Mechanical Property Tests Research Articles

EFFECT OF ZIGZAG AND LINE PRINTING PATTERN ON TENSILE STRENGTH AND SURFACE ROUGHNESS OF FUSED DEPOSITION MODELING PRODUCT

This research aims to test the results of 3D printing using Polylactic acid (PLA) filament on surface roughness and tensile strength. Experiments were carried out by adjusting the differences in printing fill density for the pattern used. Filling density uses variations of 60%, 80%, and 100%. The tensile test is used to measure the tensile mechanical properties of polymers (σ). The roughness test is obtained to determine the average surface roughness (Ra), root mean square roughness (Rq), and ten-point height (Rz). The test specimen uses the ASTM D638 type 4 standard model and size. The nozzle diameter is 0.4 mm, the temperature is 220 °C, and the heat bed temperature is 60 °C. The mechanical properties test results of the printing pattern showed that the zigzag pattern had the highest yield strength, maximum load, and elongation values, namely 0.97 N/mm2, 52.99 N, and 9.43%. Meanwhile, in the line pattern, the highest yield strength, maximum load, and elongation values were 1.51 N/mm2, 62.72 N, and 3.54% and the highest yield of the two patterns was in the highest printing pattern, namely 100%. It was concluded that the larger the printing pattern, the wider the filament will be, as a, result the level of surface roughness will also be higher.

Sustainable paper-based packaging from hemp hurd fiber: A potential material for thermoformed molded fiber packaging

Hemp hurd fiber, a low-value waste stream from the hemp industry, has potential downstream applications as an alternative to non-renewable plastics for single-use food service ware and packaging applications. Packaging paper substrates made from chemically pulped hemp hurd, mixed in varying ratios with bleached thermomechanical radiata pine pulp were developed and tested. Handsheets were characterized using several mechanical property tests including tensile strength, tearing resistance, burst strength, short-span compression, ring crush, together with Gurley air resistance, contact angle, and Cobb60 tests. Generally, addition of hemp hurd fibers significantly improved handsheet mechanical properties. Hot-pressing of the handsheets so as to approximate molded fiber thermoforming further enhanced their performance, with pure hemp hurd handsheets having the highest mechanical properties and barrier performance. A prototype was successfully thermoformed from hemp fiber, demonstrating overall feasibility of this fibre source for molded fibre objects.

Effect of bonding temperature on microstructure and properties of TLP joined Q355 steel with Cu interlayer

Abstract Q355 steel with Cu interlayer was bonded by transient liquid phase diffusion bonding (TLP-DB) at different bonding temperatures, and good bonding joints were obtained. The joints were characterized by optical microscopy, scanning electron microscopy and mechanical properties. The results show that there is a bending phenomenon caused by the difference of element diffusion at the bonding interface at the bonding temperature of 1050 °C. With the increase of the bonding temperature, the diffusion of Cu element plays a role in refining the grain, but with the increase of the bonding temperature, it will also lead to the overgrowth of the grain; At the bonding temperature of 1050 °C, there are obvious mutations in the diffusion of Cu and Fe elements, but the increase of the bonding temperature has a good effect on the interdiffusion of the elements. The mechanical properties test showed that with the increase of the bonding temperature, the hardness, shear strength, and impact toughness at the center of the joint increased first and then decreased, and all reached the maximum at 1100 °C. The electrochemical performance test showed that with the increase of temperature, the corrosion resistance of the joint also increased first and then decreased.

Study on Influence of Rare Earth Ce on Micro and Macro Properties of U75V Steel.

Non-metallic inclusions in steel have great influence on the continuity of the steel matrix and the mechanical properties of steel. The precipitation sequence of Ce inclusions in molten steel is predicted by thermodynamic calculations. The results show that Ce content will affect the precipitation sequence of rare earth inclusions in molten steel, and the formation of CeO2, Ce2O3 and CeAlO3 will be inhibited with the increase in Ce content. Our laboratory smelted the test steel without rare earth additive and the test steel with rare earth Ce additive (0.0008%, 0.0013%, 0.0032%, 0.0042%). It was found that the MnS inclusions and inclusions containing Al, Ca, Mg and Si oxides or sulfides in the steel after rare earth addition were modified into complex inclusions containing CeAlO3 and Ce2O2S. The size of inclusion in steel was reduced and the aspect ratio of inclusion was improved. The addition of Ce also improved the grain size of U75V steel and significantly refined the pearlite lamellar spacing. After mechanical property testing of the test steel, it was found that when Ce is increased within 0.0042%, the tensile and impact properties of U75V steel are also improved.

Increasing Added Value in Basalt Rocks for Making Basalt Fiber

Andesite and basalt are generally mined materials used only for building (construction). To increase the added value, basalt rock is currently starting to be widely used as a construction material that is converted into composites with fiber reinforcement. In this initial research, the aim is to examine the characteristics of basalt rock at three locations in the Greater Bandung area (Gunung Bohong, Cipatik, and Batu Templek), including its chemical composition, physical and mechanical properties, and mineral composition. The research methodology is carried out on three rock characteristics that can be used as basalt fiber, namely the XRF method to determine chemical composition (Al2O3 and SiO2), physical and mechanical testing, as well as the petrographic analysis method to discover mineral composition by examining the presence of Plagioclase minerals. The results of the chemical analysis of all samples are suitable, but there are chemical compounds that do not match the parameters, namely Fe2O3 + FeO and MgO. Samples from Cipatik and Batu Templek are suitable. The physical properties test is also suitable. For mechanical property testing, only samples from Gunung Bohong and Cipatik are suitable. Petrographic tests conclude that the three rock samples fit into the basaltic andesite rock category.

Effect of temperature and moisture composite environments on the mechanical properties and mechanisms of woven carbon fiber composites

AbstractTemperature and moisture are important environmental conditions governing the usage of carbon fiber‐reinforced plastics (CFRP). In this study, tensile, compression, and shear tests of woven CFRP composites were conducted in four composite environments: cold‐temperature dry state, room‐temperature dry state, elevated‐temperature dry state, and elevated‐temperature wet state. Fourier transform infrared (FTIR) spectroscopy was used to analyze the molecular composition and structure under these environments. The fracture morphology was also analyzed using scanning electron microscopy (SEM) to understand the deterioration mechanism of the material properties at the macro and micro scales. Finally, a two‐parameter Weibull statistical model was used to evaluate the scattering of the composites. The results demonstrate that the tensile, compressive, and shear properties of the material decrease under harsh conditions, and the degradation effect on the ultimate strength is much greater than that of the modulus. Cold‐temperature dry and elevated‐temperature wet conditions are particularly severe. Composite environments significantly affect the macroscopic failure process and ultimate failure mode of materials. In general, the temperature and humidity of the matrix system acts at the core of the deterioration mechanism of composites, affecting the properties of the fiber/matrix and orthogonal woven fiber interfaces, and eventually resulting in a loss of their constitutive strength and bearing capacity. The theoretical ultimate strength were consistent with the experimental values.Highlights Comprehensive mechanical property testing in multiple composite environments. Degradation mechanisms were revealed from multiscale morphology analysis. Scattering of composites were evaluated using statistical analyses. Cold temperature dry and elevated temperature wet were the worst states. Deterioration effect of environment on matrix and interface is the core failure mechanism.

Experimental Study on the Durability Performance of Sustainable Mortar with Partial Replacement of Natural Aggregates by Fiber-Reinforced Agricultural Waste Walnut Shells

Through the recovery and reuse of agricultural waste, the extraction and consumption of natural aggregates can be reduced to realize the sustainable development of the construction industry. Therefore, this paper utilizes the inexpensive, surplus, clean, and environmentally friendly waste agricultural material walnut shell to partially replace the fine aggregates in mortar to prepare environmentally friendly mortar. Considering the decrease in mortar performance after mixing walnut shells, basalt fibers of different lengths (3 mm, 6 mm, and 9 mm) and different dosages (0.1%, 0.2%, and 0.3%) were mixed in the mortar. The reinforcing effect of basalt fibers on walnut shell mortar was investigated by mechanical property tests, impact resistance tests, and freeze–thaw cycle tests. The damage prediction model was established based on the Weibull model and gray model (GM (1,1) model), and the model accuracy was analyzed. The experimental results showed that after adding basalt fibers, the compressive strength, split tensile strength, and flexural strength of the specimens with a length of 6 mm and a doping amount of 0.2% increased by 13.98%, 48.15%, and 43.75%, respectively, and the fibers effectively improved the defects inside the walnut shell mortar. The R²s in the Weibull model were greater than 87.38%, and the average relative error between the predicted life of the impacts and the measured values was greater than 87.38%. The average relative errors in the GM (1,1) model ranged from 0.81% to 2.19%, and the accuracy analyses were all of the first order.

Enhancement of strength-plasticity synergy in a graphene metallic glass composite

Metallic glass (MG) shows great potential for a wide range of functional and structural applications. However, it remains a challenge to enhance the ductility of metallic glasses without compromising their strength during development. A composite of bulk metallic glass/graphene (BMG/C(n)) was prepared using the suction casting method in argon atmosphere, with a nominal composition of (Zr60Ni20Al20)100-x(C(n))x (x = 5,10,15). The results indicate that the graphene well dispersed in the BMG matrix without any other intermetallic compounds present. Mechanical property testing reveals a significant increase in both plasticity and hardness with increasing graphene content, while maintaining high fracture strength of the BMG matrix.

Design of the CFC composite brazed HFS first wall on the NBI shine-through area of the EAST device

The high field side (HFS) first wall is the inner wall nearest to the vertical center axis in tokamak. To avoid high Z impurity sputtering due to plasma interaction and neutral beam injector (NBI) radiation, graphite is adopted as the plasma facing material (PFM) of the HFS first wall on the NBI shine-through area (NBISTA). In the experimental advanced superconducting tokamak (EAST), graphite tiles are bolted to the CuCrZr heat sinks by screw on the NBISTA, but cracks, fractures and ablations were observed on the graphite tiles after experimental campaigns because of insufficient heat removal capability. Thus, a new design of the HFS first wall on the NBISTA was proposed by adopting the carbon fiber composite (CFC) and brazing technology. In the new design, CFC tiles were brazed to the CuCrZr heat sink, and the oxygen-free copper (OFC) sheet was adopted between CFC tiles and CuCrZr heat sinks as stress-buffer layer. To avoid potential brazing failures or CFC tiles detachments, a modular pattern active cooling panels was proposed for the HFS first wall on the NBISTA. Steady heat transfer analysis of those panels was carried out and results show that the heat removal capacity satisfied the design requirements. Meanwhile, feasibility of the CFC brazing process was verified by nondestructive testing (NDT), mechanical property testing and high heat flux (HHF) testing, and testing results indicate that the CFC/OFC/CuCrZr bonding processed by one-step brazing had good mechanical property and heat removal capability.

Effect of BN interfacial layer on the mechanical behavior of SiC fiber reinforced SiC ceramic matrix composites

AbstractBoron nitride (BN) interfacial layer with controlled thickness and structure was prepared on the surface of near stoichiometric ratio SiC fiber preforms by a chemical vapor deposition process, and the SiC/SiC composites were obtained by polymer precursor infiltration and pyrolysis process. The microstructure of the BN interfacial layer and SiC/SiC composites was tested by scanning electron microscopy, and the mechanical behavior of SiC/SiC composites was characterized by a mechanical properties test. Results showed that BN interfacial layer was evenly distributed in the fiber preforms with excellent thickness consistency. As the thickness of the BN interfacial layer increased, the deflection path of the crack increased gradually, resulting in the flexural strength first increasing and then decreasing. The mechanical behavior mentioned above was mainly attributed to the dual effects of load transfer and crack propagation of the BN interfacial layer; that was, the crack propagation of ceramic matrix under external load lengthened the path of load transfer and formed a large number of fibers bridging and pulling out successively, which contributed to the energy dissipation mechanism.

Mechanical property tests and physics-informed data-driven modeling of viscoelastic materials subjected to thermal-oxidative aging

The purpose of this paper is to investigate and characterize the performance changes of viscoelastic materials (VEMs) in viscoelastic (VE) devices used for structure vibration control due to the influence of aggressive environmental conditions during long-term service. To this end, a series of thermal-oxidative (TO) aging experiments are conducted on the developed VEMs, variation of microstructure and macroscopic mechanical behaviors of TO aged VEMs are tested and analyzed. The molecular chain network of VEMs that can be simplified into elastic chain network and free chain network is described by the architecture of microsphere model, a physics-informed data-driven model is proposed to reflect the mechanical properties of TO aged VEMs, in which the physics-informed neural network (PINN) theory is incorporated to describe the statistical characteristics of molecular chains and the reaction rate of TO aging. Based on the experimental data, implementation and validation of the proposed model are conducted on the mechanical properties of VEMs under varying aging levels. The experimental results suggest that TO aging could alter molecular chain structure of VEMs from the microscopic level, leading to an increase in crosslinking degree and modulus, and the degeneration of deformation ability and energy-dissipation capacity for VEMs. The verifications reveal that the proposed model possesses high accuracy in characterizing the mechanical properties and energy-dissipation capability of VEMs under different aging levels, which preliminarily proofs the potential of PINN theory in reflecting the complex mechanical behaviors of VEMs.

Analysis of the Strength Properties of Epoxy-Glass Composites Modified with the Addition of Rubber Recyclate Using Kolmogorov-Sinai Metric Entropy.

This paper presents the results of investigations of the mechanical properties of epoxy-glass composites with the addition of rubber recyclate. For the purposes of the study, seven variants of materials were designed and manufactured, which differed in terms of the percentage of recyclate content (3, 5 and 7%) and the way the recyclate was distributed in the composite (one, two and three layers with a constant share of 5%). Tests of comparative mechanical properties were carried out using a static tensile test. As a result of the conducted tests, the following values were obtained for all variants of materials: tensile strength (Rm), Young's modulus (E) and percentage relative strain ε. In addition, for a deeper analysis of the results obtained, statistical calculations of Kolgomorov-Sinai EK-S metric entropy were performed on the experimental data sets, which were then analyzed. The results of the analysis indicate that the application of metric entropy calculations EK-S can be helpful in identifying changes in the internal structure of the composite material that occur during its loading, and which do not manifest themselves in any other tangible way. The data obtained as a result of the research can be used to optimize production processes and to determine the further direction of development of epoxy-glass composites with the addition of rubber recyclate, while saving time and resources.

Systematic Investigation of the Degradation Properties of Nitrile-Butadiene Rubber/Polyamide Elastomer/Single-Walled Carbon Nanotube Composites in Thermo-Oxidative and Hot Oil Environments.

The physical blending method was used in order to prepare nitrile-butadiene rubber/polyamide elastomer/single-walled carbon nanotube (NBR/PAE/SWCNT) composites with better thermal-oxidative aging resistance. The interactions between SWCNTs and NBR/PAE were characterized using the Moving Die Rheometer 2000 (MDR 2000), rheological behavior tests, the equilibrium swelling method, and mechanical property tests. The 100% constant tensile stress and hardness of NBR/PAE/SWCNT composites increased from 2.59 MPa to 4.14 MPa and from 62 Shore A to 69 Shore A, respectively, and the elongation decreased from 421% to 355% with increasing SWCNT content. NBR/PAE/SWCNT composites had improved thermal-oxidative aging resistance due to better interactions between SWCNTs and NBR/PAE. During the aging process, the tensile strength and elongation at break decreased with the increase in aging time compared to the unaged samples, and the constant tensile stress gradually increased. There was a more significant difference in the degradation of mechanical properties when aged in a variety of oils. The 100% constant tensile stress of NBR/PAE/SWCNT composites aged in IRM 903 gradually increased with aging time while it gradually decreased in biodiesel. The swelling index gradually increased with increasing SWCNT content. Interestingly, the swelling index of the composites in cyclohexanone decreased with the increase in SWCNT content. The reasons leading to different swelling behaviors when immersed in different kinds of liquids were investigated using the Hansen solubility parameter (HSP) method, which provides an excellent guide for the application of some oil-resistant products.

Effect of interfacial BeO content on microstructure and mechanical properties of beryllium/aluminum composites

In metal matrix composites, the existence of the interface phase imparts a complex influence on the interface bonding of the composites, while robust interfacial bonding is imperative for efficacious load transfer, which plays a crucial role in improving the mechanical properties of the composites. The purpose of this study is to investigate the effect of interface BeO content on the interfacial bonding strength and mechanical properties of Be/Al composites. Two types of Be/Al composites were prepared by self-exhausting pressure infiltration method, one of which was preheated in air atmosphere and the other was preheated under argon protection. Microstructural analysis results showed that significant oxidative corrosion occurred on the surface of beryllium particles in the Be/Al composite preheated in air atmosphere, and a considerable amount of oxide existed at the Be/Al interface, forming an oxide layer with oxide beryllium nanoparticles with particle sizes of 20∼50 nm. The interface of the Be/Al composite preheated under inert atmosphere was the direct combination of beryllium phase and the aluminum phase, with a few localized areas containing a small amount of aluminum oxide. Furthermore, mechanical property tests showed that the Be/Al composite preheated under inert atmosphere exhibited better mechanical properties and higher interfacial bonding strength. The first-principle simulation results further confirmed that the low interfacial bonding strength of the Be/Al composite preheated in air atmosphere was due to the much lower adhesion work of the BeO/Al interface than that of the Be/Al interface, and no bonding trend was observed between BeO and Al. The results of this study indicate that the presence of an abundance of interfacial BeO can lead to the deterioration of the Be/Al interface bonding, and avoiding the production of interfacial BeO is crucial in obtaining better interfacial bonding. These findings point out the direction for the design and preparation of high-performance Be/Al composites.

Microwave disinfection of facial silicone prostheses, part 2: Mechanical properties

Statement of problemPart 1 of this 2-part study determined that microwave disinfection did not degrade the color stability of facial silicone prostheses. However, investigations on the effects of microwave disinfection on the mechanical properties of different silicone elastomers are lacking. PurposeThe purpose of this in vitro study was to examine the mechanical properties of commonly used colored facial silicone elastomers before and after microwave disinfection over a simulated 1.5-year period. Material and methodsSix commonly used facial silicone elastomers: MDX4–4210, MDX4–4210/Type A, M511, A-2186, VST-50, and A-2000 were combined with functional intrinsic silicone pigments and opacifier (red, yellow, blue, and white). A total of 288 specimens were fabricated (n=12). Half of the specimens were tested for mechanical properties as the baseline, while the other specimens were tested after microwave disinfection. Microwave disinfection was performed with 660 W, 6 minutes of exposure time, and microwaved for 18 cycles to simulate 1.5 years of usage (one 6-minute exposure monthly). For mechanical property testing, all specimens were tested for tensile strength and percentage elongation (ASTM D412), tear strength (ASTM D624), and hardness (ASTM D2240). For each property, a 2-way ANOVA (silicone type and microwave disinfection factors) and Tukey multiple comparison test were performed using the R statistical software program (α=.05). ResultsFollowing microwave disinfection, tensile strength and percentage elongation of A-2000 increased significantly (P<.05). MDX4–4210, MDX4–4210/Type A, and A-2000 showed significant increases in their hardness (P<.001). Tear strength also increased significantly for MDX4–4210 and VST-50 (P<.05). Among the materials tested (ranked from highest to lowest value,=not statistically significant different), for tensile strength, VST-50>A-2186=A-2000>MDX4–4210/Type A=M511=MDX4–4210 (P<.05). For percentage elongation, VST-50>MDX4–4210/Type A>A-2186>M511=A-2000=MDX4–4210=M511 (P<.05). For hardness, A-2000=A-2186>M511=VST-50>MDX4–4210>MDX4–4210/Type A (P<.05). For tear strength, VST-50>A-2186>A-2000>M511>MDX4–4210/Type A=MDX4–4210 (P<.05). ConclusionsOverall, the mechanical properties of all the silicones tested were not adversely affected by microwave disinfection. VST-50 showed the best mechanical properties among the materials tested both before and after microwave disinfection. Microwave energy is a safe method of disinfecting the silicone elastomers tested in this study.

Rapid Alloy Development Using Calphad Simulation and Powder Blends in Direct Energy Deposition

The ongoing commercialization of additive manufacturing (AM) has necessitated the need to tailor alloy chemistry as well as exploit AM process particularities such as freedom of design, print geometry and high cooling rates to meet functional application requirements. Alloys such as hot-work tool steels, including H11, are well suited for machining and tooling applications. In this work, the authors investigated and compared high-speed direct energy deposition with laser beam source (HS DED-LB/M) processability of a reference H11 alloy and its modified form (H11m). The modification of the alloy was intended to minimize the amount of retained austenite (RA) in as-built microstructure and reduce post-heat treatment steps. The investigative approach included Calphad simulation, rapid alloy blending (modified powder) and process parameter optimization to produce dense parts for microstructure characterization and mechanical properties testing. The results show that while H11 achieved a high relative density &gt; 99.85%, H11m still had cracks parallel to the building direction. The amount of RA was equally reduced from 4.08% in H11 to 1.23% in the H11m. H11 had a comparatively superior average microhardness (591 HV0.5) to H11m (561.5 HV0.5), which can be attributed to the more carbide presence. The martensitic strengthening effect between H11 and H11m can be described as similar.

Effect of Vanadium Addition on Solidification Microstructure and Mechanical Properties of Al-4Ni Alloy.

The effects of vanadium addition on the solidification microstructure and mechanical properties of Al-4Ni alloy were investigated via thermodynamic computation, thermal analysis, microstructural observations, and mechanical properties testing. The results show that the nucleation temperature of primary α-Al increased with increased vanadium addition. A transition from columnar to equiaxed growth took place when adding vanadium to Al-4Ni alloys, and the average grain size of primary α-Al was reduced from 1105 μm to 252 μm. When the vanadium addition was 0.2 wt%, the eutectic nucleation temperature increased from 636.2 °C for the Al-4Ni alloy to 640.5 °C, and the eutectic solidification time decreased from 310 s to 282 s. The average diameter of the eutectic Al3Ni phases in the Al-4Ni-0.2V alloy reduced to 0.14 μm from 0.26 μm for the Al-4Ni alloy. As the vanadium additions exceeded 0.2 wt%, the eutectic nucleation temperature had no obvious change and the eutectic solidification time increased. The eutectic Al3Ni phases began to coarsen, and the number of lamellar eutectic boundaries increased. The mechanical properties of Al-4Ni alloys gradually increased with vanadium addition (0-0.4 wt%). The Al-4Ni-0.4V alloy obtained the maximum tensile strength and elongation values, which were 136.4 MPa and 23.5%, respectively. As the vanadium addition exceeded 0.4 wt%, the strength and elongation decreased, while the hardness continued to increase. Fracture in the Al-4Ni-0.4V alloy exhibited ductile fracture, while fracture in the Al-4Ni-0.6V alloy was composed of dimples, tear edges, and cleavage planes, demonstrating mixed ductile-brittle fracture. The cleavage planes were caused by the primary Al10V and coarse Al3Ni phases at the boundary of eutectic cells.

Design, modeling, and control of a novel soft-rigid knee joint robot for assisting motion

AbstractThis paper presents the design, modeling, and control of a novel soft-rigid knee joint robot (SR-KR) for assisting motion. SR-KR is proposed to assist patients with knee joint injuries conducting gait training and completing walking movements. SR-KR consists of a novel soft-rigid bidirectional curl actuator, a thigh clamping structure, and a crus clamping structure. The actuating part of SR-KR is composed of soft materials, which ensures the wearing comfort and safety, while the wearing parts contain rigid structure, which ensures the efficient transmission of torque. The bending deformation model of SR-KR is established, which reveal the relationship among SR-KR’s bending curvature, working pressure, and output torque. Experiments show that SR-KR can provide more than 26.3 Nm torque for knee joint motion in human gait range. A double closed loop servo control system including attitude servo and pressure servo is built to better apply SR-KR. Mechanical property test, trajectory-driven test, and lower limb wearing test have been conducted, which show that SR-KR has ability to assist in lower limb motion and has potential in the fields of rehabilitation and human enhancement.

A contrastive characterization of pure Mg and AZ91D alloy based on the testing of mechanical, corrosion, wear, and erosion properties

Abstract Magnesium alloy of grade AZ91D is utilized for a variety of applications in aircraft design and frames, as well as vehicle engine radiators, bumpers, and suspension components to reduce the weight of automobiles. This research compared the mechanical, corrosion, wear, and erosion resistance of pure Mg to that of AZ91 alloy. The corrosion media was NaCl, NaOH, and MgSO4, and the weight loss method was utilised to evaluate corrosion. The pin-on-disc configuration was utilized to assess the dry sliding wear mechanism of the Pure Mg and AZ91D alloy. Pure monolithic Mg and AZ91D magnesium alloy have a low resistance to wear as a result of an increase in contact temperature brought about by a shift of operational conditions. Erosive wear is caused when solid particles in a liquid or air jet strike a surface. Significantly influencing the erosive wear are particle velocity, impact angle, and erodent particle size. In this work, the erosive wear of AZ91D was studied using an Air jet erosion tester. SiO2 was used as the eroding material, and the flow rate of the eroding material and air was 5 gm min−1. The erosive factor experiments are designed using Taguchi orthogonal array (L16). The erosive factor response is erosion rate and primarily regulated by three factors as angle (30°, 45°, 60°, and 90°), time (5 and 10 min) and, contact pressure (1 and 2 bar). The results of the experiments showed that the rate of wear increased with increasing pressure, and that the angle of impact of the jet at 60° caused the most wear of any of the tested angles. Analysis of variance (ANOVA) shows that time is the most important factor in determining erosive rate for AZ91D. SEM is used to investigate the structure and morphology of worn-out materials, and its findings are then confirmed.

Failure Analysis of S55C Medium Carbon Steel for the Pickup Crankshaft

There have been reports from service centers of important problems of a diesel engine crankshaft in mini trucks. All crankshafts crack from the same region, the fracture occurred in the first crankpin of the crankshaft. The crankshaft is made from JIS-S55C hardened medium carbon steel. A series of experiments including chemical analysis, macro and microstructural analysis, mechanical properties test, and numerical stress analysis. The results of fracture surface of this crankshaft were cause by fatigue with the detection of beach marks, ratchet marks, river marks, cleavage fracture and fatigue striations which these results indicate that the fracture mode of brittle fracture. The microstructure is composed of perlite-ferrite on the outer surface showed some coating nitriding layers, most hard coating is not found, the hardness test revealed an uneven hardness distribution, the maximum hardness on the center of the shaft measuring 309 HV, which is more than compared to the outer surface is 259 HV for these applications. It was found that the hardness value was abnormal. This is consistent with the experimental results of the surface microstructure which showed some coating layers, while the hard coating is not found. Besides, the numerical results also revealed that the first crankpin fillet was the most vulnerable to breakage, which is consistent with the mechanical experimental results. Finally, the summary analysis results are consistent with the hypothesis of this research and as an information for a prevent such failures crankshaft in the future.