Papers by Keyword: Tensile Properties

Abstract: Additive manufacturing of polymeric foams via Material Extrusion (MEX) is an attractive route to lightweight components with tunable mechanical response. However, reproducible performance remains challenging because foam expansion, cell stabilization, and inter-layer bonding are strongly governed by the thermal–processing window. This study evaluates the feasibility of directly printing a commercial PLA foaming filament and quantifies the influence of nozzle temperature (and the associated flow-rate adjustment) on density and tensile behavior. ISO 527-2 tensile specimens were printed under three printing-condition combinations, a nominal PLA setting (190°C, 100% flow) and two foaming-window settings (250°C, 55% flow and 270°C, 50% flow). Tensile tests were conducted, and the tensile properties were assessed via Young’s Modulus, Yield and Ultimate properties (stress/strain), and elastic and total absorbed energy up to fracture. In addition to absolute values, all relevant metrics were normalized by relative density to enable robust comparisons across foaming levels. Finally, the DIC maps at the Yield and Fracture point were used to support the derived results and conclusions.

Abstract: In order to find optimal intercritical annealing treatment (IAT) temperature and alloy composition for simple process route of hot rolling followed by single-step IAT, the effects of IAT on three different medium-manganese steels were investigated. Nominal chemical compositions in wt.% were 1) 6Mn–0.3C, 2) 6Mn–0.4C and 3) 8Mn–0.4C(–2Al–1Si–0.05Nb–Fe). Materials were laboratory hot rolled to a thickness of 6 mm, and IAT was simulated with Gleeble 3800 and Linseis DIL L78 DQT / RITA dilatometer. Different variations of IAT included annealing temperatures of 650 °C, 675 °C, 700 °C and 725 °C, with holding time of 10 minutes, heating rate of 50 °C/s and cooling rate of 10 °C/s. Quasi-static tensile tests were performed parallel to rolling direction. XRD and EBSD phase mappings were performed to assess IAT temperatures effect on volume fraction of retained austenite. Most promising mechanical properties were obtained with material 6Mn–0.4C annealed at 700 °C. Product of strength and elongation well exceeded 40 000 MPa% for above-mentioned IAT-material variation, being distinguishable higher compared to other variations. However, investigated materials, especially 6Mn–0.4C, seems to be very sensitive to IAT temperature, which could inflict some challenges in industrial scale production. Also, all materials experienced some level of serrations during tensile testing, which is frequently encountered phenomena with medium-manganese steels. Further research is required, to evaluate the role of austenite stability on mechanical behavior of these materials and to determine effects of heating and cooling rates.

Abstract: Ultra-high molecular weight polyethylene (UHMWPE) laminate composites are widely used in impact-resistant structures due to their high specific strength and exceptional energy absorption capabilities. However, previous studies encountered challenges in characterizing the tensile properties of UHMWPE composites, including specimen slippage, stress concentrations, and failures outside the gauge length. This work presents the design and development of an interchangeable clamp for the tensile testing of UHMWPE composites. This clamp guarantees secure gripping and uniform load transfer across the UHMWPE specimens. The developed clamp can be used interchangeably in quasi-static and high-strain-rate devices, facilitating the evaluation of a broad range of strain rates. The tensile properties of two UHMWPE composites were subsequently assessed using this clamping system, with strain measured through three-dimensional digital image correlation (3D-DIC). The effectiveness of a 3D-DIC technique for measuring strain in the UHMWPE composite is demonstrated. The tests reveal that the designed clamp enables reliable measurements, with tensile strength values reaching approximately 1300 MPa. The measured tensile properties are useful for the input data of numerical simulations, providing valuable insights for developing highly efficient protective structures.

Abstract: Conventional welding of lightweight metals like aluminium and magnesium alloys raises concerns about joint strength and ductility. Conversely, friction stir welding (FSW) improves both by bonding materials through plastic deformation. This study revealed a clear correlation between tool feed rates and the mechanical performance of the joints. At lower feed rates, controlled plastic flow resulted in robust joint formation, enhancing both Ultimate tensile strength and Yield strength. Conversely, escalating the feed rate compromised joint strength due to imperfect joints and inadequate plastic flow. Artificial aging was found to play a pivotal role in enhancing the mechanical properties of FSW joints. Higher feed rates, despite initially leading to reduced ductility, showed improvements in yield strength following aging, primarily attributed to the reduction of flaws and defects within the joints. Artificial aging contributed to elevated yield strength values through grain boundary sizing and precipitate formation. However, it's important to note that the improvement in strength was not uniform across all feed rates, indicating that the influence of post-aging treatment was more pronounced for joints produced at feed rates other than 450 mm/min. Ductility experienced a significant decline (almost 50%) after artificial aging, especially for joints formed at higher feed rates, highlighting the trade-off between strength and ductility. Findings aid FSW optimization, designing joints with desired mechanical traits for applications valuing strength, ductility, and aging effects.

Abstract: Nowadays, the use of rubber products such as tyres, bearings, shoe soles, hoses, and cables are increasing due to its high strain to failure. However, the indestructible cross-linking of sulphur or peroxide chains in vulcanized rubber could complicate the biodegradation, reprocessing, and recycling of rubber products. Due to these crucial problems, the increasing number of rubber-based products worldwide will lead to environmental hazards. An alternative strategy to address this problem is to give elastomers the ability to self-heal, thus promoting their reusability. Zinc diacrylate (ZDA) salt was used as a self-healing agent in NR. The ionic interaction of the self-healing process between natural rubber (NR) and ZDA were investigated, and successful grafting was demonstrated by FTIR analysis. The results showed that NR with 10 phr of ZDA had the highest tensile strength and elongation at break, which was also proved by microscopic images. The image showed no visible gap between the fractured contact surface of NR indicating an efficient self-healing mechanism. Therefore, this study has proven the potential of ZDA as a self-healing agent to NR compound and is expected to pave the way for environmentally friendly rubber products.

Abstract: The non-biodegradable and non-renewable nature of synthetic plastics poses a long-term threat to ecosystems, contributing to environmental pollution and depletion of natural resources. Thermoplastic starch (TPS) is a biodegradable biopolymer and has been identified as one of the best alternatives to replace synthetic polymers, especially in packaging application. In this study, hybrid inorganic/organic fillers were incorporated into the TPS to form hybrid biocomposites films that performed better performance compared to the neat TPS. Oil palm empty fruit bunch (OP) and dolomite (DO) were combined to form the hybrid fillers of the TPS biocomposites in the ratio of 1:4, 2:3, 3:2 and 4:1. Neat TPS was also prepared as control sample. The effect of thermo-oxidative aging on the mechanical properties of all the samples was evaluated. The structure of all samples was assessed using. X-ray Diffraction analysis (XRD) and X-ray Fluorescent (XRF). Based on the results, the TPS films with the hybrid fillers exhibited 61 % increment in tensile strength compared to the neat TPS films. In this study, OP4DO1 is best loading of the hybrid fillers to incorporated in TPS matrix as it achieved the highest value of tensile strength (5.61 MPa), modulus of elasticity (66.13 MPa) and elongation at break (59.93 %). Apparently, this study demonstrates a significant improvement in the tensile properties of the TPS when incorporated with these OP/DO hybrid fillers, thus indicate the potential of utilizing this TPS hybrid biocomposite in packaging applications.

Abstract: Due to emerging global environmental awareness, the increasing demand on synthesizing green materials for structural purposes became prevalent. This study utilized agricultural, aquacultural, and industrial waste as partial replacement for fine aggregates in concrete. One standard and six concrete samples with various proportions (20% and 40%) of rice husk ash (RHA), oyster shell powder (OSP), and ferrous powder (FeP) were constructed and tested for their mechanical properties (i.e., compressive and split tensile strength). The samples containing 20% and 40% FeP attained the highest compressive (22.71 MPa) and split tensile strength (1.379 MPa), respectively, which are closest to the control, M25 grade concrete (C-M25), (23.87 MPa), and (1.44 MPa), respectively. Concrete fracture analysis indicated that the cylinders were well constructed as implied by the fracture types. The C-FeP is the best concrete mixture attaining superior compressive and split tensile strength values.

Abstract: Waste eggshell powders with a particle size of less than 0.315 μm were surface treated with vinyltrimethoxysilane. XRD, FT-IR, BET and SEM analyses were used to determine the surface characteristics of eggshells before and after silane treatment. The preparation of films of unplasticized suspension polyvinyl chloride with untreated and silane-treated eggshells was done by co-precipitation of solutions from cyclohexanone. The tensile properties of obtained films containing vinyltrimethoxysilane-treated eggshell powders were investigated and analyzed relative to the compositions with untreated powders.

Abstract: Due to its mechanical, rheological, and chemical properties high-density polyethylene (HDPE) is commonly used as a material for transport of various media. Low thermal conductivity (0.37 W/mK) limits usage of HDPE in the heat exchanger systems. This property can be improved by adding 20% synthetic carbon to the PE matrix which increases the thermal conductivity by 345% compared to the initial value of the thermal conductivity of pure PE. But this filler has an effect on the mechanical properties too, by enhancing or degrading them. Recently attempts have been made to reduce waste in all possible ways so the second direction of obtaining carbon in this paper is from household biological waste. The mentioned wastes contain cellulose, which is the most abundant carbon precursor. The bio-based carbon was prepared from the kitchen waste, especially from the remains of root vegetables like carrots, parsley, and potatoes. Synthetic carbon retains the same tensile strength as pure PE, while in PE with carbon from bio waste, the strength is reduced by 5 MPa, while the tensile modulus of the composite in both cases increases; in the case of carbon from kitchen waste by 25%, and in the case of synthetic carbon by 100%. In addition to PE, tests were also carried out on polypropylene (PP) to see any potential application for these two most common polyolefins.

Abstract: Friction stir welding is a non fusion solid state welding technique where sheets are welded with application of frictional heat and pressure together. In this welding process, the tool pin geometry plays a crucial role for development of good quality welded joints. In this work, Al6061 and Al2014 aluminium alloy plates were welded with use of three different tool pin geometries such as straight square, straight hexagonal and taper threaded. Tensile properties and hardness of the welded joints were evaluated. From the results, the welded joints developed with straight square geometry tool tensile properties are better than the welded joint developed with straight hexagonal and taper threaded profiled tools. The better properties are due to pulsating action and higher dynamic volume to static volume ratio of the straight square geometry tool. A microstructural evaluation revealed that formation of more homogeneous distribution throughout the weld nugget for the welded joint made with straight square geometry pin tool.