Effect of Ground Tire Rubber on Mechanical Properties of Low Density Polyethylene

This research explores the effect of ground tire rubber (GTR) on the mechanical properties of LDPE. This thermoplastic-elastomer blend sets the composition of ground tire rubber and low-density polyethylene (LDPE/GTR). The blend was prepared in different proportions and was processed in a compression molding machine. The optimum operating conditions of the blend set to be 220℃ temperature and pressure varied from 150-200 bars. Different parts per hundred rubber (phr) samples were obtained under these conditions, including 1 phr, 2 phr, 3 phr, 4 phr, and 5 phr. After that, the mechanical properties of the blend were examined concerning various compositions. Different testing methods were used to determine the mechanical properties of the thermoplastic-elastomer blend, which include tensile strength, flexural strength, and Izod impact. The results obtained from these tests show that tensile strength and modulus decreases by increasing the rubber content. However, impact strength and percentage elongation increase by increasing the rubber content. This enhancement in impact and percentage elongation may be suitable for the applications in gymnasium mat and automobile industry.

TENSILE AND STRETCH OF PAPER FILLED WITH BACTERICIDAL ZEOLITES

The purpose of present work was to study tensile and stretch of paper prepared with the use of bactericide zeolite fillers containing up to 130 mg/g of silver, 72 mg/g of copper, and 58 mg/g of zinc, prepared by ion exchange reactions using heulandite-clinoptilolite from the Rkoni plot of the Tedzami deposit, Eastern Georgia. Filled papers with zeolite content up to 4 g/m2 and bactericidal activity confirmed by the colony forming unit assay were manufactured on the production lines of the GPM enterprise (Tbilisi, Georgia). The measured tensile strength and percentage elongation of filled paper depend on the nature of the filler and its metal content; the introduction of pure zeolite filler reduces the tensile and stretch of the paper, but fillers containing silver and copper increase the tensile strength. Accelerated aging results in lower tensile and stretch, but zeolite fillers generally make the paper more resistant to aging.

COMPARATIVE STUDY OF THE REINFORCED STEEL BARS OBTAINED FROM A FAILED RESIDENTIAL BUILDING AND THE SHELVES

Nigeria is a developing nation, the need to build structures is on high rise. The rate of structure failure and building collapse is also on the rise. This paper presents a comparative study on Mechanical Properties of Reinforced steel bars obtained from the shelves, and that obtained from the failed structure of a residential building which is then compared to International standard NO-432 . Steels are main reinforcing materials for most structural buildings, but when the integrity is compromised, it leads to devastating consequences. The quality of concrete and steel reinforcement must be such that has appropriate yield strength so that the structure can sustain the require load within the required time interval. The Ultimate Tensile Strength and percentage elongation of the steel bars obtained from the two sources were investigated. One of the sources was a reinforcing bar used in Millennium Estate, Mary Land, Lagos State, Nigeria. The steel bar samples of sizes 10mm and 16mm diameter were subjected to mechanical testing using a universal testing machine. The percentage elongation met with the standards while the 16mm samples are below the standards for both the failed structure and shelves.

Tensile and flexural behaviour of graphite filler particles and pineapple leaf fiber (palf) reinforced polymer composites

New composites materials are developed to meet the demand for medical devices, vehicles, protective equipment, sporting goods, etc. In present investigations, the effects of graphite filler particles in the epoxy were studied separately by preparing epoxy with 5 and 10 vol.% of graphite filler particles composites by hand layup technique. Further, the combined effect of graphite filler particles and pineapple leaf fibers (PALF) on the mechanical behaviour of epoxy composites was studied by preparing epoxy with 5 vol.% of graphite -30 vol.% of PALF and epoxy with 10 vol.% of graphite -30 vol.% of PALF composites. Prepared composites were subjected to evaluating various mechanical properties like tensile strength, elongation, and flexural strength as per ASTM standards. By adding graphite filler particles and PALF fibers tensile, and flexural strength were improved with a slight reduction in the percentage elongation. Further, these conventional results were validated by FEM analysis using MSC Patran and Nastran Student Version.

Experimental investigation and optimization of quality characteristics during friction stir welding of Al- and Zn-based magnesium alloy using artificial intelligence

Friction stir welding is successfully used to weld different wrought magnesium alloys. This work investigated the mechanical and microstructural behavior of the friction stir-welded AZ31B magnesium alloy. The experiments were conducted as per experimental runs designed by response surface methodology. An artificial neural network model was developed to produce a relationship between process variables (tool rotational speed, welding speed, and tool shoulder diameter) and characteristics of the friction stir-welded joints (tensile strength, percentage elongation, impact strength, microhardness, and grain size). The acceptable range of statistical parameters validated the adequacy of the model. The multi-objective optimization technique, genetic algorithm was used to obtain a set of Pareto optimal solutions. The best-compromised optimum solution for maximum tensile strength (164.2 MPa), percentage elongation (8%) impact strength (3.5 J), microhardness (85 Hv), and minimum grain size (13.1 μm) was validated by confirmation test with <3 percent absolute error percentage. The fractographical analysis has been performed and dimples and torn edges observed in fracture zones.

Mechanical Property Comparison of Ni–Cr–Mo Alloys Fabricated via One Conventional and Two New Digital Manufacturing Techniques

This study compared the microstructures and mechanical properties of nickel–chromium–molybdenum (Ni–Cr–Mo) alloys prepared from a single alloy with an identical composition using two new digital processes (selective laser melting (SLM) and soft metal milling (SMM)) and conventional lost-wax casting (LWC). Disc specimens were used to study the microstructures via various analytical methods, while dumbbell-shaped specimens were subjected to tension to determine the mechanical properties (n = 6). The SLM and SMM alloys showed a higher number of large and small pores, respectively, than the LWC alloy. A face-centered cubic (γ)-phased matrix was indexed for all three resultant alloys. The SLM and SMM alloys also showed more homogeneously distributed elements and finer grains (in particular, ultrafine grains in the SLM alloy) when compared to the LWC alloy. Meanwhile, the LWC alloy showed a statistically higher yield strength than the other two alloys (p < 0.001). Notwithstanding, all three resultant Ni–Cr–Mo alloys satisfied the ISO 22674 standard criteria for type 5 materials (yield strength: >500 MPa; percentage elongation: >2%; and elastic modulus: >150 GPa).

Microstructural and mechanical studies of feedstock material in continuous extrusion process

The challenge encountered in continuous forming process is the variation in mechanical strength of product formed with respect to process variables like extrusion wheel speed and diameter of product. In this research article, the micro-structural investigation of the aluminum (AA1100) feedstock material of 9.5-mm diameter has been carried out at various extrusion wheel speeds and diameter of product before and after deformation on commercial continuous extrusion setup TBJ350. The mechanical properties like yield strength as well as percentage elongation have been estimated and optimized using two variables with 3 levels through central composite rotatable design (CCRD) method. The mathematical modeling has been carried out to predict the optimum combination of process parameters for obtaining maximum value of yield strength and percentage elongation. The statistical significance of mathematical model is verified through analysis of variance (ANOVA). The optimum value of yield strength is found to be 70.939 MPa at wheel velocity of 8.63 rpm and product diameter of 9 mm respectively, whereas the maximum percentage elongation recorded is 46.457 at wheel velocity of 7.06 rpm and product diameter of 7.18 mm. The outcome may be useful in obtaining the best parametric combination of wheel speed and extrusion ratio for best strength of the product.

Process Parameters Optimization for Maximizing Tensile Strength in Friction Stir-Welded Carbon Steel

The present study focuses on improving the ultimate tensile strength of friction stir welded carbon steel (AISI 1018). The effect of the process parameters (welding speed, tool RPM, and shoulder diameter) on the response parameters (ultimate tensile strength, percentage elongation and percentage reduction in area) were studied. Response surface methodology was used to develop the mathematical model for response parameters, and the adequacy of the model was checked using analysis of variance (ANOVA). The welding speed and tool RPM were found to affect the ultimate tensile strength significantly. The percentage elongation was affected only by welding speed. The percentage reduction in the area was affected by welding speed and shoulder diameter. The microstructure and microhardness of the weld have been studied and reported in the study.

Austenite Grain Growth Analysis in a Welded Joint of High-Strength Martensitic Abrasion-Resistant Steel Hardox 450

The paper presents the results of tests of a welded joint of Hardox 450 steel, belonging to the group of weldable high-strength boron steels with increased resistance to abrasive wear. As a result of the conducted research, apart from the basic structural indicators, an attempt was made to determine the correlation between the grain size of the prior austenite in the characteristic weld zones and its basic mechanical properties, such as yield point, tensile strength, percentage elongation after fracture, reduction of area, and impact strength. The scope of research quoted above was carried out for a welded joint of the considered steel at delivery state (directly after welding), in the normalising annealed state, as well as in water-quenched state, using different austenitisation temperatures in the range of 900–1200 °C. The results obtained showed a large influence of the parameters of the applied thermal heat treatment on the selected structural and mechanical properties of the welded joint.

Quantitatively Investigate the Effects of Natural Aging on Mechanical Properties and Bake Hardening Behaviors of Al-Mg-Si Alloys

The effect of natural aging on mechanical properties and bake hardening behaviors of Al-Mg-Si alloys was quantitatively investigated by a series of tensile experiments along the rolling direction. The natural aging period is from three days to three months after heat treatment. As the results, within three months, along the rolling direction, 0.2% offset yield strength and ultimate tensile strength respectively increased from 97 MPa to 145 MPa, 210 MPa to 248 MPa. The strain hardening exponent n-value and the increment of yield strength after bake hardening respectively decreased from 0.2804 to 0.2186, 127 MPa to 89 MPa. The percentage elongation after fracture varies from 22% to 24% during natural aging and varies from 13% to 16% after bake hardening. A large amount of detailed data has been given, which quantitatively describes the change in mechanical properties and bake hardening behaviors of Al-Mg-Si alloys during natural aging.