Tensile Strength Of Samples Research Articles

Experimental study on hole quality and tensile progressive failure following fiber laser cutting of multidirectional carbon fiber reinforced plastic laminates

Fiber laser was feasible to cut carbon fiber reinforced plastic (CFRP) laminate with high efficiency and particularly meet short cycle time in large-volume vehicle production. Large differences in physical and thermal properties between fiber and resin, however, have been prohibiting the application of fiber laser cutting on CFRP composites. Joining of CFRP parts is mainly dependent on mechanical bolting/riveting, which depends critically on the quality of processed holes. In this study, CFRP laminates used for manufacturing new energy vehicles were employed to investigate the hole quality during fiber laser cutting in continuous wave and pulse modes. Statistical analysis was performed to optimize process parameters to minimize heat affected zone (HAZ) levels. Results indicated that thermal defects including matrix recessing/decomposition and protruding and uncut fibers were prevalent at hole entry and exit irrespective of processing parameters. Low level of laser power (800 W) and linear energy (50 J/mm) together with the pulse mode were preferred to minimize HAZ during fiber laser cutting of CFRP laminates, while the effect of a laser mode was negligible. Tensile strength of samples with open hole (6.0 mm diameter) cut by a fiber laser varied from 131 to 143 MPa, which depended to some extent on HAZ levels. Massive delamination, fiber breakage, and splitting bounds were the main damage/failure modes.

Study on microstructure and composition segregation of laser welded joints of 2A14 aluminum alloy

Laser welding is an attractive welding process for aluminum alloys, because its low heat input minimizes the width of fusion zone (FZ) and heat affected zone (HAZ). The present research is mainly concerned with the effect of welding parameters on microstructure morphology, composition segregation microhardness and tensile test of laser welding of 2 mm thickness 2A14 aluminum alloy. The results show that the welded joint with good quality can be achieved when the laser power is 2.5 kW and the welding speed is 2.4 m min−1. The center of the weld seam exhibits fine equiaxed grains, while the FZ consists of coarse columnar crystals and Cu segregates at the boundary of the columnar crystals. And the tensile strength of sample 4 is 274.3 MPa and about 74.4% of that of BM, which is higher than that of 3 samples. In addition, the welding speed has greater influence than the laser power on the microhardness of the joints.

Interfacial Shear, Tensile Strength and Young Modulus of Kenaf Fiber: The Effects from Different Settings of Alkali Treatment

The project explained about what happened to fiber matrix interfacial shear strength, fiber tensile strength and fiber Young modulus when different alkali treatment settings were applied. Kenaf fiber were exposed to different alkali concentration, immersion duration and immersion temperature. To determine the interfacial shear strength (IFSS), unsaturated polyester matrix was utilised to expose the properties. The effects of alkali treatment on sample mechanical properties were successfully evaluated, whereby the treated sample's IFSS showed slightly higher value compared to untreated kenaf fiber at all settings. Meanwhile, the IFSS value was increased at low alkali concentration and decreased with the increment of alkali concentration percentage. On the other hand, untreated kenaf fiber tensile strength and Young modulus average value was 632MPa and 40.65GPa respectively. It was also established that the sample's tensile strength was keep reducing after treatment at all settings. At 30 minutes constant immersion duration, the percentage of kenaf fiber tensile strength decrement was 42.57% when other treatment settings increased. Furthermore, a decline pattern was obtained in term of sample tensile strength and Young modulus when the alkali treatment increased at all settings.

Rheo-Diecasting of Wrought Magnesium AZ31 Alloy and the Effect of Injection Velocity on Microstructure and Tensile Strength

Wrought Mg AZ31 alloy was near-net-shaped by semisolid rheo-diecasting. Parts with 42% and 61% solid fraction were produced at different injection velocities. The impact of injection velocity on the microstructure and the tensile strength of samples have been investigated. Results indicated that the shape factor and the particle size of primary α-Mg in the microstructure decreased with the increase of injection velocity, and the morphology of both secondary α-Mg and eutectic α-Mg + Mg17Al12 mixture were refined with the increase of injection velocity. The surface liquid segregation in the sample closely relates to the injection velocity and the solid fraction of slurries, and it decreased with the increase of injection velocity and the decrease of the solid fraction. Cold shut, crack, and gas porosity were the main internal defects that rely on the injection velocity. The tensile strength of the samples decreased with the increase of injection velocity, and the best value of 201 and 192 MPa was obtained at 0.5 m/s and 1 m/s for the sample with the solid fraction of 0.61 and 0.42, respectively. This work demonstrated a predominant effect of internal defects on the property of the rheo-diecasting (RDC) product than the microstructure; thus, defect reduction should be preferentially considered in the optimization of the RDC process.

Microstructure evolution and mechanical properties of 316L austenitic stainless steel with aluminum addition by warm rolling

Microstructure evolution and mechanical properties of 316L austenitic stainless steel with aluminum addition by warm rolling at 550 °C were investigated. It is found that sample is composed of an ashen austenite matrix, a gray black ferrite phase and a small number of NiCx. The average grain sizes are 21.62, 19.66 and 19.49 μm for samples with the rolling deformation of 30%, 50% and 70%, respectively. The yield strength and tensile strength of samples with solid solution time of 30 min and deformation of 70% are higher. The fracture modes are similar and belong to toughness fracture. The fracture surfaces of the samples are composed of relatively large equal-axis ductile dimples (5–15 μm) and fine scattered ones around the dimples ( orientation is more prominent. {001} rotation-cube textures are present in ferrite phase of samples and weak Goss texture is formed in austenite pole images.

Characteristics of Electrical Heating Elements Coated with Graphene Nanocomposite on Polyester Fabric: Effect of Different Graphene Contents and Annealing Temperatures

This paper reports the fabrication of electrical heating elements based on the graphene/waterborne polyurethane (WPU) composite coated on polyester fabric with toughness like that of artificial leather. Samples were prepared with 0, 4, 8, and 16 wt% of graphene by using the knife edge method, and then, the samples were annealed from 100 oC to 160 °C. The graphene content had a large effect on the electrical and electrical heating properties. The surface resistivity was decreased by approximately 6 orders of magnitude with an increase from 0 wt% to 16 wt% graphene/WPU composite fabric. The electric heating properties were also improved, as indicated by the percolation threshold. Samples with various graphene contents were annealed, and it was found that the electrical and electrical heating properties were improved, and the most enhanced properties were obtained when the samples were annealed at 120 °C. The initial modulus and tensile strength were increased in comparison with those of 0 wt% and 16 wt% graphene/WPU composite coated on fabrics, but the elongation at break value was slightly decreased with an increasing graphene content. When the samples were annealed, initial modulus and tensile strength of samples were improved at 120 °C and 140 °C, and they were slightly decreased at 160 °C. However, the elongation at break showed an opposite tendency to the tensile strength. With the increase in content of graphene and annealing at 120 °C and 140 °C, the samples were more stiff and tough, and at 160 °C, the samples were softer. Therefore, graphene/WPU composite coated on polyester fabric by use of the annealing process may have applications in electrical heating elements due to its excellent heating performance and toughness like that of artificial leather.

The effect of liquid nitrogen cooling on coal cracking and mechanical properties

Liquid nitrogen is a type of super-cryogenic fluid, which can cause the reservoir temperature to decrease significantly and thereby induce formation rock damage and cracking when it is injected into the wellbore as fracturing fluid. An experimental set-up was designed to monitor the acoustic emission signals of coal during its contact with cryogenic liquid nitrogen. Ultrasonic and tensile strength tests were then performed to investigate the effect of liquid nitrogen cooling on coal cracking and the changes in mechanical properties thereof. The results showed that acoustic emission phenomena occurred immediately as the coal sample came into contact with liquid nitrogen. This indicated that evident damage and cracking were induced by liquid nitrogen cooling. During liquid nitrogen injection, the ring-down count rate was high, and the cumulative ring-down counts also increased rapidly. Both the ring-down count rate and the cumulative ring-down counts during liquid nitrogen injection were much greater than those in the post-injection period. Liquid nitrogen cooling caused the micro-fissures inside the coal to expand, leading to a decrease in wave velocity and the deterioration in mechanical strength. The wave velocity, which was measured as soon as the sample was removed from the liquid nitrogen (i.e. the wave velocity was recorded in the cooling state), decreased by 14.46% on average. As the cryogenic samples recovered to room temperature, this value increased to 18.69%. In tensile strength tests, the tensile strengths of samples in cooling and cool-treated states were (on average) 17.39 and 31.43% less than those in initial state. These indicated that both during the cooling and heating processes, damage and cracking were generated within these coal samples, resulting in the acoustic emission phenomenon as well as the decrease in wave velocity and tensile strength.

The Effect of Loading Frequency on Fatigue Life of Green onyx under Fully Reversed Loading

Rock structures, in reality, may be subjected to reversed tension-compression loading conditions due to blasting, earthquake, and traffic or injection-recovery process. In this case, loading frequency may have a great influence on fatigue life and behavior of rocks. The effect of loading frequency on fatigue life of a crystalline rock sample under fully reversed loading condition was examined. A new apparatus, based on the R. R. Moore fatigue test machine, was used to assess the fully reversed loading condition. The experimental tests were conducted with five sets of loading frequency and five levels of stress based on the ultimate tensile strength of samples. The test results showed that the variation of ultimate fatigue stress versus loading cycle number (S-N curve) of crystalline rock samples were in accordance with the observed results in other materials such as metals and ceramics. The results showed that fatigue life of a component is positively correlated with the frequency level. The fatigue life improves with increasing the loading frequency, but the improvement was more tangible at lower stress levels than at higher stress levels. The effect of loading frequency in an ordinary S-N equation was also formulated. The results also showed that the loading frequency does not influence the fatigue limit.

Effects of laser power on the microstructure and mechanical properties of 316L stainless steel prepared by selective laser melting

Selective laser melting (SLM) was used to prepare 316L stainless steel parts and the effects of laser power on the microstructure and mechanical properties of the final products were studied. With increasing applied laser power, the defects of as-built parts were reduced greatly and the as-built parts presented a highest relative density of 99.1%. The tensile strength of samples was significantly improved from 321 ± 10 MPa to 722 ± 10 MPa. The microhardness was homogeneous; the residual stresses in the samples were tensile, which were higher in the section perpendicular to the laser scanning strategy. The probable reasons for this phenomenon were proposed.

Investigation of the Ultrafine-Grained Structure Formation under Different Strain Rates

AbstractThe present paper deals with a study on formation of specific substructural features in OFHC copper processed by equal-channel angular pressing (ECAP) considering different strain rate conditions. Since two mechanical tensile testing equipments were being used, strain rate response could be studied in a wide range (both in static and dynamic regimes). Moreover, the copper before tensile testing was subjected to drawing and ECAP, separately, which allows to study the influence of both structural and substructural features (CG vs. UFG structure). Considering the static regime, it was found that UFG materials have advanced properties, showing higher strength and ductility in comparison to their CG counterparts. However, this is valid only to the critical value of the strain rate. In the dynamic regime, mathematical linearized results imply that ultimate tensile strength in samples processed by ECAP increases twice every 10 s−1rising, however, they lost approximately the same plastic properties than samples after drawing. Differences in the progress of mechanical properties are related to specific structural and substructural features evolved in the material during ECAP processing. Above mentioned features were studied in detail by methods of transmission and scanning electron microscopy (TEM, SEM).

Improved surface of additive manufactured products by coating

The additive manufactured coated sand products had obvious staircases on the surface and lots of small holes inside. The alcohol based refractory coating and the water based refractory coating were applied to improve the surface of the samples. The polygonal samples were used to check the effects of the coatings on reducing the surface roughness. The “8” shape samples were used to compare the effect of dipping time on the moisture content and the tensile strength of samples and the coating thickness. Results showed that the surface of samples could be improved by both alcohol based refractory and water based refractory coating. By the alcohol based refractory coating, the moisture content and the coating thickness increased and the tensile strength decreased with the dipping time obviously. By the water based refractory coating, the moisture content, the tensile strength of samples and the coating thickness kept approximately changeless with the increment of dipping time, which meant it could have enough time to dip to assure the coating’s quality on the surface of the samples. In conclusion, it was suitable to apply water based refractory coating and the dipping process to improve the surface of additive manufactured coated sand products.

Production of Paperboard Briquette Using Waste Paper and Sawdust

Nigeria has abundant supplies of biomass resources and agro-forestry residues (waste), including sawdust, whose potentials are yet to be fully utilized for economic advantage. This study was undertaken to investigate the properties of paperboard briquettes produced from a mixture of shredded waste paper (pulp) and sawdust using starch as binder. The paperboard briquettes were produced manually by compressing soaked mixtures of pulp and sawdust in a wooden mould (28 cm x 28 cm x 1 cm) with a compressive load of 26 kg in the mixing ratios (by weight) 100:0, 70:30, 50:50, 70:30, and 0:100 of pulp to sawdust, respectively. The compressed mixtures were sun dried for three days to ensure proper drying and free from moisture. Density, compressive and tensile tests were carried out on the test samples. The results showed that mass and density of the paperboard increased with increased amount of the sawdust in the mixture. Test results showed that compressive strength decreases as the sawdust content increases. Sample A, which is 100% paper, had a compressive strength of 5215 kPa, while Sample E, which is 100% sawdust, had a compressive strength of 22.02 kPa. It was also observed that sample B, which is 70% pulp and 30% sawdust, had the highest tensile strength of 0.629 kPa. However, the tensile strength reduces as the sawdust ratio in the mixture increases. The tensile strength of sample E (100% sawdust) could not be determined because the sample failed to bind properly. It was concluded that paperboard briquettes can be produced using paper and sawdust, which are generally considered wastes.

Properties of biomineralized (CaCO3) PVP-CMC hydrogel with reference to its cytotoxicity

ABSTRACTThe authors focus on properties of biomineralized (CaCO3) PVP-CMC hydrogel (designated as I–X) including cytotoxicity assay using primary mouse embryonic fibroblasts. The biomineralized samples (VII–X) showed >80% cell viability, was selected for further characterizations. FTIR and XRD indicate deposition of CaCO3 within the PVP-CMC hydrogel matrix, SEM shows changes in morphology and pore diameter (VII and VIII: 1–12 µm; IX: 10–70 µm; X: 70–170 µm), TGA determines the decomposition scenario of CaCO3, and tensile strength of samples (VII–X) ranged between 0.04 and 1.0 GPa, which practically corresponds to the modulus of cancellous bone.

Effects of Sesame Protein and Oil Pre-treatment on Preventing Damage of Bleached Hair

Hair treatment products help protect the hair cuticle resulting in high tensile strength and elasticity. The purpose of this study is to investigate the impact of sesame seed extracts containing proteins, oils and other nutrients on hair damage caused by hair bleaching procedures. The sesame seed powder was treated with an alkaline protease enzyme to make three samples: i) SP3 (sesame protein), ii) SO3 (sesame oil), and iii) SM3 (a mixture of protein and oil). The concentration of sesame proteins extracted using this enzymatic method was measured to be 97 mg/mL. Several physicochemical techniques were applied to analyze the effect of bleached hair before and after the treatment: i) thickness of hair, ii) tensile strength of hair, iii) surface changes of hair as measured using optical and electron microscopy, and iv) atomic force microscopy. The thickness of the SM3-treated sample was the highest among those tested here. The tensile strength of samples was shown to be SM3>SO3>SP3. Interestingly, following treatment with SM3, the tensile strength of hair increased 17.44%. Microscopy (electron, optical, and atomic force) observations were made to determine the state of the cuticle structure and determine which, if any treatments exhibit a damage-preventing effect. In summary, it is likely for sesame proteins and oils to be useful as a hair treatment agent to prevent hair damage. Specifically, sesame extracts will be a valuable ingredient for hair cosmetics in the future.

Effect of rolling temperature on the microstructure and mechanical properties of interstitial free steel

In the present research, to improve the mechanical of interstitial free steel, the hot rolling process has performed for 50% reduction in area at three different phase regions (below the lower critical point, above the upper critical point and intermediate region) of interstitial free steel. Samples were cooled down to room temperature by normal air cooling in the room temperature. The microstructure and mechanical properties of control rolled steel have been investigated by an optical microscope, Vickers hardness tester and tensile test. It has found that yield strength and ultimate tensile strength of sample rolled at a lower critical temperature (600°C) improved significantly without much significant change in ductility, due to ferrite grain refinement and an increase of dislocation density. Scanning electron microscope fractography analysis shows cup and cone fracture. Finally, it is suggested that a controlled rolling process of interstitial free steel in pure ferritic region conferred optimum properties.

Thermal, mechanical, and corrosion resistance properties of vinyl ester/clay nanocomposites for the matrix of carbon fiber‐reinforced composites exposed to electron beam

ABSTRACTVinyl ester/clay nanocomposites with 1, 3, and 5% nanoclay contents were prepared. X‐ray diffractography patterns and Scanning Electron micrographs showed that nanocomposites with the exfoliated structure were formed. Thermogravimetric analysis, water absorption test, and Tafel polarization method, respectively, revealed the improvements in thermal resistance, water barrier properties, and corrosion resistance properties of the samples with an increase in the amount of the incorporated nanoclay. Tensile tests showed that nanoclay also enhanced the mechanical properties of the polymer, so that the tensile strength of the samples with 5% nanoclay was more than 3 times higher than tensile strength of pure vinyl ester samples. Overall, the best properties were observed for the samples containing 5% nanoclay. Pure vinyl ester and nanocomposite with 5% nanoclay content were exposed to the electron beam radiation and their mechanical properties improved up to 500 kGy irradiation dose. Finally, pure vinyl ester and vinyl ester/nanoclay (5%) matrixes were reinforced with carbon fiber and the effect of electron beam irradiation on their mechanical properties was examined. The tensile strength and the modulus of the samples initially increased after exposure to the radiation doses up to 500 kGy and then a decrease was observed as the irradiation dose rose to 1000 kGy. Moreover, nanoclay moderated the effect of the irradiation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42393.

Dyeing Properties and Color Fastness of Chitosan Treated Cotton Fabrics with Thian King Leaves Extract

Chitosan, a naturally available biopolymer, was used as finishing agent to increase dye uptake and color fastness of cotton fabrics. Thian King leaves extract a natural dye was applied on cotton fabrics after chitosan treatment. The whiteness index and tensile strength of samples were measured to study the effect of chitosan application. The color of dyed samples was investigated in term of the colorimetric parameters (L*, a*, b*, ∆E) and K/S values. The color fastness to washing, rubbing and light of dyed samples was determined according to AATCC test method. The results showed that the chitosan concentration enhances the whiteness index and tensile strength of the treated cotton fabrics. Chitosan treatment showed increase dye uptake of cotton fabrics. Fastness properties of these to washing, rubbing and light have also been discussed.

Influence of Structural Parameters on Tensile Property of Gasar Porous Copper

Abstract Gasar porous copper with various structural parameters was made by metal-gas eutectic unidirectional solidification process. The effects of structure parameters on the uniaxial tensile properties of the porous copper were investigated. The fracture morphologies of tensile samples were studied by scanning electron microscope (SEM). Math models and numerical simulation were performed and confirmed by experimental data. Results show that the tensile properties of porous copper depend on porosity and tensile direction. Ultimate tensile strength of samples with the same porosity whose pore axes are parallel to tensile direction is better than that whose pore axes are perpendicular to tensile direction. For the porous copper whose pore axes are parallel to tensile direction, the ultimate tensile strength decreases linearly with increasing of the porosity, indicating that pores have no stress concentration on matrix. While for the porous copper whose pore axes are perpendicular to tensile direction, the ultimate tensile strength decreases significantly as porosity increases. Ultimate tensile strengths from experiments, models and numerical simulations of two kinds of specimens are consistent well.

Spark Plasma Sintering of Mechanically Activated Ni and Al Nanopowders

The structure and mechanical properties of materials fabricated by spark plasma sintering of mechanically activated mixture of nickel and aluminum nanopowders were investigated. On account of the elemental powders ratio formation of Ni3Al compound was expected. Relative density of sintered samples was equal to ~ 95 %, microhardness of materials was 6540 MPa. Ultimate tensile strength of samples tested according to three-point bending scheme exceed 1100 MPa.

The Impact to WELDOX960 Steel Welding Joint Made by Strength Match

As new generation of low alloy high strength steel, WELDOX960 is extensively applied into heavy-duty fields including engineering machine etc. This paper adopts mixed gas protection welding to make multi-layer and multi-channel welding to low alloy high strength steel WELDOX960, using match methods with different intensities to prepare six groups of samples, respectively. The performances including joint tension and impact etc are tested for analysis after welding. The result shows that backing welding is the most important technique process in multi-layer and multi-channel welding, which has significant impact to joint performance, in the precondition that the strength is satisfied, if the material with lower strength is taken as backing layer, toughness and plasticity of the joint can be improved significantly. For example, tensile strength of sample 50-90 reaches 966.3Mpa, which is the same as 90-90, however, its toughness increases by 15%.