Decrease In Tensile Properties Research Articles

Enhancing performance: insights into the augmentation potential of acrylonitrile butadiene styrene/boron nitride composites

Abstract This work aims to investigate the morphological, mechanical and thermal characteristics of boron nitride (BN)-reinforced acrylonitrile-butadiene styrene (ABS) composites. ABS and ABS/BN composites with a maximum BN loading up to 8 wt% were developed using two-roll mill followed by compression molding. Scanning electron microscopy (SEM) images presented interlinking of BN flakes in the dimple texture of ABS. A modest decrease in tensile properties was observed for the composites. The tensile strength and impact strength for the ABS/BN8 specimen were lowered by 4.7 and 81.7 %, respectively. On the other hand, hardness increased by 3.39 % for ABS/BN8 composite. The interaction effect of BN in the ABS matrix on the thermal properties was assessed using thermo-gravimetric analysis (TGA). An enhancement in the thermal-stability was observed for BN incorporated ABS. There is a modest shift in glass transition (T g) temperature to a higher value for the ABS/BN composites.

Mixture design optimization and machine learning-based prediction of Al-Mg alloy composite reinforced by Zn nanoparticles: A molecular dynamics study

Al-Mg alloy is widely used in various industries due to its practicality. It is crucial to achieve the highest possible tensile properties for this alloy. In this study, first, Zn nanoparticles were combined with the aluminum-magnesium alloy to modify their tensile properties. Then, a mixture design of experiment was utilized to find the best combination of Al-Mg-Zn alloy, which was validated through molecular dynamics simulation. Mechanical tests were also conducted on Al-1%Mg-1%Zn alloy at different temperatures and strain rates. The results suggested that when the temperature increases, the tensile properties decrease, while with higher strain rates they increase. Furthermore, four machine learning-based algorithms including Generalized Linear Model (GLM), Artificial Neural Network (ANN), Decision Tree (DT), and Random Forest (RF) were compared to determine the simplest and the most accurate one for the prediction of mechanical properties of Al-Mg-Zn alloy and due to the highest values of correlation coefficient, the ANN algorithm was found as the most accurate one for the prediction of mechanical properties. The GLM algorithm was also known as an appropriate algorithm to predict the mechanical properties. However, the DT and RF algorithms had low prediction precisions. Therefore, the parameters that were influential in the prediction precision of DT and RF algorithms were changed, and the best value of each parameter was obtained. It was found that the DT algorithm with a maximum depth of 6 has the highest precision prediction of mechanical properties. Furthermore, the RF algorithm had the highest accuracy for the prediction of mechanical properties with No. of trees = 4 and maximum depth = 4.

Effect of Silicon Carbide Reinforcement on Wear Properties of A Glass Epoxy Composite for Aircraft Application

In the present investigation, the tensile and sliding wear properties of silicon carbide filled with glass epoxy polymeric composites were studied. The composites were prepared by dispersing different weight percentage of micro silicon carbide fillers in epoxy matrix and the mixture is then laid up on glass woven fabric by hand layup technique. Specimens were prepared out of the cured laminates and tests were conducted to study their tensile and wear properties. The test matrix for wear tests is defined using Taguchi approach. Sliding wear resistance increased with increase in SiC filler percentage though there has been a marginal decrease in tensile properties.

Effect of Mechanical Recycling on the Mechanical Properties of PLA-Based Natural Fiber-Reinforced Composites

The present study investigates the feasibility of utilizing polylactic acid (PLA) and PLA-based natural fiber-reinforced composites (NFRCs) in mechanical recycling. A conical twin screw extrusion (CTSE) process was utilized to recycle PLA and PLA-based NFRCs consisting of 90 wt.% PLA and a 10 wt.% proportion of either basalt fibers (BFs) or halloysite nanotubes (HNTs) for up to six recycling steps. The recycled material was then injection molded to produce standard test specimens for impact strength and tensile property analysis. The mechanical recycling of virgin PLA led to significant discoloration of the polymer, indicating degradation during the thermal processing of the polymer due to the formation of chromatophores in the structure. Differential scanning calorimetry (DSC) analysis revealed an increase in glass transition temperature (Tg) with respect to increased recycling steps, indicating an increased content of crystallinity in the PLA. Impact strength testing showed no significant detrimental effects on the NFRCs’ impact strength up to six recycling steps. Tensile testing of PLA/HNT NFRCs likewise did not show major decreases in values when tested. However, PLA/BF NFRCs exhibited a significant decrease in tensile properties after three recycling steps, likely due to a reduction in fiber length beyond the critical fiber length. Scanning electron microscopy (SEM) of the fracture surface of impact specimens revealed a decrease in fiber length with respect to increased recycling steps, as well as poor interfacial adhesion between BF and PLA. This study presents a promising initial view into the mechanical recyclability of PLA-based composites.

The Longer-Term Effects of a Single Bupivacaine Exposure on the Mechanical Properties of Native Cartilage Explants.

The purpose of this study was to determine the in vitro effects of a single exposure of bupivacaine on the mechanical properties of bovine cartilage explants at 3 weeks. Femoral condyle articular cartilage explants were aseptically harvested from juvenile bovine stifle joints before being exposed to chondrogenic medium containing 0.50% (wt/vol) bupivacaine, 0.25% (wt/vol) bupivacaine, or no medication (control) for 1 hour. Explants were then washed and maintained in culture in vitro for 3 weeks before testing. Cell viability, tensile and compressive mechanical properties, histological properties, and biochemical properties were then assessed. Explants exhibited a dose-dependent decrease in mean tensile Young's modulus with increasing bupivacaine concentration (9.86 MPa in the controls, 6.48 MPa in the 0.25% bupivacaine group [P = 0.048], and 4.72 MPa in the 0.50% bupivacaine group [P = 0.005]). Consistent with these results, collagen content and collagen crosslinking decreased with bupivacaine exposure as measured by mass spectrometry. Compressive properties of the explants were unaffected by bupivacaine exposure. Explants also exhibited a trend toward dose-dependent decreases in viability (51.2% for the controls, 47.3% for the 0.25% bupivacaine-exposed group, and 37.0% for the 0.50% bupivacaine-exposed group [P = 0.072]). Three weeks after 1-hour bupivacaine exposure, the tensile properties of bovine cartilage explants were significantly decreased, while the compressive properties remained unaffected. These decreases in tensile properties corresponded with reductions in collagen content and crosslinking of collagen fibers. Physicians should be judicious regarding the intra-articular administration of bupivacaine in native joints.

Evaluation of Tensile Properties and Microstructure of a Scraped Gas Turbine Blade using Miniature Specimens

A gas turbine (GT) blade is a key hot-pass component for advanced GT engines, and should have stable properties under extreme conditions of 1,350°C and 3,600rpm, etc. The GT blade, after operating with nearly 800 equivalent start-stops (ES) or 24,000 equivalent operation hours (EOH), should be replaced due to degradation of properties and microstructure, particularly, the formation of cracks in the airfoil tip and platform region. To date, the assessment of materials, prototype blade, etc, has been extensively studied in a laboratory simulated environment; however, evaluation of the full-scale blades in a service environment has been rarely reported. Here, the properties and microstructures of an F-class GT first stage blade, with a service history of 800ES were investigated. The results showed decreasing tensile properties at the airfoil part due to its higher temperature exposure. The microstructural characterization results revealed that the finer grain size and dendrite interfaces facilitated the formation of Cr-enriched M<sub>23</sub>C<sub>6</sub> along grain boundaries, as well as the spherical γ' in the airfoil part, resulting in a decrease in tensile properties. The results obtained here provide precious background for assessing the serviced blade and developing advanced blades.

Influence of high-temperature, high-pressure, and acidic conditions on the structure and properties of high-performance organic fibers

Abstract Aramid and poly(p-phenylene benzobisoxazole) (PBO) fibers are two of the most represented organic fibers possessing high strength, high modulus, excellent thermal stability, and chemical resistance, with great potential in oil and gas applications. The reliability of organic fibers for oil and gas applications were systematically evaluated by studying the corrosion behavior and mechanisms in high-temperature and high-pressure (HTHP) hydrogen sulfide (H2S) and carbon dioxide (CO2) corrosive environments. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), elemental analysis, density measurements, and single fiber tensile testing were conducted to study the surface morphology, chemical structure, crystal structure, thermal, and mechanical properties of aramid and PBO fibers, before and after corrosion. After corrosion, the crystallinities of aramid and PBO fibers decreased by 19.4 and 4.4%, respectively, whereas their tensile fracture strengths decreased by 50.34 and 28.18%, respectively. Hence, the corrosion resistance of PBO fiber is better than aramid fiber. The decrease in tensile properties of aramid and PBO fibers can be attributed to the higher internal porosity, more number of surface defects, and lower crystallinity after HTHP H2S/CO2 corrosion. This work provides some fundamental information regarding the selection of high-performance organic fibers for oil and gas applications.

Investigation of the Mechanical Properties of Vinylester-Based Sheet Moulding Compound (SMC) Subject to Particle Recycling

In light of climate change, fiber-reinforced plastics (FRP) are becoming increasingly important due to their lightweight construction potential. This benefit is additionally expanded on with the low cycle times, scrap rates and material costs of Sheet Moulding Compounds (SMC), making it the most often used material on the FRP market. While extensive studies regarding the recycling of SMC with unsaturated polyester-based matrices (UP-SMC) have been conducted in the past, this is not the case for vinylester-based SMC (VE-SMC). In this research, VE-SMC components were subject to a particle-recycling approach. Recyclate in the form of VE-SMC regrind was used to substitute SMC matrices during the compounding process. The dependence of the mechanical properties and failure behavior of VE-SMC containing regrind was investigated by means of microscopic and mechanical test methods for varying mass proportions of SMC regrind. Due to the addition of SMC regrind, a decreased fiber/matrix adhesion was observed. Furthermore, an increase in pore formation was observed with an increasing proportion of SMC regrind. The flexural modulus increased by 20% with a low percentage of regrind (ωrSMC = 10 wt.%) in comparison to virgin SMC. In contrast, the tensile properties decrease (up to 30%) with the addition of SMC regrind independent of the investigated proportions of SMC regrind.

On Mechanical Response of Aluminum Alloys in Corrosive Environment

Al6061T6 and Al7075T6 aluminum alloys are subjected to accelerated salt spray corrosion to evaluate the amount of degradation and the effect on mechanical behavior. The specimens were stored in a closed chamber with continuous salt spray for a period of 250 hours and 500 hours, respectively. It was observed that the oxide layer was unprotective after prolonged salt spray resulting in pitting continued with exfoliation corrosion. The tensile test results show that there was a remarkable decrease in tensile properties with exposure time. A significant reduction in tensile strength, yield strength, elongation at yield, elongation at break, and overall toughness in both the alloys was observed at 500 hours. The impact strength decreased by 14.4 % and 26.47 %, Rockwell hardness (HRB) reduced by 12.2% and 20.71% for respective alloys at 500 hours of exposure. However, there was an increasing trend in elastic stiffness which attributed to decrease in ductility. Furthermore, it was comparatively observed that Al7075T6 is more susceptible to corrosion than Al6061T6.

Effect of stitching on improving the tensile strength of sisal fabric/epoxy composites for internal bone plate applications

Permanent metallic implants have been used traditionally for orthopaedic bone fractures. Though metallic bone plates are medically acceptable, they are also linked with numerous weaknesses like a modulus disparity, corrosion, and delay in fracture healing. Hence, preparing biodegradable implants using bio-composites is the current trend in research. Natural materials may be a good alternative due to their properties closer to the mechanical properties of bone and easily biodegradable too. Sisal is one of the degradable and reprocessing natural fibers, which can be used for implant applications. Nevertheless, low stiffness and strength properties are a common issue in the natural-based composite. However, the high moisture absorption behaviour of natural fibers leads to a loss of mechanical properties. These issues in the natural composite structures can be resolved by stitching methods. Hence, in this connection, the strengthening of composite in the thickness direction was done through the stitching process on improving the tensile properties of non-treated sisal fabrics/biodegradable epoxy resin composite. The results showed that the stitching aided in avoiding the complete withdrawal of fibers by bonding in the thickness direction. The results also showed that an improvement of tensile strength in the stitched composite was around 90% higher than the non-stitched specimen. An in-vitro degradation test was done to estimate the reduction of mechanical strength during biodegradation. The study also proved that stitched sisal composite surges less moisture compared to unstitched composite. Though there was a slight decrease in tensile properties of the composite due to moisture, yet stitched composite could be employed as a bone plate due to their enough tensile strength. Thus, the decomposable stitched sisal composites are a capable substitute bone plate for patients, as they offer provisional mechanical support at the fracture site.

Comparative study on the properties of starch-based bioplastics incorporated with palm oil and epoxidized palm oil

This study aimed to modify the starch-based bioplastics with acceptable mechanical and water resistance properties using palm oil (PO) and epoxidized palm oil (EPO). The structural, thermal, mechanical and water resistance properties of the resulted bio-composites were evaluated. EPO had better compatibility within the starch matrix than PO. The bioplastics with PO and EPO exhibited different melting behaviors. Low concentrations of oils (<3 wt%) improved the tensile strength and elongation at break of the bioplastics remarkably, while higher concentrations of oils caused the decrease of tensile properties due to phase separation. Comparatively, EPO was more efficient at enhancing tensile properties than PO due to the presence of epoxy groups. Both oils reduced the water uptake and solubility of the bio-composites slightly. In conclusion, the addition of EPO was a more attractive way to enhance the properties of starch-based bioplastics.

Additive Manufacturing of Plastics Used for Protection against COVID19-The Influence of Chemical Disinfection by Alcohol on the Properties of ABS and PETG Polymers.

In this paper, the influence of disinfection on structural and mechanical properties of additive manufactured (AM) parts was analyzed. All AM parts used for a fight against COVID19 were disinfected using available methods—including usage of alcohols, high temperature, ozonation, etc.—which influence on AM parts properties has not been sufficiently analyzed. During this research, three types of materials dedicated for were tested in four different disinfection times and two disinfection liquid concentrations. It has been registered that disinfection liquid penetrated void into material’s volume, which caused an almost 20% decrease in tensile properties in parts manufactured using a glycol-modified version of polyethylene terephthalate (PETG).

On the tensile properties and failure mechanisms of 3D six-directional braided composites at elevated temperatures

Three-dimensional six-directional (3D6d) braided composites with different braiding angles were prepared, and the influences of temperature and braiding angle on tensile properties and failure mechanisms were studied. The results show that both temperature and braiding angle have significant effects on the tensile properties of 3D6d braided composites. As temperature increases, due to the weakening of the fiber/matrix interface, the stress-strain curve shows a nonlinear upward trend and the tensile properties decrease. As braiding angle increases, the curve declines, and both the tensile strength and modulus diminish. At high temperatures, the damage pattern is mainly braiding fibers multiple shear fracture, fifth fibers tensile fracture, sixth fibers torn, showing expansion outwards, matrix softening and peeling off from the fiber bundles. At 150 °C, the composite shows shear fracture, as the braiding angle increases, the shear fracture characteristics along the braiding angle become prominent. At 200 °C, the composite distorts and expands outwards overall. The fibers pull-out feature become obvious with increasing the braiding angle.

Change of Tensile Properties with Aging Time and Temperature in Al-Si-Cu-Mg 354 Cast Alloys with/without Minor Addition of Ni and/or Zr

The principal aim of the present research work was to investigate the effects of minor additions of nickel and zirconium on the strength of cast aluminum alloy 354 at room temperature (25°C). A decrease in tensile properties of ∼10% with the addition of 0.4 wt.% nickel is attributed to a nickel-copper reaction which interferes with the formation of Al2Cu precipitates. The platelet-like phases (Al,Si)3(Zr,Ni,Fe) and (Al,Si)3(Zr,Ti) are the main features observed in the microstructures of the tensile samples of alloys with Zr additions. The reduction in mechanical properties is due to the increase in the percentage of intermetallic phases formed during solidification; such particles would act as stress concentrators, decreasing the alloy ductility. The main effect of Zr addition lies in a significant reduction in the alloy grain size ∼40%, rather than an increase in the mechanical properties. Quality index charts could be used in assessing the effects of the Ni and Zr additions to the base alloy, as well as evaluating the heat treatment relationships to the alloy tensile properties, in particular when the system shows multiple precipitation reactions. Due to the high liquidus temperature of the Al-Zr binary phase diagram, addition of Zr beyond 0.2% is not recommended to avoid undissolved Zr.

Effect of nitrogen or boron impurities on the mechanical and vibrational properties of graphene nanosheets: a molecular dynamics approach

Investigation of mechanical and vibrational properties of nano-structures using the analytical methods would be time-consuming. Therefore, using a semi-empirical method would reduce the time needed to investigate materials characterisation. One of the semi-empirical approaches is molecular dynamics. In this Letter, the large-scale atomic/molecular massively parallel simulator software is used to simulate the mechanical and vibrational behaviour of a nitrogen- and boron-doped 24.04 × 51.13 A graphene nano-sheet. The natural frequencies, Young's modulus, and ultimate tensile strength (UTS) are studied. By adding impurity to the nanosheet and increasing its density, Young's modulus, UTS, and natural frequencies were decreased. The decrease in tensile properties was more significant in the case of boron impurity. When the boron (nitrogen) impurity increased to about 20%, Young's modulus and the first natural frequency were decreased 7.1% (9%) and 16.8% (73%), respectively. This illustrates that Young's modulus and natural frequencies are directly related. Therefore, for the same dimensions and boundary conditions, it is obvious that the increase in impurity content has reduced the natural frequencies of the nanostructure.

Influence of lignin content in cellulose pulp on paper durability

Paper degradation on a macroscopic scale is characterised primarily by yellowing, an increase in brittleness, and other destructive changes caused by the hydrolysis of glycoside bonds and oxidation reactions. Until now, lignin has been believed to cause these changes. However, contemporary analysis has not confirmed this assumption and has attributed low paper resistance to ageing with acidification owing to the production in acid environments that involve aluminium sulfate. In view of the common belief this manuscript presents studies on the accelerated ageing of papers with different lignin contents that are produced in neutral environments. To achieve the objective, artificially aged papers under conditions of increased humidity and temperature were investigated using chromatographic (SEC) and spectroscopic (FTIR and UV–Vis spectroscopy) techniques. Mechanical tests were used to determine the decrease in tensile properties of the samples. We observed no effects of the lignin content on the ageing rate of paper produced at neutral pH. This work also reveals the extent to which spectroscopic methods are useful for studying the papers containing lignin.

Effect of Ru on tensile behavior and deformation mechanism of a nickel-based single crystal superalloy

The effects of Ru on the tensile properties and deformation mechanism of the two alloys were investigated in detail at room temperature, 760 °C and 1100 °C. The microstructures of the two alloys after the tensile deformation were obtained via the TEM. Based on the microstructures, the increase of Ru further reduced the stacking faults energy at room temperature and 760 °C, which promoted the formation of stacking faults in the γ matrix and γ' phase. These stacking faults were seldom observed in the previous works. On the other hand, the slipping of dislocations was effectively hindered due to the stacking faults, which was contributed to tensile properties and work-hardening. Moreover, the dislocation pile-up groups were mainly shown on the γ/γ' interface of the alloy containing 2.5 wt % Ru at 760 °C, which was conducive to the work-hardening but harmful to the tensile properties. Hence, the yield strength and ultimate tensile stress were significantly improved with the increase of Ru at room temperature and 760 °C. The brittleness of the two alloys was improved with the increase of Ru at 760 °C due to the combined action of stacking faults, K–W locks, increase of the strength of γ' phase and high flow stress. Besides, the motion of the dislocations changed from cutting into the γ' phase to bowing out the γ' phase at 1100 °C. This movement mode of dislocations was promoted with the increase of Ru due to the wider γ matrix channels, which induced a slight decrease in tensile properties. Finally, the relation between deformation mechanisms and tensile behaviors was explained in detail according to the microstructures and tensile curves.

Effect of soil burial on silane treated and untreated kenaf fiber filled linear low-density polyethylene/polyvinyl alcohol composites

In recent decades, natural fibers have become widely used with petroleum based polymers such as polyethylene (PE) and polypropylene (PP) because of their light weight, lower cost, and inherent biodegradability. In the present work, linear low-density polyethylene/polyvinyl alcohol (LLDPE/PVOH) composites with untreated kenaf and silane-treated kenaf at filler loadings of 0, 10, and 40 phr were prepared via the melt mixing process. The soil burial test was used to evaluate the degradability of the composites for different durations (90 and 180 d). The tensile properties, surface morphology, chemical composition, percentage of weight loss, and crystallinity of the composites before and after degradation were evaluated. With increased kenaf loading and soil burial duration, all the composites showed a decrease in tensile properties. This was further confirmed by the changes in surface morphology and chemical structure of the buried composites. The increase in weight loss percentage and crystallinity after soil burial indicated that the longer burial duration had increased the degradation of composites. Composites with silane-treated kenaf exhibited lower degradability than that of composites with untreated kenaf after being buried for 90 and 180 d. This may be attributed to the improved adhesion of kenaf to the LLDPE/PVOH matrix via silane treatment.

Temperature effects on the mechanical properties of hybrid composites reinforced with vegetable and glass fibers

Although there are numerous applications for composite materials reinforced with vegetable textile fibers in outdoor parts and components (e.g., acoustic or thermal insulation panels in construction, furniture for gardens), only a few studies have reported the effects of temperature on hybrid composites reinforced with both glass and vegetable fibers. The main goal of this study was to analyze the effects of temperature on the tensile properties of five types of polymeric composites with different reinforcements: jute fabric, glass and jute fabric, flax fabric, glass and flax fabric, and glass fabric. Our method consisted of tensile testing all five types of composites at room temperature (20 °C) and other different temperatures (50 °C and 70 °C). The greatest values of reduction in tensile strength were recorded for hybrid composites. Reductions of 42.3% and 49.6% at 50 °C and 70 °C, respectively, were observed for the composite reinforced with flax and glass fibers. Reductions of 34.6% and 60% at 50 °C and 70 °C, respectively, were observed for the composite reinforced with jute and glass fibers. Finite element analysis of representative volume elements was conducted to compute the residual thermal stresses developed in the fibers and in the matrices at interfaces. It was determined that the thermal stresses cause micro-cracks at the interfaces. Thermogravimetric analysis and microscopic analysis were also conducted to identify the causes of the significant decreases in tensile properties. The effects of the anisotropy of flax and jute fibers on the thermal stresses developed at fiber-matrix interfaces were analyzed as well.

Effects of plasma treatment on properties of carbon fiber and its reinforced resin composites

The influence of plasma treatment on the wettability of carbon fiber was studied using the vacuum assisted resin transfer molding (VARTM) process. The influence of plasma treatment on the mechanical properties of carbon fiber-reinforced polymer (CFRP) composites, including interlaminar shear strength and tensile properties, were investigated. The carbon fiber surface chemistry analysis was carried out by Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). Results showed that low-temperature plasma treatment had little effect on the surface morphology of the carbon fiber; however, it changed the chemical surface state of the carbon fiber, which contributed to enhance the wettability of the carbon fiber by increasing the perfusion speed of the resin to be more than two times of the original speed. The fiber wettability improvements are of great significance to the preparation of the CFRP composite by the VARTM process. Compared to untreated carbon fiber, the plasma treatment caused an acceptable decrease in tensile properties and offered an increase in the interlaminar shear strength of the CFRP composite. Low-temperature plasma treatment played an important role in the effective preparation and application of the CFRP composite.