Tensile Test Method Research Articles

STUDI EKSPERIMENTAL PENGARUH PROSES PEMBAKARAN TERHADAP SIFAT MEKANIS PADA BAJA TULANGAN

Reinforcing steel is a very important material contained in the concrete, where it has a function as a tensile load receiver where the concrete is very weak in receiving the tensile load. In the event of concrete and reinforced concrete fires can be complementary because the reinforcing steel can accept tensile load while the concrete can accept the press load. The method of testing conducted in this study using the method of tensile testing, metallography, and composition testing. Where prior to testing the reinforcing steel is first casted in the concrete after it is done combustion process with a temperature of 400 ° C, 600 ° C, 800 ° C and cooled with water and air cooling medium. After done all the testing process got result that is reinforcing steel which has the most optimal tensile stress occurred at temperature of 600 ° C with water cooling media which got value of tensile strength equal to 596,46 N / mm2. Keywords: : Reinforcing Steel, Tensile Test

Understanding Curly Hair Mechanics: Fiber Strength

The relationship between the geometric and mechanical profiles of hair fibers has been studied, with special focus on curly samples. Incidental observations pointed to a significantly different viscoelastic character with varying curliness. Further investigations confirmed initial observations, showing an initial distinct toe region behavior for curly fibers on the stress-strain plot, which is absent for straight fibers. This behavior suggested a difference in the viscoelastic nature of the curly fiber that is linked to mechanical energy stored in the fiber. Results also suggest that the strength of hair depends on two main components, and further pointed out that de facto methods of tensile testing may erode curly fiber strength during preparation. The main outcome of this study is that the tensile strength (σT) of hair fibers is composed of two (rather than one main) components, namely the toe region (σt) and the elastic region (σε), so that: σT=σt+σε. For noncurly fibers, the greatest part of fiber strength is derived from σε, while σt ≈ 0. For curly fibers, σt (i.e., springiness) adds significantly to the overall strength, even though σε remains the major contributor. Although these results require validation in larger studies, they are significant in the current understanding of curly hair. Also, they may represent a fundamental shift from the current understanding of tensile testing of human hair in general.

Hot tensile test for determining the material constant on superplastic 5083Al alloy sheet

Abstract The superplastic alloys are characterized by strain rate sensitivity index (m). Actual values of m depend on temperature, strain rate and grain size. This experiment aims to attain maximum formability by superplastic forming processes in AA 5083 alloy using uniaxial hot tensile test method. To optimize the different material parameters such as maximum elongation, yield stress, temperature, strain rate and strain rate sensitivity index with the help of the uniaxial hot tensile method. An experimental and Finite Element method are adopted, to attain the permeability by achieving the material properties, at various temperatures and various initial strain rate conditions.

Mapping the spatial variation of mitral valve elastic properties using air-pulse optical coherence elastography

The mitral valve is a highly heterogeneous tissue composed of two leaflets, anterior and posterior, whose unique composition and regional differences in material properties are essential to overall valve function. While mitral valve mechanics have been studied for many decades, traditional testing methods limit the spatial resolution of measurements and can be destructive. Optical coherence elastography (OCE) is an emerging method for measuring viscoelastic properties of tissues in a noninvasive, nondestructive manner. In this study, we employed air-pulse OCE to measure the spatial variation in mitral valve elastic properties with micro-scale resolution at 1 mm increments along the radial length of the leaflets. We analyzed differences between the leaflets, as well as between regions of the valve. We found that the anterior leaflet has a higher elastic wave velocity, which is reported as a surrogate for stiffness, than the posterior leaflet, most notably at the annular edge of the sample. In addition, we found a spatial elastic gradient in the anterior leaflet, where the annular edge was found to have a greater elastic wave velocity than the free edge. This gradient was less pronounced in the posterior leaflet. These patterns were confirmed using established uniaxial tensile testing methods. Overall, the anterior leaflet was stiffer and had greater heterogeneity in its mechanical properties than the posterior leaflet. This study measures differences between the two mitral leaflets with greater resolution than previously feasible and demonstrates a method that may be suitable for assessing valve mechanics following repair or during the engineering of synthetic valve replacements.

Flexible polypyrrole-coated conductive fabric sensor for large deformation measurement

PurposeStrain sensors have been widely used to measure the strain of the structure. However, the ordinary sensing elements are not suitable for measuring large deformation on an irregular surface, which limits their applications. Recently, flexible sensors have attracted extensive interest because they can overcome the shortage of the ordinary sensing elements. The paper aims to discuss this issue.Design/methodology/approachIn this paper, the whole measurement process of strain sensing behavior and the dimension design of fle3xible strain sensing system use the macroscopic measurement method of material tensile test to accurately measure the resistance change with strain. Afterwards, combining electrical components, the flexible strain sensors are produced for two biomedical applications: the wearable data-collecting gloves and rehabilitation training system.FindingsThe results show that the developed conductive fabric can exhibit high sensitivity, large workable strain range (>50 percent) under simple and repeated tension and good stability. Both applications demonstrate that the polypyrrole-coated fabric sensor can successfully measure the large and repeat strain, capture the motion of body and display corresponding information almost in real time.Originality/valueThe limitation lies in the lack of a holistic strain sensing mechanism study, and the lack of a corresponding theoretical model to explain the experimental results.

Разработка многослойного упаковочного материала на основе полиолефиновых смесей, модифицированных сополимером этилена с пропиленом, для хранения пищевых продуктов

The research features a comprehensive study aimed at increasing the technological compatibility of multilayer packaging materials. The paper describes a recycling technology with the prospect of returning the resulting secondary raw materials to the production cycle. The research included the following tasks: to conduct a comprehensive study of polyolefin mixtures modified by ethylene propylene copolymer; to study the effect of the copolymer on the rheological and physicomechanical properties of polymer compositions; to propose a technology for the recycling of secondary polyolefin mixtures. The research involved the following methods: the capillary viscometry method was used to determine the rheological properties of polymer compositions; the tensile test method was employed to define the physicomechanical properties of the compositions; the pycnometric method was used to assess the density of the mixtures. The study featured such polymers as polyethylene, polypropylene, and ethylene-propylene copolymer, which was chosen as a link between the polymers. The authors obtained polymer compositions in various ratios of polyethylene, polypropylene, and ethylene-propylene copolymer: 70:30:0; 68.5:28.5:3; 65:25:10; 30:70:0; 28.5: 68.5: 3; 25:65:10. The article describes the process of modifying polyolefin compositions based on polyethylene and polypropylene by ethylene-propylene copolymer on a single-screw extruder. The authors defined the rheological properties and the deformation-strength characteristics of the polymer mixtures. Repeated processing proved to lead to a decrease in the physicomechanical properties of polyolefin mixtures, with the exception of compositions based on polyethylene and polypropylene in the ratio of 30:70, where the breaking stress increased. The number of processing cycles increased the melt flow rate of the mixtures. The proposed technology is meant for producing multilayer packaging materials using packaging waste in the middle layer for contact with food.

Hydrogen embrittlement of a microalloyed bainitic forging steel

The hydrogen embrittlement (HE) of a novel microalloyed bainitic forging steel with a strength level of 1100 MPa was evaluated using electrochemical charging and slow strain rate tensile test method with notched round bar specimens. The results show that the susceptibility to HE of the as-forged bainitic forging steel is notably higher than that of the quenched and tempered (Q&T) steel at same strength level, which is ascribed primarily to the presence of a relatively high amount of large blocky martensite/austenite (M/A) constituents of the former. It was found that low-temperature tempering treatment at 200 °C could significantly alleviate the susceptibility to HE by a relative decrease of ~ 35% of the as-forged bainitic forging steel at no expense of strength and ductility, though its resistance to HE is still a little lower than that of the Q&T steel. Thus, it is suggested that efforts concerning refining of the large blocky M/A through optimizing chemical composition and processing route could help to further alleviate the susceptibility to HE of the tested bainitic forging steel.

Experimental and numerical study of hydro-mechanical deep drawing of 2024 aluminum alloy sheet at elevated temperatures

In the present study, hydro-mechanical deep drawing (HDD) of 2024 aluminum alloy sheet was investigated using the experimental tests and numerical simulations. The experimental tests were done at elevated temperature by considering four heating elements in the fluid chamber of HDD die which provided four temperatures of 25 °C (room temperature), 60 °C, 100 °C, and 140 °C for the HDD process. The effect of fluid chamber pressure was studied on the formability of AA 2024 by considering four pressures of 6, 10, 14 and 18 bar. The numerical simulations of the ABAQUS/Explicit and the Gurson-Tvergaard Needleman (GTN) damage model was used for fracture prediction of AA2024 in the HDD at room temperature. The anti-inference method and numerical simulation of the uniaxial tensile test of AA2024 sheet was used for identification of the GTN parameters. The experimental and numerical results indicated that the formability and forming height of AA2024 increased in the HDD by increasing of the pressure and temperature of the fluid chamber.

Parametric Investigation of Squeeze Casting Process on the Microstructure Characteristics and Mechanical Properties of A390 Aluminum Alloy

Effects of squeeze casting (SQC) parameters, including squeezing pressure, superheats of liquid metal and die preheating temperature on microstructure characteristics and mechanical properties of A390 aluminum alloy, were evaluated using L9 design based on Taguchi method. Squeeze casting was performed by a 25-ton hydraulic press, and all of the parameters were evaluated at 3 different levels: the squeezing pressure was at 60, 90 and 120 MPa, the superheat of the liquid metal was at 50, 100 and 150 °C and the die preheating temperature was at 200, 250 and 300 °C. The microstructure characterization was also performed using optical microscopy image analysis and scanning electron microscope (SEM). Tensile and Brinell test methods were applied for measuring ultimate tensile strength, yield strength, elongation and hardness. The results showed that the SQC process modified cast microstructure and improved mechanical properties of the alloy. In addition, the variations of the SQC parameters, specially the squeezing pressure, have significant effects on the size and volume fractions of the primary silicon, eutectic cells and the mechanical properties. According to the results, increase in squeezing pressure from 60 to 120 MPa within the tested range leads to primary silicon area decrease by 48% and silicon eutectic decrease by 44.4%; however, applied pressure did not have any significant effects on morphology of phases. On the other hand, superheating over 100 °C and die preheating at 200 °C had significant effects on the final result. It is clearly observed that rising pressure to 90 MPa consequently increases the tensile strength, elongation and hardness. But increasing the pressure to over 90 MPa did not have any significant effects on the final result.

Preparation and properties of rubber nanocomposites based on NR/NBR blend reinforced with nanosilica and carbon black

AbstractRubber nanocomposites based on natural rubber (NR)‐butadiene nitrile rubber (NBR) blend filled with silane modified nanosilica (NSBT) and carbon black (CB) were prepared by melt mixing method by using an internal mixer. The effect of CB and NSBT on thermo‐mechanical properties of the materials was investigated by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dynamic‐mechanical analysis (DMA) and tensile testing method. The results show that the NR/NBR blends reinforced with both CB and NSBT possess the properties much better than that reinforced with only CB or NSBT. With the CB/NSBT ratio of 25/5, the properties of the NR/NBR blends were remarkably enhanced, especially the increase in tensile strength by about 64 % and the increase in the thermal stability by about 13°C. The reasons for the improvement of NR/NBR blends’ properties are due to better compatibility of the components in the rubber blend as well as the better compactness in their structure with the presence of NSBT.

Time Dependent Structure and Property Evolution in Fibres during Continuous Carbon Fibre Manufacturing.

Here we report on how residence time influences the evolution of the structure and properties through each stage of the carbon fibre manufacturing process. The chemical structural transformations and density variations in stabilized fibres were monitored by Fourier Transform Infrared Spectroscopy and density column studies. The microstructural evolution and property variation in subsequent carbon fibres were studied by X-ray diffraction and monofilament tensile testing methods, which indicated that the fibres thermally stabilized at longer residence times showed higher degrees of structural conversion and attained higher densities. Overall, the density of stabilized fibres was maintained in the optimal range of 1.33 to 1.37 g/cm3. Interestingly, carbon fibres manufactured from higher density stabilized fibres possessed lower apparent crystallite size (1.599 nm). Moreover, the tensile strength of carbon fibres obtained from stabilized fibres at the high end of the observed range (density: 1.37 g/cm3) was at least 20% higher than the carbon fibres manufactured from low density (1.33 g/cm3) stabilized fibres. Conversely, the tensile modulus of carbon fibres produced from low density stabilized fibres was at least 17 GPa higher than those from high density stabilized fibres. Finally, it was shown that there is potential to customize the required properties of resultant carbon fibres suiting specific applications via careful control of residence time during the stabilization stage.

Experimental evaluation of tensile strength test methods for steel fibre-reinforced concrete

This study presents an experimental evaluation of three different methods for determining the tensile strength of steel fibre reinforced concrete (SFRC). The test methods include the splitting test (ST), double punch test (DPT) and direct tensile test (DTT). The compressive strength of the concrete used in this study ranged between 30 and 80 MPa with 0%, 1·5% and 3% steel fibre by volume of the concrete. In total, 81 concrete cylinders were cast and tested for 28-d compressive strength, splitting tensile strength and double punch tensile strength of the concrete. In addition, 27 concrete prism specimens were cast and tested to determine the direct tensile strength of the concrete. The test results show that, compared to the ST, the DPT is more effective in predicting the tensile strength of SFRC, as the tensile strengths obtained from the DPT and the direct tensile test are very close. The DPT is easier to perform and costs less than the ST and the DTT.

Comparison of Adhesive Properties of Polyurethane Adhesive System and Wood-plastic Composites with Different Polymers after Mechanical, Chemical and Physical Surface Treatment.

The cost of most primary materials is increasing, therefore, finding innovative solutions for the re-use of residual waste has become a topic discussed more intensely in recent years. WPCs certainly meet some of these demands. The presented study is focused on an experimental analysis of the effect of surface treatment on the adhesive properties of selected WPCs. Bonding of polymer-based materials is a rather complicated phenomenon and modification of the bonded area in order to improve the adhesive properties is required. Two traditional types of surface treatments and one entirely new approach have been used: mechanical with sandpaper, chemical with 10 wt % NaOH solution and physical modification of the surface by means of a MHSDBD plasma source. For comparison purposes, two high-density polyethylene based products and one polyvinyl-chloride based product with different component ratios were tested. A bonded joint was made using a moisture-curing permanently elastic one-component polyurethane pre-polymer adhesive. Standardized tensile and shear test methods were performed after surface treatment. All tested surface treatments resulted in an improvement of adhesive properties and an increase in bond strength, however, the MHSDBD plasma treatment was proven to be a more suitable surface modification for all selected WPCs.

A novel acoustic emission monitoring method of cross-section precise localization of defects and wire breaking of parallel wire bundle

The monitoring and localization of defects and wire breaking of bridge cable are vital to the safe operation of the whole bridge. In this work, an innovative monitoring method that uses waveguides to draw out the steel wires at the end of the cable is proposed. This monitoring method can effectively capture the acoustic emission (AE) signal produced by defects and wire breaking of the cable. The transverse position of the wire breaking can also be accurately located so as to provide basis for the decision making of maintenance department. The pencil-lead breaks (PLB) test method is utilized to investigate the influence of the transition modes between the waveguide and the sensor and the connection modes between the waveguide and the cone on the AE signal. The PLB test and tensile test method are utilized to examine the AE signal characteristics of different sensors at the end of steel wires. Results showed that the cone transition between the waveguide and the sensor and the welding connection between waveguide and cone exhibit the minimum effect on AE waveform and parameters, such as amplitude, compared with that of the reference sensor without waveguide. In the tensile test, the transverse position of the wire breaking cannot be identified by analyzing the AE signals collected by each senor when the wire breaks, whereas it can be identified in the process of defects before the wire breaks.

A New Method for Direct Tensile Testing of Concrete

Abstract Different testing methods were used in previous studies to measure the direct tensile strength of concrete. However, these methods experienced several major deficiencies such as stress concentration at the end of the specimens because of inadequate gripping and loading eccentricity and nonuniform fracture plane because of difficulties in aligning and centering the specimens during testing. This study presents the details of a new method of testing concrete under uniaxial tension. The method was developed to overcome the difficulties associated with testing methods adopted in the previous research studies. A full description of the wooden molds used in casting the specimens and the loading arrangements including the end grips, universal joints, and frame in which the specimens were tested under uniaxial tension are presented. As expected, all the tested specimens were fractured at the middle where the cross-sectional area was reduced by 20 %. Also, no crushing failure or slippage was observed at the ends of the tested specimens.

Influence of cooling rate and additives on low-temperature properties of asphalt mixtures in the TSRST

The paper presents the results and analysis of low-temperature properties of asphalt mixtures according to Thermal Stress Restrained Specimen Test (TSRST) and Indirect Tensile Test methods. Different groups of bitumen were investigated: neat, SBS-modified and highly SBS-modified. Influence of cooling rates (1 °C/h, 3 °C/h, 5 °C/h and 10 °C/h) and additives (aramid fibres and crumb rubber) was identified as well. Moreover, for each factor stiffness moduli were back-calculated from the TSRST results and analysed. The greatest impact on the TSRST results had type of bitumen, followed by the cooling rate and additives. Application of longer fibres improved low-temperature properties of the asphalt mixtures.

Tensile properties of CFRP manufactured by resin transfer molding considering stacking sequences at various strain rates

This paper is concerned with the improvement of a tensile test method and the material properties of carbon fiber reinforced polymer manufactured by resin transfer molding considering stacking sequences at various strain rates for auto-body. Auto-body structure experiences the strain rates up to several hundreds per second during car crash. In order to apply the carbon fiber reinforced polymer panel into auto-body structures, it is critical to acquire the material properties of carbon fiber reinforced polymer at various strain rates considering stacking sequences. The tensile test method is improved for acceptable test results. Test specimens are modified for high-speed tensile tests of carbon fiber reinforced polymer in order to achieve designated strain rates and eliminate the effect from unfavorable conditions of inhomogeneity of deformation. Various types of grip tab materials are employed for acceptable failure modes. Tensile tests have been carried out with non-crimp fabric made by 50K high strength carbon fiber (NCF) and woven fabric made by a 2/2 twill pattern of 3K high strength carbon fiber (TWILL) with different stacking sequences of 0° and 90° unidirectional cases as well as [0°/90°] and [45°/−45°] symmetric cases. Digital image correlation method and force equilibrium grid method are adopted for strain and stress measurement of a carbon fiber reinforced polymer specimen during a tensile test. The material properties acquired indicate that the carbon fiber has little rate dependency, while the epoxy matrix has remarkable rate hardening at strain rates from 0.001 s−1 to 100 s−1.

Adhesive strength in a high voltage mica insulation system

The problem of maintaining a monolithic high-voltage mica insulation made by the Resin Rich technology for windings of electrical machines and conductors is considered. The violation of solidity like delaminations and peeling off from conductor can happen both during the process of manufacturing and during exploitation of constructions. The possibility of breaking the solidity is directly related to the magnitude of adhesion strength. Design and manufacturing technology of samples in laboratory and industrial conditions to determine the adhesion strength were developed. Adhesive strength is determined by the method of shear and tensile test method between insulation layers and in system of metal- mica insulation.The created method for the manufacture of samples made it possible to test samples with various designs of adhesive contact, materials of adhesive contact and technological parameters of the pressing process. The adhesion strength depends on the parameters of the thermal pressing process and the degree of curing of the binder in the initial resin rich tape. Adhesive contact of mica insulation to metal through fiberglass is more durable than through film

Development of a biaxial tensile testing machine for pulsed neutron experiments

A biaxial tensile testing method has been used to get macroscopic information on elastoplastic deformation of a thin steel specimen and improve the accuracy of plastic processing of steel materials. We newly developed a biaxial tensile testing machine for pulsed neutron experiments (BTM-NEU) to provide the microscopic crystallographic information of steel materials under biaxial load and correlate it with the macroscopic mechanical properties of the materials. The performance of the BTM-NEU was experimentally evaluated with cold-rolled mild steel and hot-rolled high-tensile-strength steel materials and compared with that of a standard biaxial tensile testing machine (BTM-std) as follows.•The BTM-NEU can test an ISO-standardized cruciform specimen as the BTM-std and its performance is equivalent to that of the BTM-std.•The BTM-NEU has excellent long-time reliability and stability necessary for pulsed neutron experiments, especially Bragg-edge neutron imaging experiments.•The BTM-NEU can be applied to pulsed neutron experiments using a Bragg-edge imaging method.

Applicability of shear punch testing to the evaluation of hot tensile deformation parameters and constitutive analyses

Shear punch testing (SPT) was used to evaluate hot deformation constitutive parameters, and the results were compared with those of the conventional uniaxial tensile testing (UTT) method. Both tests were performed on a rolled Sn–5Sb alloy, as a model material, in the temperature range of 298–400K and under strain rates in the range of 5×10–4 to 1×10–2s–1. Reasonable agreement was found between the parameters obtained in both deformation modes for the power-law, exponential, and hyperbolic sine constitutive equations. The obtained stress exponents and activation energy values in shear deformation were almost the same as those found in the tensile deformation. Therefore, it can be concluded that the data provided by the easy-to-perform SPT can be used for the prediction of constitutive equations as well as deformation mechanisms of the material in the tensile deformation mode. Based on the power-law stress exponents in the range of 4.5–7.0 and activation energy values of about 54–59kJmol–1, dislocation climb mechanism controlled by the lattice diffusion could be suggested as the main controlling mechanism of the deformation of the alloy in both deformation modes.