Transverse Strength Research Articles

Effects of Longitudinal Alternating Magnetic Field on the Microstructure and Properties of CMT-WAAM Al-5%Mg Alloy

The major challenges in wire arc additive manufacturing (WAAM) of aluminum alloys include improving the forming quality, reducing pore and crack defects, and optimizing the overall mechanical properties. In this study, an external longitudinal alternating magnetic field (LAMF) was applied to assist cold metal transfer (CMT) WAAM process of Al-5%Mg alloy. This study compared the effects of different LAMF intensity parameters on the electrical behavior, molten droplet transition, macroscopic forming, microstructure and mechanical properties of CMT-WAAM multi-layer thin-walled structures. Compared with the situation without the alternating magnetic field, the application of an external LAMF could cause the arc to expand and rotate, deflect droplets and stir the molten pool periodically. When the alternating magnetic field parameters were set at a current of 3A and frequency of 100Hz with magnetic field intensity of 9mT, the deposited samples achieved macroscopic forming with superior surface quality and geometric accuracy, and the internal defect rate was reduced from 0.742% to 0.168%. Also, the mean grain size of the deposited layer was reduced from 186μm to 154μm, and the average hardness was increased from 68.1HV0.2 to 91.1HV0.2 with an improvement rate of 33.7%. Moreover, the longitudinal tensile strength was increased from 249 MPa to 257 MPa, the transverse tensile strength was increased from 264 MPa to 273 MPa, and the yield strength and elongation at break were both increased. This study demonstrates theoretical guidance for enhancing the component overall performance of aluminum alloy LAMF-WAAM technology.

Test methods for determination of shear properties of sandwich panels

This paper presents analysis and comparison of test methods for determining transverse shear strength and shear modulus of steel-faced sandwich panels commonly used in construction. The test methods are taken from the governing European standard EN 14509:2013. Two-point loading and four-point loading test methods as well as a full-scale test method are examined. Based on extensive experimental work on sandwich panels with varying core thickness, comprising mineral wool (MW) and polyisocyanurate (PIR) and encompassing both roof and wall panels, this study provides details of the test setup for the four-point loading and vacuum box methods with which a pure shear failure is obtained. Such details are missing from EN 14509. This paper highlights that the two-point loading method fails to consistently produce shear failure, especially in thicker panels, indicating it does not accurately measure transverse shear strength. The results of the experiments conducted in this study indicate that the four-point loading and full-scale test methods provide consistent shear failure for thicker panels while yielding greater transverse shear strength than the two-point loading test in general.

The influence of the addition of titanium oxide nanotubes on the properties of 3D printed denture base materials.

In this study, the effects of adding titanium dioxide nanotubes (TiO2) to 3D-printed denture base resin on the mechanical and physical properties of denture bases were examined for the first time. The specimens were digitally created using 3D builder software from Microsoft Corporation through computer-aided design. In accordance with the test specifications for transverse strength, impact strength, hardness, surface roughness, and color stability, specimens were designed and printed with certain dimensions following relevant standards. TiO2 nanotubes (diameter: 15-30 nm and length: 2-3 μm) were added to the 3D-printed denture base resin (DentaBase, Asiga, Australia) at 1.0% and 1.5% by weight. Flexural strength, impact strength (Charpy impact), hardness, surface roughness, and color stability were evaluated, and the collected data were analyzed with ANOVA followed by Tukey's post hoc test (α = 0.05). Field emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDX) mapping were used to evaluate the dispersion of the nanotubes. Compared with those of the control group (0.0 wt.% TiO2 nanotubes), the average flexural, impact, and hardness values of the 1.0 and 1.5 wt.% TiO2 nanotube reinforcement groups increased significantly. Both nanocomposite groups showed significant color changes compared to that of the pure resin, and there was a considerable reduction in the surface roughness of the nanocomposites compared to that of the control group. Adding TiO2 nanotubes to 3D-printed denture base materials at 1.0 and 1.5 wt.% could enhance the mechanical and physical properties of the material, leading to better clinical performance. In terms of clinical applications, 3D-printed denture base material has been shown to be a viable substitute for traditional heat-cured materials. By combining this with nanotechnology, existing dentures could be significantly enhanced, promoting extended service life and patient satisfaction while addressing the shortcomings of the current standard materials.

Simultaneous enhancement of axial/transverse compressive strength of aramid fibers by the construction of branched multi-hydrogen bonding sites

The terrible compressive strength is a prominent issue that restricts the broad application of organic fibers in multi-dimensional stress scenarios. Traditional strategies focus on enhancing the axial compressive performance of fibers, simultaneously improving the axial and transverse compressive properties of fibers still poses significant challenges. Inspired by the octopus's tentacles that can conduct stress in multiple directions, a novel strategy by constructing branched multi-hydrogen bonding sites structure in aramid fiber was conducted to solve the problem. The branched multi-hydrogen bonding sites constructed on nano-silica (SiO2–B) offer excellent dispersibility within the poly(p-phenylene-benzimidazole-terephthalamide) (PBIA) matrix. Composite fibers (PBIA-SiO2-B) co-mixed with SiO2–B and PBIA were prepared using a solution spinning technique. The results of Fourier-transform infrared spectroscopy (FTIR) and dynamic mechanical analysis (DMA) reveal that the introduction of SiO2–B significantly enhances the intermolecular interactions within the composite fibers, and this enhancement mechanism has been elaborately elucidated through molecular simulations. Furthermore, finite element simulations confirmed that the incorporation of branched structure exhibits enhanced stress-bearing capabilities under multi-directional stress and offers outstanding support when subjected to transverse compressive stress compared to linear molecular chains. Hence, compressive property testing revealed that the PBIA-SiO2-B composite fibers achieved axial compressive strengths and transverse compressive strengths of 714.3 MPa and 305.8 MPa, respectively, representing increases of 68.8 % and 26.8 % over pure PBIA fibers. Moreover, with the enhancement of transverse compressive strength, the Young's modulus and interfacial shear strength of PBIA-SiO2-B fibers were also increased by 7.1 % and 20.9 %, respectively.

Synthesis and characteristics of natural fiber reinforced nano hybrid composite – an experimental study

Abstract Recently, research on natural hybrid composites has occupied a significant role in the materials science sector. Due to the low density, high specific strength, dimensional stability, and biodegradability, natural fiber composite has become a predominant research area. The present study deals with the fabrication of a jute–banana fiber hybrid composite using the hand layup method with compression molding. A fixed concentration of 5 % carbon nanotubes (CNT) is included over the fiber surfaces as an additional reinforcement material to improve their thermal and electrical conduction properties. The prepared composite material is subjected to different fiber loading (0, 10, 20, and 30 wt.%) with jute and banana weight ratios of 1:1, 1:3, and 3:1. The investigation is conducted for testing the physical, mechanical, and thermal properties of the prepared composites along with morphological studies. Final results revealed a maximum longitudinal tensile strength of 68.8 MPa, 67.0 MPa, and 86.7 MPa and the maximum transverse tensile strength of 41.2 MPa, 40.5 MPa, and 48.0 MPa at 30 wt.% with respective fiber ratio of 1:1, 1:3, and 3:1. The maximum longitudinal flexural strength of this hybrid composite is noticed as 94 MPa, 90 MPa, and 103 MPa for the weight ratio of 1:1, 1:3, and 3:1. Higher impact energy is obtained for the composition ratio of 1:3 (JBC 1:3) which has more banana fiber than the other two. A new attempt at adding carbon nanotubes has improved their thermal conductivity compared to regular composites of jute–banana.

Pengaruh Penambahan Kitosan Nano Gel Bermolekul Sedang pada Bahan Basis Gigi Tiruan Resin Akrilik Polimerisasi Panas Terhadap Kekuatan Transversal

Hot polymerized acrylic resin is one of the most widely used denture base materials, but this material has low transverse strength so it is easy to fracture. Transverse strength can be increased by adding reinforcing material Chitosan nano gel which is proven to increase transverse strength because the Chitosan nano gel has special properties such as biodegradability, biocompatibility, good mechanical properties and good layer formation properties. The purpose of this study was to determine the effect of adding Chitosan nano gel to heat polymerized acrylic resin denture base material on the transverse strength. The research design used in this study was an experimental laboratory. The research sample was a rectangular hot polymerized acrylic resin with a size of 65 mm x 10 mm x 2.5 mm±0. 5 for the calculation of transverse strength with a total sample of 27 samples. The results of this study indicate that the value of transverse strength added with 1.25% Chitosan nano gel is the most effective concentration to increase the transverse strength of the heat polymerized acrylic resin denture base material compared to the addition of 1% Chitosan nano gel and without the addition of chitosan nano gel.

Effect of Cr3C2 Addition on Microstructure and Mechanical Properties of WC-CoNiFe Cemented Carbides

In traditional cemented carbides, Co is mainly used as a binder. Recently, replacing Co with medium- to high-entropy alloys has shown significant improvements in hardness, fracture toughness, high-temperature oxidation resistance, and corrosion resistance, making it a research focus globally. Both the typical grain refiner Cr3C2 and medium- to high-entropy alloy binders affect the WC grain size in cemented carbides. This study investigates the synergistic grain refinement mechanism of Cr3C2 and medium- to high-entropy alloy binders on WC grains and their impact on the microstructure and mechanical properties of cemented carbides. The results show that increasing the Cr3C2 addition refined WC grains in the WC-CoNiFe alloy, increased coercivity, and enhanced hardness, with transverse rupture strength first increasing and then decreasing. The alloy achieved optimal performance at 0.6 wt.%Cr3C2, with a hardness of 91.25 HRA and transverse rupture strength of 3883.2 MPa.

Effect of hollow glass microspheres on transverse properties of carbon fiber reinforced epoxy composites

AbstractHollow glass microsphere (HGM)—based composites are gaining popularity in materials research due to their ability in altering material characteristics drastically. The current study investigates HGMs filled carbon fiber reinforced epoxy (CE) composites on transverse properties, aiming for aerospace and defense applications mainly in composite pressure vessels. Unidirectional laminates of Carbon/Epoxy with varying HGM percentages (0.2, 0.4, 0.6, 0.8, 1.0 wt. %) were wounded onto a flat‐plate mandrel using a 4‐axis filament winder, along with a baseline sample without HGM for comparison. The glass transition temperature (Tg) and thermal stability were analyzed by carrying out dynamic mechanical analysis and thermogravimetric analysis. The fracture mechanism of the samples loaded under tension was investigated using FESEM. Experimental results indicate reduction in density with increase in HGM content, up to 0.4% HGM there is increase in transverse tensile strength of 25% compared to baseline and further increase in HGM content, decrease trend is observed. 30% decrease in transverse compressive strength is observed compared from baseline to 1.0 wt. % of HGM. No significant change was noticed in the thermal stability and Tg on introduction of HGM. Microscopy images of fractured samples revealed effective physical interaction and dispersion of the HGM within the matrix.Highlights Transverse mechanical properties are tested to know the influence of HGM filler on filament wound composites. Density of the composite decreases with increase in HGM content. Thermal stability and Tg shows less change on introduction of HGM in composites.

Evolution of microstructure and mechanical properties of TiB2-7.5 wt.% WC-based cermets sintered at different temperatures

The evolution of microstructure and mechanical properties of TiB2–7.5 wt% WC-based cermets sintered at different temperatures were investigated. The results showed that eutectic liquid phase appeared at around 1335 °C, indicating that solid-phase sintering occurred below that temperature, while liquid-phase sintering occurred above that temperature. TiB2, W2CoB2, WB and CoNi phases were detected in the XRD patterns of cermets sintered at different temperatures, and TEM analysis showed the presence of TiC phase. So the following chemical reaction should occur: TiB2 + WC + Co → W2CoB2 + WB + TiC. The TiB2 core - (Ti, W, Co, Ni)(B, C) rim phase were observed in the cermet sintered at 1397 °C. As the increase of sintering temperature, the solubility of WC and TiB2 in CoNi binder phase, and the number of core-rim structure hard phase particles increased. The formation of core-rim structure enhanced the interfacial bonding strength between TiB2 phase and CoNi binder, which was beneficial for improving the strength and toughness of cermets. The cermets sintered at 1465 °C had good comprehensive mechanical properties, with a relative density of 99.62%, a hardness of 17.34 ± 0.43 GPa, a transversal rupture strength of 2038 ± 53 MPa, and an indentation fracture toughness of 12.15 ± 0.32 MPa·m1/2.

Upper and Lower Bounds to Pull-Out Loading of Inclined Hooked End Steel Fibres Embedded in Concrete

Steel fibre-reinforced concrete (SFRC) consists of short, hooked steel fibres that are randomly distributed and oriented within the cementitious matrix. This paper presents a new analytical load-bounding approach that captures the tensile response of misaligned fibres embedded in the matrix. The contribution of fibres in bridging cracks to provide the required stress transfer relies on the orientation of the fibres in the concrete. Bridging fibres aligned with a crack are less effective than those inclined to it. Therefore, understanding the pull-out behaviour of misaligned fibres is a key factor in quantifying and optimising the design of SFRC in structural applications. In the laboratory, a single-oriented fibre embedded in a solid cylinder of concrete was subjected to a pull-out test, where the axis of the tensile force is aligned with the axis of the cylinder. Based on the observed behaviour, this paper presents a new analytical bounding approach to capture the pull-out response of misaligned hooked-end steel fibres embedded in a concrete matrix. The analysis was based on a transversely isotropic failure criterion assumed for the plasticity that occurs in the cold-drawn fibre. Lower and upper bounds to the loading failure were derived from fibre pull-out and fibre fracture, respectively. The division between bounds depended upon the fibre orientation, fibre diameter and the combined strengths of the steel and concrete. Bounding predictions were drawn from ratios between a fibre’s shear strength and its transverse and axial uniaxial strengths, as found from a novel testing proposal. The two bounds were compared with new data and other experimental results published in the literature. The results showed that the region between the bounds captured the failure loads of embedded fibres with effective load-bearing orientations. A critical orientation was observed at maximum strength. The present interpretation of the plasticity occurring within off-axis, hooked-end steel fibres suggests that it is possible to optimise the strength of concrete using this method of reinforcement.

Error analysis for determining transverse tensile delamination strength of REBCO coated conductors by anvil test: numerical simulation demonstrations

RE–Ba–Cu–O (REBCO, where RE = Y, Gd, Sm, and other rare earth elements) coated conductor (CC) tapes exhibit considerable potential for application within the domains of high-energy physics and high-field science. Nevertheless, weak interfacial properties pose a significant obstacle, impeding the progress and practical implementation in high-field scenarios. The anvil tension method has been extensively employed for the assessment of transverse delamination strength of REBCO CC tapes. However, the outcomes derived from anvil tension exhibit severe dispersion, thereby impeding its efficacy in evaluating material performance. The underlying cause of this phenomenon remains unidentified. In this study, error analysis of anvil measurement method in determining the transverse tensile delamination strength (TTDS) of REBCO CC tapes was conducted based on finite element (FE) numerical simulations. A two-dimensional multilayer elastic-plastic delamination FE model with main layers of REBCO CC tapes, solder connecting layers and anvil materials were developed based on the bilinear cohesive zone model. The effects of anvil test conditions and the structural configuration of the conductor itself on the test results were discussed. Simulation results show that localized premature cracking of the interface due to stress concentration and plastic yielding of the CC tape around the loading boundary is the root reason for the discrepancy between the anvil test results and the true interfacial strength. Therefore, anvil test conditions (including top anvil dimensions, soldering conditions, loading eccentricity angle, and anvil material properties) as well as the structural configuration of the conductor itself (including edge initial crack length, edge encapsulation width, and stabilizer thickness) have a significant impact on anvil test-based TTDS results.

Anisotropy of microstructure features and tensile properties of Ti–48Al–2Cr–2Nb alloy produced by electron beam powder bed fusion

A Ti–48Al–2Cr–2Nb alloy was produced by electron beam powder bed fusion. The effect of the volume energy density parameter on the forming quality was investigated, and the tissue characteristics, hardness distribution, and mechanical properties of the alloy were analyzed. The results showed that the quality was better when the volume energy density parameter was 21.5–22.5 J/mm3. The microstructure of the alloy has the phenomenon of changing with the forming height: with an increase in the forming height, the forming part produces the phenomenon of strip microstructure along the construction direction, and the regional microstructure variability occurs under the cross section of the same height. The average hardness of the alloy reached 375.2 HV at the bottom, 381.8 HV in the middle, and 389.6 HV at the top, and the standard errors of the hardness values were 12.40, 10.49, and 7.12 HV, respectively, with the microhardness showing a gradual increase along the molding direction, and the homogeneity was gradually better. The transverse tensile strength at room temperature reached 526 MPa, the yield strength reached 461 MPa, and the elongation at break reached 1.24%, while the longitudinal tensile strength reached 486 MPa, the yield strength reached 414 MPa, and the elongation at break reached 1.02%.

Microstructure, mechanical, and cutting performance properties of B4C and SiC reinforced sandwich composite segments

This study aims to extend the work-life of diamond-cutting segments and to economize the operating cost of diamond-cutting tools. In order to achieve this object, bronze matrix sandwich segments reinforced with SiC and B4C were produced utilizing the hot pressing technique. In the term of the cutting segments, it is favorable that the outer layers are wear-resistant and the middle layer is tough. SEM and XRD analysis were used to determine the microstructural properties. Mechanical properties were evaluated by conducting hardness, wear, cutting performance, and three-point bending tests. The cutting performance of the segments was determined by turning andesite marble. SEM examinations showed that SiC and B4C grains were homogeneously distributed in the bronze matrix. The highest hardness value was 113.9 HB in the B4C reinforced sandwich segment. The reciprocating wear test findings indicated that the matrix exhibited the lowest wear rate in the B4C reinforced sandwich composite segment, followed by the hybrid sandwich composite segment. The lowest amount of cutting loss after turning andesite stone was achieved in the SiC, and B4C reinforced hybrid sandwich composite segment. The cutting performance of the hybrid sandwich composite segment increased by 46.15 % compared to the conventional segment without additives. The highest value of the transverse rupture strength of the specimens was 380 MPa for the B4C reinforced sandwich composite segment and 352 MPa for the hybrid sandwich composite segment. Considering all the tests and analyses, the hybrid sandwich composite segment sample may be the most suitable for diamond-cutting tools.

Controlled Interlayer Binding and Healing Improve the Transverse Properties of Upcycled Disposable Waste Wood.

Recovery and reuse of bulk waste wood are particularly challenging because of usage defects and contaminations. Here, we present a robust and efficient strategy for regenerating used wood veneers into high-performance structural materials through micro/nano interface manipulation. Our approach involves using cellulose-based interlayers to bind together two waste wood plates without an external adhesive by partially dissolving and regenerating the interlayer using a solution of ionic liquids and dimethyl sulfoxide. The mechanical properties of the regenerated wood exceed that of natural wood, displaying over a 16 and 20 times increase in transverse tensile strength and modulus, respectively, and 4-6 times improvement in longitudinal tensile strength and modulus. Nanoscale mechanical analyses show that the improvement is possible as a result of several factors, including the robust network structure of the interlayer, the good adhesion at the wood-interlayer interface, the compacted wood structure, and the low stiffness and deformation gradients between the interlayer and the wood structure. The interlayers can be created from waste papers and wood particles by taking advantage of the nanofibrillar structure of cellulose.

Enhancement of mechanical properties of NbCN-Ni cermets via WC addition

In this study, the microstructural and mechanical properties of sintered NbCN-Ni cermets with various WC contents were investigated. The density and grain size of the NbCN-Ni cermets increased with an increase in the sintering temperature from 1420 to 1510 °C, whereas after WC addition, the average grain size of NbCN decreased significantly. The added WC was initially dissolved in the binder phase and then dissolved in NbCN crystals and formed a white W-rich (Nb,W)CN shell phase and gray Nb-rich (Nb,W)CN core phase structure for WC contents up to 10 wt%. Meanwhile, the formation of the shell-core structure enabled the morphology of NbCN grains to gradually change from polygonal to spherical, which can be attributed to the high solubility of WC in the Ni binder. The hardness and transverse rupture strength (TRS) of the cermets first increased and then decreased with increasing sintering temperature and WC content. At a WC content of 10 wt% and sintering temperatures of 1480 and 1450 °C, the HV10 and TRS of the cermets reached maximum values of 1405 kg/mm2 and 1280 MPa, respectively. The friction coefficient of the NbCN-Ni cermets decreased from 0.7 to 0.55–0.6 after WC addition. Hence, the cermets exhibited excellent wear resistance because the introduction of WC decreased their friction coefficient and increased their hardness.

A Comparative Study on the Wear Performance and High-Temperature Oxidation of Co-Free Cermets and Hardmetals.

The present investigation addresses the mechanical properties, wear behaviour, and high-temperature oxidation of cermets and hardmetals based on either Ti(C,N) or WC and a metal binder based on Fe15Ni or Fe15Ni10Cr. This study also includes a commercial-grade WC-Co for comparative purposes. The production of these materials involved a powder metallurgy and sinter-HIP processing route under identical conditions. It is found that WC-based materials have superior mechanical properties, including hardness, fracture toughness, transversal rupture strength (TRS), and wear response, compared to Ti(C,N)-based materials. However, the latter show better oxidation behaviour than the former. Notably, WC-FeNi exhibits a higher hardness and TRS than the commercial-grade material (an increase of 7% and 9%, respectively). The difference in wear behaviour is due to the difference in wear mechanisms. In this regard, cermets wear through a tribolayer of Ti and Fe oxides, while hardmetals primarily wear through abrasion from ploughing. Thus, hardmetals exhibit a lower coefficient of friction (COF) and wear rate than cermets. Furthermore, Ti(C,N)-based materials form a protective layer of TiO2, which enhances their integrity and reduces mass gain. The addition of Cr to the FeNi binder only appears to have a clear effect on the TRS of the materials.

A new modified direct method for determining the mode I delamination traction-separation law

A new equation was developed for the crack-tip separation in the double cantilever beam (DCB) specimen, which has been standardised for mode I delamination of composites. The very simple closed-form equation is based on a pseudo-elastic beam model and on the effective crack concept. Moreover, it only requires the common load–displacement data up to crack initiation and easy to obtain elastic moduli. Strain-energy release rate versus crack-tip separation curves can then be differentiated for obtaining the tractions, as in the classical direct method. Numerical results for piecewise linear traction-separation laws (TSL) showed good accuracy of strain-energy release rate versus crack-tip separation curves predicted. Application to two carbon/epoxy materials gave very promising TSL results, including cohesive strengths similar to transverse tensile strengths and post-peak steep traction decreases.

Effects of sintering method and Al2O3 content on microstructure and mechanical properties of WC-10Co cemented carbide

Ultra-high toughness and ultra-high hardness WC-10Co-xAl2O3 cemented carbides were successfully prepared by vacuum liquid phase sintering (VS) and spark plasma sintering (SPS) using ultrafine WC and commercial Co powders as raw materials, respectively. The effects of nano-Al2O3 content and sintering process on the relative density, average grain size, microstructure and mechanical properties of WC-10Co alloys were investigated. The results showed that the densification degree of the samples decreased with the increase of Al2O3 content. In addition, the relative densities of the samples prepared by SPS were lower than those of the samples prepared by VS. For the samples prepared by VS, the average grain size increased first and then decreased as the Al2O3 content increased from 3 wt% to 9 wt%, and the percentage of coarse grain showed the same trend. When the addition of Al2O3 was 6 wt%, the average grain size reached the maximum value of 1.39 ± 1.03 μm. Meanwhile, the sample with 6 wt% Al2O3 had a typical inhomogeneous dual-grain structure, and the percentages of fine grain (< 1 μm) and coarse grain (> 1 μm) were about 50%, which displayed the highest fracture toughness of 18.59 MPa·m1/2. The dual-grain structure not only improved the toughness, but also compensated the loss of hardness. However, for the samples prepared by SPS, with the increase of Al2O3 content, the average grain size of WC decreased, while both hardness and toughness were continuously improved. When the Al2O3 content increased to 9 wt%, the grain size reached the minimum value of 0.25 ± 0.08 μm, and meanwhile, the hardness and toughness reached the maximum value of 19.69 GPa and 12.29 MPa·m1/2, respectively. Moreover, as the Al2O3 content increased, the transverse rupture strength (TRS) of the samples prepared by VS increased first and then decreased, and the TRS of sample with 3 wt% Al2O3 reached the maximum value of 1410 MPa. However, the TRS of the sample prepared by SPS showed a decreasing trend.

Fracture and Wear Behavior of Functionally Graded 316L–TiC Composite Fabricated by Selective Laser Melting Additive Manufacturing

Herein, the tribological and fracture behavior of multilayer 316L–TiC composites produced by the selective laser melting additive manufacturing process is investigated. The results show a robust interface between the layers and no cracks are detected even after a flexural strain of 0.4. The hardness of the composite layers with 5 and 10 wt% TiC increases by 75.5 and 104.8% compared to the hardness of the pure 316L stainless steel layer. Transverse rupture strength measurements show that a layer of pure 316L significantly improves the rupture strength of the multilayer samples. Wear test results show that the inclusion of TiC particles increases wear resistance, with the composite layer containing 10 wt% TiC demonstrating the highest wear resistance.

Process optimization of continuous aramid fiber reinforced PA12 filaments and printed composites

AbstractA multi‐stage fiber spreading process for the preparation of high‐performance continuous aramid fiber reinforced nylon 12 (CAF/PA12) composites was proposed in this paper. The effects of spreading rod crown radius, spreading rod axis height and traction speed on fiber impregnation effect and filaments properties were investigated. The fiber volume fraction of the prepared filament was approximately 30%. And the maximum tensile strength and modulus of the filaments were 839.89 MPa and 41.35 GPa, which were 34.36% and 34.30% higher than unspreading filaments, respectively. The influences of printing process parameters such as printing temperature, the combination of layer thickness and printing spacing on the transverse tensile properties of the specimens were studied. Printed specimens reached a transverse tensile strength and tensile modulus of 13.988 MPa and 1.293 GPa, respectively. The influences on low velocity impact properties of the specimens were also investigated in terms of impact energy and printing stacking sequences. Results revealed that the impact threshold energy of orthotropic ([0/90/0/90]2) specimens was 50 J. Quasi‐isotropic ([0/45/90/−45]2) specimens exhibited the superior impact resistance with an impact load of 4.939 kN. Macro‐ and micro‐matrix crack, surface buckling, fiber fracture and delamination were the main failure modes of the specimens.Highlights A novel thermoplastic composite filament forming process was proposed, and the filament forming equipment was designed and manufactured. Continuous aramid fiber‐reinforced PA12 filaments with about 30% fiber content were prepared by orthogonal tests under different forming process conditions, which showed maximum tensile properties of 839.89 MPa and 41.35 GPa, respectively. Spreading multiplication was positively related to filament tensile properties, which was major affected by the axial height of the spreading rod. Transverse tensile strength (13.988 MPa tensile strength and 1.293 GPa tensile modulus) of printed specimens was investigated under different printing parameters. Fiber orientation had a significant effect on the low‐velocity impact properties. Micro‐ and macro‐matrix crack, surface buckling, fiber fracture and delamination were the main failure modes of the low‐velocity impact specimens.