio and multi-functional applications, three-dimensional woven fiberglass sandwich structures have become a well-received topic by researchers and manufacturers. Nevertheless, using light and foam absorber materials as injected fillers within sandwich cores can improve their overall mechanical performance and, in particular, their fracture toughness behavior. This study evaluates the fracture toughness of three-dimensional woven fiberglass sandwich panels filled with natural nano-structured zeolite/polyurethane foams injected between their parallel panels. The Single-Edge Notched Bend test was carried out to understand the effect of the injected foam on the mode-I fracture toughness response. It is demonstrated that the polyurethane foam reinforced with natural nano-structured zeolite particles highly improved the fracture toughness of sandwich core panels. It was found that the presence of vertical glass yarns within the sandwich panel gallery resulted in a significantly higher toughness compared with typical sandwich panels of no reinforcing vertical columns confirmed by the crack propagation and observed failure mode. The SEM and EDX analyses were used to better understand the correlations amongst the specimen morphology, the cracks behavior, and the toughness exhibited by the fabricated specimens.