Use Of Tensile Tests Research Articles

Identification of factors influencing the quality of extruded profiles using aluminum Recyclate-Based billets

The recycling of aluminium chips by direct processing of the chips in the extrusion process is a metal forming technique which requires less energy than remelting of the chips and prevents further material losses during the remelting process. For this purpose, chips contaminated with lubricant or cleaned chips can be used for the chip-based extrusion. Since the process parameters also influence each other and, in addition, the properties of the chips must be considered as additional parameters, which also have an influence on the success of the process and the quality of the profiles the determination of the factors influencing the process has not yet been completed. Due to previous investigations, it can be determined that the quality of the extruded profiles depends on the choice of the tool concept as well as the extrusion ratio. In contrast to previous studies investigating the influence of die design, chip geometry and compaction route, a porthole die was used in the present experiments. In these experiments, the process parameters such as extrusion speed, temperature, homogenization time were varied and their influence on the mechanical properties was evaluated. Furthermore, a new criterion is presented to evaluate the welding quality of the chips. In experimental as well as numerical investigations, the use of tensile tests and the evaluation of the weld quality showed that the mechanical properties of the profile vary over the cross-section independently of the process parameters. At the same time, the results have shown that in extrusion of chip-based billets, the yield strength, tensile strength and breaking elongation can be significantly influenced by the use of appropriate process parameters.

Investigation of the Effect of T-Consciousness Fields on the Mechanical Properties of Materials

In another study titled “Investigation of the Effect of T-Consciousness Fields on the Mechanical Properties of Materials,” (Authors: Mohammad Ali Taheri, Firouz Payervand, Reza Yazdanparast, Farzad Ahmadkhanlou, Sara Torabi, Farid Semsarha*), by use of tensile testing, the effects of two types of TCFs on the mechanical properties of two types of steel were investigated. The obtained results demonstrated that the strength and brittleness of ST-37 steel increased in dynamic loading conditions under the treatment of TCF 2. Moreover, softening of the ST-37 carbon steel and AISI 4340 alloy steel in quasi-static loading conditions under the treatment of TCF 1 and 2 were observed, respectively. In this experiment, the effects of different types of TCFs on the material were confirmed.

Structural integrity and mechanical properties of the functionally graded material based on 316L/IN718 processed by DED technology

Additive manufacturing is a one of the most promising technology nowadays that offers the advantages not only in building products of complex shapes but also of complex materials. A complex structure is characteristic for Functionally Graded Composites, which basics, principles and applicability have been widely investigated over the last years. The present study is focused on the detailed investigation of mechanical and structural properties of FGC consisting of stainless steel 316L and Inconel 718 processed by Blown Powder Directed Energy Deposition system. Mechanical properties within single layers and over layers transitions were investigated with the use of tensile tests and fracture toughness tests. Metallographic and fractographic investigations were carried out. Metallographic investigation revealed the differences in the interfaces between single material layers, nucleation processes and subsequent growth of the grains of the used materials. It has been shown that the formation of transition region between deposited single material layers is dependent on the order of material deposition since different deposition parameters are used for certain material. Evaluation of the tensile properties showed that the mechanical properties of a single material layers are in very good agreement regardless of the deposition height. However, the types of interfaces considering to the results of fractographic observations affect the tensile performance of the Functionally Graded Composite. The fracture toughness test results demonstrate changes in the mechanism of crack propagation at the interface between materials with respect to the type of transition. Furthermore, the material layers interfaces turned out to be the weakest points of the Functionally Graded Composite. • A great continuation of the Inconel's grains is observed when deposited on 316 L. • 316 L grains show rare crystallographic traceability when deposited on the IN718. • Tensile properties are in very good agreement regardless of the deposition height. • Material layers interfaces are the weakest points of the functionally graded material. • The crack propagation mechanism in FGC is dependent on interface type.

Combined strain rate, mesh size and calibration test influence on structural failure: Miniature ship grounding test

This paper investigates the influence of the strain rate and element size on the fracture of steel plates presented in marine structures undergoing grounding when modeled by the finite element method. Three different experimental tests (tensile, tearing and perforation tests), performed at different velocities, are used in the study. These tests are conceived to cover diverse rupture modes related mainly to crack initiation and propagation. Plastic strain- and stress state-based failure criteria were calibrated from these experiments. Sensitivity to strain rate and mesh size were also evaluated. A ship grounding event was reproduced experimentally in 1:100 reduced scale. This experiment was FE modeled to evaluate the performance of the aforementioned failure criteria. The results verified the significant influence of the strain rate and stress state on the failure strain. In addition, it is shown that the sole use of tensile tests is not enough to properly characterize the material failure observed in the structural collapse mode of the miniature ship bottom structure. This collapse is shown to be a combination of stretching and tearing of structural members.

Identification of the mechanisms responsible for static strain ageing in heavily drawn pearlitic steel wires

The microstructural changes occurring during drawing and ageing in pearlitic steel wires have been studied using the thermoelectric power (TEP) measurements combined with atom probe tomography (APT) and differential scanning calorimetry (DSC). APT analysis confirmed that cementite dissolution occurs during the cold-drawing process. The high sensitivity of TEP to solute atoms allowed two ageing mechanisms to be identified, both related to a redistribution of carbon atoms. The complementary use of tensile tests and DSC confirmed these results.

Cyanoacrylate Tissue Adhesives – Effective Securement Technique for Intravascular Catheters: In Vitro Testing of Safety and Feasibility

Partial or complete dislodgement of intravascular catheters remains a significant problem in hospitals despite current securement methods. Cyanoacrylate tissue adhesives (TA) are used to close skin wounds as an alternative to sutures. These adhesives have high mechanical strength and can remain in situ for several days. This study investigated in vitro use of TAs in securing intravascular catheters (IVC). We compared two adhesives for interaction with IVC material, comparing skin glues with current securement methods in terms of their ability to prevent IVC dislodgement and inhibit microbial growth. Two TAs (Dermabond, Ethicon Inc. and Histoacryl, B. Braun) and three removal agents (Remove™, paraffin and acetone) were tested for interaction with IVC material by use of tensile testing. TAs were also compared against two polyurethane (standard and bordered) dressings (Tegaderm™ 1624 and 1633, 3M Australia Pty Ltd) and an external stabilisation device (Statlock, Bard Medical, Covington) against control (unsecured IVCs) for ability to prevent pull-out of 16 G peripheral IVCs from newborn fresh porcine skin. Agar media containing pH-sensitive dye was used to assess antimicrobial properties of TAs and polyurethane dressings to inhibit growth of Staphylococcus aureus and Staphylococcus epidermidis. Neither TA weakened the IVCs (P >0.05). Of removal agents, only acetone was associated with a significant decrease in IVC strength (P <0.05). Both TAs and Statlock significantly increased the pull-out force (P <0.01). TA was quick and easy to apply to IVCs, with no irritation or skin damage noted on removal and no bacterial colony growth under either TA.

Oat hull composites from conjugated natural oils

Oat hull composites have been prepared by the free radical polymerization of regular or modified natural oils with divinylbenzene, n-butyl methacrylate, and maleic anhydride in the presence of dried, ground oat hulls. Parameters, such as cure time, filler load, cure temperature, and the fatty acid composition of the conjugated natural oil, have been investigated and related to the structure and properties of the composites. Structure–property relationships have been determined with the use of tensile tests, DMA, TGA, and Soxhlet extraction, followed by 1H NMR spectroscopic analysis of composite extracts. The best overall properties have been obtained for tung oil-based composites bearing 80 wt% of oat hulls cured at 160 °C for 4 hours.

Carbon nanotube yarn and 3-D braid composites. Part I: Tensile testing and mechanical properties analysis

Macroscopic textile preforms were produced with a multi-level hierarchical carbon nanotube (CNT) structure: nanotubes, bundles, spun single yarns, plied yarns and 3-D braids. The 3-D braided preform was the first of its kind produced by textile processing technique and used as a composite reinforcement consisting solely of carbon nanotubes. Four different epoxy systems that possessed a wide range of mechanical properties (owed to an added modifier) were infused into the CNT yarns and 3-D braids. Mechanical characterization of the resulting composites was conducted through the use of tensile testing. It was found that the tensile strength, stiffness and, especially, strain-to-failure values for each preform type were close regardless of the properties of the matrix whose strain-to-failure values ranged from 3.6% to 89%. This is hypothetically attributed to the nano-scale interaction between individual nanotubes and polymeric macromolecules in the composites. This hypothesis is validated by the Dynamic Mechanical Analysis results in Part II.

Robustness study on the behaviour of top-hat thin-walled high-strength steel sections subjected to axial crushing

Abstract A robustness study on the behaviour of top-hat thin-walled high-strength steel sections from different batches subjected to dynamic axial crushing has been performed. The robustness was investigated by considering 25 components produced from five different material batches. The variation of material properties within and between the batches was characterised by use of tensile tests. A 3D scanner was used in order to study the geometric imperfections of the profiles. The components were crushed in a kicking machine at an impact velocity of 10 m/s with an impacting mass of 985 kg. Fracture was observed in all the components, but the extent of fracture varied from batch to batch and seemed to be positively correlated to the material strength and negatively correlated to the material ductility. The mean force varied significantly within each batch, while the variation in the batch mean of the mean force was relatively small compared to the variations in the batch means of the material strength and thickness.

Molecular-dynamics of a 2D Model of the Shape Memory Effect

This work investigates the thermodynamic properties of a qualitative atomistic model for austenite–martensite transitions. The model, still in 2D, employs Lennard-Jones potentials for the determination of the atomic interactions. By use of two atom species it is possible to identify three stable lattice structures in 2D, interpreted as austenite and two variants of martensite. The model is described in the first part of the work [6] in detail. The present work studies the thermodynamic properties of the model concerning a small, 2-dimensional test assembly consisting of 41 atoms. The phase stability is investigated by exploitation of the condition of minimal free energy. The free energy is calculated from the thermal equation of state, which is measured in numerical tensile tests. In the second part of this work a chain of eleven 41-atom assemblies is investigated. The chain is interpreted as an idealized larger body, where the individual crystallites represent crystallographic layers allowing for the creation of micro structure. By use of tensile tests at various temperature conditions we sketch how such chain may exhibit quasi-plasticity, pseudo-elasticity and the shape memory effect.

Superplastic deformation behavior of the electrocodeposited Ni/SiC composite

The superplasticity of Ni/SiC composite produced by electrodeposition was characterized for the first time through the use of tensile tests. A maximum elongation of 571% was obtained at a temperature of 703 K and a strain rate of 8.33 × 10 −4 s −1. Fracture surfaces and microstructures were studied using SEM and TEM.

Stress-relaxation testing. Part II: Comparison of bending profiles, microstructures, microhardnesses, and surface characteristics of several wrought wires

1 h d 1 l’t t e enta I era ure fails to provide the profession with a thorough understanding of the wrought wires used as clasp materials in dentistry. All information currently available has largely been obtained through the use of tensile testing. In tensile testing, the atoms within the alloy are subjected to tensile stresses at a constant rate of loading. This is not representative of the type of stress present in clasp arms during clinical use. Since clasp arms are required to undergo repeated bending, both tensile and compressive stresses are developed within the material. The extent and rate of any clasp deflection vary. To provide data which can be analyzed to obtain results which can be applied to clinical situations, it is imperative that the test methods approach the conditions present during clinical function as much as possible. During stress-relaxation testing, the test specimen is deflected by the instrument and released. The resiliency of the material returns the test specimen to its original position in the same manner as a clasp arm, after it has passed beyond the curvature of the tooth. As the clasp is deflected, both the tensile and compressive stresses

The use of tensile tests to determine the optimum conditions for butt welding polyethylene pipes of different melt flow index

The butt fusion welding of four different grades of polyethylene pipe has been studied and the feasibility of producing good welds between pipes of different melt flow index has been examined. Weld quality has been assessed on the basis of tensile tests and microstructural studies. The factors influencing the microstructure are discussed; in particular, the flow of molten polymer within the welds.

The use of tensile tests to determine the optimum conditions for butt fusion welding certain grades of polyethylene, polybutene-1 and polypropylene pipes

The optimum conditions for butt fusion welding certain grades of polyethylene, polybutene-1 and polypropylene pipes have been determined on the basis of tensile test results. The effect of the welding bead has been discussed and the conclusion reached that removal of the welding beads enables a clearer picture to be obtained of weld performance when this is judged from a tensile test. An examination of the microstructures of each weld has shown the presence of different zones. The importance of these zones is discussed in relation to the short- and long-term strength of the welds.