Increase In Bending Strength Research Articles

SYNTHESIS OF COMPOSITE POLYMER FOR INDUSTRIAL APPLICATION

The Method of Fused Deposition Modelling is most popular rapid prototyping process producing parts layer by layer which is mainly made up of polymer. But the use of these parts is restricted because of low strength of plastic. To achieve efficient mechanical properties, metal composite polymer can be used which has not been used as feedstock material in FDM. Plastic component are most commonly produced by injection molding process. Wide variety of shapes and sizes of thin walled plastic parts are manufactured by this method . The aim of present study was to fabricate new metal composite and to investigate the effect of addition of metal powder on strength of polymer. As both FDM and Injection moulding are similar process the feasibility of metal composite feedstock was checked in injection moulding process. Experiments were carried out on parts produces by injection moulding process with different composition of metal and polymer. Six specimens with different proportions of aluminum and copper in polymer by weight were prepared as per the ASTM standard for Tensile and Flexural test. It can be concluded that addition of copper increases tensile strength of parts and aluminum increases bending strength of parts produced by Injection Moulding process.

Mechanical strength evaluation of composites made from waste printed circuit boards (PCBs)

ABSTRACTSustainable resource recovery and recycling forms an integral part of a developed and developing economy. In line with this universally acceptable sustainable practice, the feasibility of utilizing the nonmetallic fraction (NMF) from waste printed circuit boards (PCBs) as a reinforcing additive in the waste polyvinyl chloride (PVC) from the piping industry to form a usable composite material was investigated. Mechanical strength evaluation of PCB–PVC composites was investigated in terms of morphological NMF powder properties and fracture analysis at surfaces of PCB–PVC composites. The acquired results showed that the NMF addition to a certain limit can significantly improve the mechanical strength properties of waste PVC such as the tensile strength, bending strength, and modulus. An optimum NMF ratio value of 20% for improved mechanical strength properties was identified. Adding 500 µm NMF with optimum weight ratio increased the tensile strength (40%), tensile modulus (38.8%), bending strength (12.7%), and bending modulus (31%) of composites in comparison with nonadditive recycled PVC. Further it was observed that changing the NMF particle size from 500 to 150 µm decreased the tensile strength (7.14%), modulus (16%) and increased bending strength (7.74%) and modulus (5.7%). This investigation suggests that the waste NMF of PCBs in the identified optimum weight ratio can form an effective addition to the waste (PVC) to improve its mechanical strength properties. The effective use in this manner will lead to a promising new way of recycling the waste NMF of PCBs resulting in potential new uses by simultaneous sustainable waste reduction and reuse of otherwise a hazardous waste.

Ultra High Performance Concrete Reinforced with Short Steel and Carbon Fibers

<p class="R-AbstractKeywords"><span lang="EN-US">Fibers are usually used in High Performance Concrete with a purpose to increase bending strength and ductility. Important properties are the peak value of bearing stress (strength) and post-cracking behavior of bended element. In the framework of an experimental part, Ultra High Performance mix compositions were prepared using intensive mixer. Short steel fibers and carbon micro fibers in amount of 1% by volume, as well as its combination were used for cement matrix reinforcing. Results of compressive and bending tests proved an increase of strength value in the case of use both steel and carbon fibers. Carbon fibers were decreased the effect of explosive collapse of the UHPC cement matrix, at the same time still brittle bending behavior was take place. Steel fibers considerably improved bending ductility thanks to a pull-out mechanism of steel fibers. The best results were achieved in the case of combined application of both carbon and steel fibers.</span></p>

Elimination of strength degrading effects caused by surface microdefect: A prevention achieved by silicon nanotexturing to avoid catastrophic brittle fracture.

The unavoidable occurrence of microdefects in silicon wafers increase the probability of catastrophic fracture of silicon-based devices, thus highlighting the need for a strengthening mechanism to minimize fractures resulting from defects. In this study, a novel mechanism for manufacturing silicon wafers was engineered based on nanoscale reinforcement through surface nanotexturing. Because of nanotexturing, different defect depths synthetically emulated as V-notches, demonstrated a bending strength enhancement by factors of 2.5, 3.2, and 6 for 2-, 7-, and 14-μm-deep V-notches, respectively. A very large increase in the number of fragments observed during silicon fracturing was also indicative of the strengthening effect. Nanotextures surrounding the V-notch reduced the stress concentration factor at the notch tip and saturated as the nanotexture depth approached 1.5 times the V-notch depth. The stress reduction at the V-notch tip measured by micro-Raman spectroscopy revealed that nanotextures reduced the effective depth of the defect. Therefore, the nanotextured samples were able to sustain a larger fracture force. The enhancement in Weibull modulus, along with an increase in bending strength in the nanotextured samples compared to polished single-crystal silicon samples, demonstrated the reliability of the strengthening method. These results suggest that this method may be suitable for industrial implementation.

Effect of screw position on single cycle to failure in bending and torsion of a locking plate-rod construct in a synthetic feline femoral gap model.

To evaluate the effect of screw position on strength and stiffness of a combination locking plate-rod construct in a synthetic feline femoral gap model. 30 synthetic long-bone models derived from beechwood and balsa wood. 3 constructs (2 locking plate-rod constructs and 1 locking plate construct; 10 specimens/construct) were tested in a diaphyseal bridge plating configuration by use of 4-point bending and torsion. Variables included screw position (near the fracture gap and far from the fracture gap) and application of an intramedullary pin. Constructs were tested to failure in each loading mode to determine strength and stiffness. Failure was defined as plastic deformation of the plate or breakage of the bone model or plate. Strength, yield angle, and stiffness were compared by use of a Wilcoxon test. Placement of screws near the fracture gap did not increase bending or torsional stiffness in the locking plate-rod constructs, assuming the plate was placed on the tension side of the bone. Addition of an intramedullary pin resulted in a significant increase in bending strength of the construct. Screw positioning did not have a significant effect on any torsion variables. Results of this study suggested that, in the investigated plate-rod construct, screw insertion adjacent to the fracture lacked mechanical advantages over screw insertion at the plate ends. For surgeons attempting to minimize soft tissue dissection, the decision to make additional incisions for screw placement should be considered with even more caution.

Co-effects of graphene oxide sheets and single wall carbon nanotubes on mechanical properties of cement

The enhancement of mechanical properties of cement composites by a carbon nanomaterial is an important topic. However, the co-effect of two (or more) carbon nanomaterials on the mechanical properties of cement has not been explored. In this paper, it was found that the mixture of graphene oxide (GO) sheets and single-walled carbon nanotubes (SWCNTs) exhibited an excellent co-effect, leading to 72.7% increase in bending strength of cement, which is much larger than the strength enhancements of 51.2% by GO and 26.3% by SWCNTs. Furthermore, it was demonstrated that the bending strength of cement composite materials with GO and SWCNTs is proportional to the sizes of crystal SiO2 particles.

Magnesium Alloy AZ31 - Short Carbon Fiber Composite Obtained by Pressure Die Casting

The application of short carbon fibers in magnesium alloy AZ31 matrix composite fabrication by cold chamber pressure die casting was presented. A technological procedure of small-sized and complex-shaped composite casts manufacturing was shown. The microstructure of the composite was characterized as well as its mechanical properties, friction coefficient and wear resistance. The application of mechanical stirring of melted AZ31 alloy with short fibers and then AZ31-Cf suspension pressure die casting ensured obtaining casts with the reinforcing phase correctly distributed and well bonded with the matrix. Comparision of the AZ31-Cf composite with the AZ31 alloy properties, cast in the same conditions, revealed a considerable increase in bending strength and hardness, and some improvement of ductility and sliding friction parameters as a result of short carbon fibers application.

Effect of Composite Action on the Strength of Wood Roofs

Engineering certification for the installation of solar photovoltaic modules on wood roofs is often denied because existing wood roofs do not meet current building codes. Rather than requiring expensive structural retrofits, we desire to show that many roofs are actually sufficiently strong if the effect of composite action produced by joist-sheathing interaction is considered. In a series of laboratory experiments using a limited number of two-by-four wood joists with and without sheathing panels, conventionally sheathed stud-grade joists, surprisingly, exhibited between 18% and 63% higher nominal strength than similar bare joists. To explain this strength increase, a simple model was developed to predict the strengths of the nailed partially composite sections, but the model only justifies a 1.4% to 3.8% increase in bending strength of joists with an allowable bending strength of 1000 psi. More testing is indicated to resolve this discrepancy between laboratory results and analytical modeling results. In addition to elucidating nonlinear partial composite behavior of existing roof systems, this paper shows that, with minor changes in roof framing practices, strength increases of 70% or more are achievable, compared to the strengths of conventionally sheathed joists.

Microstructure and properties of ultrafine WC–Co–VC cemented carbides with different Co contents

Ultrafine WC–Co–VC cemented carbides are used extensively in a variety of industrial environments due to their excellent mechanical properties and outstanding wear resistance. Co content affects the service performance of the cemented carbides. In the present study, the influences of Co content on microstructure, physical, and mechanical properties were investigated systematically. Ultrafine WC–Co–VC cemented carbides with Co content varying from 4 wt% and 7 wt% and assistance of VC (0.35 wt%) as inhibitor of WC grain growth were prepared. The physical and mechanical properties were tested and the microstructure characteristics were observed by optical microscope (OM) and scanning electron microscopy (SEM). From the results, it is found that with Co content increasing, both the cobalt magnetism and bending strength increase, while the coercive force, Rockwell hardness, density, and abrasive wear resistance decrease. In addition, the OM and SEM results show that the increase of Co content in WC–Co–VC cemented carbides tends to reduce the quantity and size of micro-pores, and make the fracture mode change from brittle fracture to ductile fracture.

Mechanical properties of chemically modified portuguese pinewood

To turn wood into a construction material with enhanced properties, many methods of chemical modification have been developed in the last few decades. In this work, mechanical properties of pine wood were chemically modified, compared and evaluated. Maritime pine wood (Pinus pinaster) was modified with four chemical processes: 1,3-dimethylol-4,5-dihydroxyethyleneurea, N-methylol melamine formaldehyde, tetra- alkoxysilane and wax. The following mechanical properties were assessed experimentally: Modulus of elasticity measured statically, stiffness stabilization efficiency in different climates (30 and 87% of relative humidity), modulus of rupture, work maximum load, impact bending strength, compression, tensile and shear strength at indoor conditions (65% of relative humidity). In both types of active principle of modification, cell wall or lumen fill, no significant changes on the bending stiffness (modulus of elasticity) were found. In the remaining properties analysed significant changes in the modified wood-material took place compared to unmodified wood control: - Cell wall modification was the most effective method to achieve high stiffness stabilization efficiency (up to 60%) and also increased compression strength (up to 230%). However, modulus of rupture, tensile, shear and the impact bending strength were reduced by both resins, but in a varying extent, where the N-methylol melamine formaldehyde endured less reduction than 1,3-dimethylol-4,5-dihydroxyethyleneurea resin. In the latter, reduction up to 60% can take place. - In the lumen fill modification: tetra-alkoxysilane has no effect in the mechanical properties. Although, a slight increase in shear strength parallel to the grain was found. Wax specimens have shown a slight increase in bending strength, compression, tensile and shear strength as well as in the absorption energy capacity.

Analysis of the Mechanical Properties of TC4-6061 Composite Plate Based on Classical Laminate Theory

The calculation formula for the mechanical properties of TC4-6061 composite plate was deduced based on classical laminate theory. The stiffness, the strength, the specific stiffness and the specific strength for the plates was calculated by using the formula. The results show that with increasing of the relative thickness of titanium alloy layer, the tensile stiffness, the bending stiffness, the tensile strength and the bending strength increase rapidly, the tensile stiffness and tensile strength change little, the bending stiffness and specific bending strength first increase and then decrease.

Preparation and Characterization of SiC Whisker-Reinforced SiC Porous Ceramics for Hot Gas Filtration

SiC porous ceramics (SCPCs) were fabricated by a dry press forming method and in situ reaction-bonding technique using ZrO2 as sintering aids, activated carbon as pore-forming agent, and SiC whiskers as reinforcing agent. The effects of the amount of SiC whiskers on the porosity, bending strength, microstructure, and gas permeability of the SCPCs were investigated. The results showed that without incorporated SiC whiskers, the bending strength was 9.7 MPa for the SCPCs sintered at 1550 °C, while the bending strength of the SCPCs with 3.3 wt % SiC whiskers reached 28 MPa, nearly a 3-fold increase in bending strength over that of pristine SCPCs. The SiC whiskers-enhanced ceramic supports exhibited a porosity of 44.2% and an average pore size of 14.6 μm. Moreover, the samples also showed a gas permeability of 270 m3/m2·h·kPa, which is 1.7 times higher than that of the pristine SCPCs. The bending strength remained high after 18 cold–hot cycles (800 °C), indicating good thermal shock resistance.

Preparation of PMMA/PP/ PP-g-MAH Alloy

Studies of the polypropylene grafted with malefic anhydride PP-g-MAH as compatibilizer to toughening polypropylene PP and PMMA blends. When PP/PMMA fixed ratio of 80/20, the effects of PP-g-MAH content on the blend morphology, mechanical properties and thermal properties. With the increase of PP-g-MAH content, strength and impact strength, tensile strength, PMMA/PP/PP-g-MAH blends were first increased and then decreased, and in the PP-g-MAH for 5 copies and reached the maximum value; while the flexural strength increased. The impact strength of the alloy compared with the alloy without the addition of compatibilizer increased about 30%, the tensile strength, bending strength increase obviously. That PP-g-MAH has effects on the morphology and properties of PMMA/PP/ PP-g-MAH blend system.

Fiber reinforcement during 3D printing

Three-dimensional (3D) printing is an attractive rapid prototyping technology for the fabrication of 3D structures by the localized deposition of a reactive binder liquid onto thin powder layers in predominantly technical applications. A practical limitation is often the low green strength of printed samples, which can lead to a collapse of large and fragile structures during removal from the powder bed and the following depowdering procedure. Fibre reinforcement may improve green mechanical properties of printed samples, which was investigated in this study using a range of different short fibres added to a matrix of cellulose-modified gypsum powder. Mechanical testing of printed samples revealed a bending strength increase of 180% and up to 10 times higher work of fracture values compared to non-reinforced printed samples.

Influence of Deep Cryogenic Treatment on Microstructures and Mechanical Properties of an Ultrafine-Grained WC-12Co Cemented Carbide

Effect of deep cryogenic treatment (DCT) on the microstructures and mechanical behavior of ultrafine-grained WC-12Co cemented carbide was investigated by using XRD, SEM, and DSC. The phase transformations of pure Co and binder phase Co in cemented carbide were analyzed in detail to correlate the strengthening mechanism with its α → ε phase transition. The results show that DCT resulted in a slight increase in hardness and bending strength of ultrafine-grained WC-12Co cemented carbide. For the ultrafine-grained cemented carbide after DCT, there is no significant change in the microstructure and the elemental distribution of the cemented carbides, but the fractured morphology shows a feature of plastic deformation. In the cases of pure Co and the binder phase Co in WC-12Co cemented carbide, they exhibit different features of phase transformation. The improvement of mechanical property of cemented carbide can be attributed to the increased amount of ε-Co in WC-12Co composites after DCT.

Some physical and mechanical properties of reinforced laminated veneer lumber

In this study, poplar laminated veneer lumber (LVL) was produced using phenol formaldehyde adhesive, and reinforced LVL (RLVL) was produced by inserting woven glass fibers between the veneer sheets. Some tests were conducted to analyze the effects of the reinforcement on the properties of the LVL. Some physical properties, such as density, moisture content, and swelling were determined, as were the mechanical properties of impact bending, specific impact bending, and shear strength. The test results indicated that density, impact bending, and shear strength increased. Conversely, tangential swelling, volumetric swelling, moisture content, and specific impact bending decreased. Increased dimensional stability of wood-based materials is a preferred property for many applications due to the increased service life. In addition, the increases in impact bending and shear strength, especially in the connection points and load-bearing points in structural applications, were the most important results of the study.

High Enhanced Efficiency and Mechanism of Ultra‐Long SiC Nanowires in Composites

Ultra‐long SiC nanowires with large aspect ratios of 2 × 104–5 were incorporated successfully into epoxy resin to form SiC nanowires/epoxy composite via a preliminary homogenously dispersive process in ethanol. 9.7 and 13.3% bending strength increases were achieved for the composites with the addition of very small quantity (0.1 and 0.125 wt%) of ultra‐long SiC nanowires. The prepared ultra‐long SiC nanowires have the highest enhanced efficiency than other shorter ones in epoxy resin composites. Microstructure analysis implies that the nanowire disperse homogenously in the composite and have well combination with matrix. The ultra‐long nanowires can exert their extraordinary high modulus and tensile strength of SiC nanowires in this condition. The obtained high enhanced efficiency is the mutual effect of high modulus and strength, large aspect ratio, fine distributed state, moderate interface bondings, and formed a three‐dimensional network of the ultra‐long SiC nanowires.

Preparation and properties of high-purity porous alumina support at low sintering temperature

High-purity porous alumina supports have been prepared at low sintering temperatures from alumina powders (99.99%, d50=10μm) coated by boehmite sol via electrostatic adsorption. The effects of sintering temperature and relative weight ratio of boehmite on microstructure, bending strength, porosity and pore size distribution were investigated. With sintering temperature increasing, open porosity and average pore size decrease and bending strength increases. Although open porosity and mechanical strength aren’t dependent on the weight ratio of boehmite, the adding of boehmite decreases average pore size because of the blocking of macro pores by superabundant fine crystals from excessive boehmite. The support sintered at 1500°C from mixture powders with 5.22% boehmite has an open porosity of 53.73%, an average pore size of 5.1μm, and a bending strength of 35.5MPa. Furthermore, because of its high purity, the sample is likely to have good resistance to acid and alkali corrosion.

Bulk Cr7C3 compound fabricated by mechanical ball milling and plasma activated sintering

Bulk Cr7C3 compounds were fabricated with Cr and C mixed-powder by mechanical ball milling and plasma activated sintering (PAS). The results indicate that, there is no alloying reaction between Cr and C powders at milling times from 3h to 15h; at milling times from 1h to 7h, the morphology of mixed-powder becomes finer and the distribution becomes more and more uniform; however, as milling time exceeds 7h, the morphology and distribution have no obvious change. At sintering temperature of 1648K for 2h duration, there is also Cr23C6 compound besides Cr7C3. With sintering temperature reaching 1673K and above, the single bulk Cr7C3 compound can be fabricated; however, the cracks appear at 1698K. The result also indicates that, as sintering time increases from 2h to 4h at 1673K, the relative density of bulk Cr7C3 will increase; however, as the sintering time exceeds 4h, the density has no obvious change. Furthermore, the hardness of bulk Cr7C3 increases slightly with sintering time. The bending strength and fracture toughness increase with the sintering time changing from 2h to 4h; however, they decrease slightly with the time exceeding 4h.

Increasing Bending Strength of Porcelain Stoneware via Pseudoboehmite Additions

Pseudoboehmite nanoparticles synthesized through the desulfation of Al2(SO4)3were used to investigate the reinforcement of commercial porcelain stoneware. Fractured specimens investigated by SEM suggest that the added pseudoboehmite precursor generated a nanometric primary mullite phase dispersed in the porcelain glassy phase that limited and stopped the intergranular crack propagation. The porcelain modulus of rupture increased twice the value of the modulus of rupture (108 MPa) as compared with that samples without pseudoboehmite additions. Pseudoboehmite also led to increased densification of porcelain stoneware bodies up to 1250°C as shown by thermodilatometry data.