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The heterogeneous magnesium (Mg) matrix nanocomposite with dispersed soft phase exhibits high strength and toughness. Herein, the deformation behavior and failure process were investigated to reveal the unique mechanical behavior of the heterogeneous microstructure under compression. The extensive plastic deformation is accompanied by the flattening and tilting of the soft phase, inhibiting strain localization and leading to strain hardening. Moreover, a stable crack multiplication process is activated, which endows high damage tolerance to the heterogeneous Mg matrix nanocomposites. The final failure of the composite is caused by crack coalescence in the shear plane along a tortuous path. The presence of dispersed soft phases within the hard matrix induces a noticeable change in mechanical response. Especially, the malleability of the heterogeneous Mg matrix nanocomposite is two and ten times higher than that of pure Mg and the homogeneous Mg matrix nanocomposite, respectively. The current study provides a novel strategy to break the trade-off between strength and toughness in metal matrix nanocomposites.

A powder thixoforging route combined with slurry based mixing process was proposed to fabricate graphene nanoplatelets (GNPs) reinforced magnesium matrix composites (MgMCs). The originally spherical and ball-milled ZK60 powders were used as matrices, respectively. The mixing of 0.05 wt.% GNPs with the spherical powder led to GNPs clusters and degraded the mechanical properties of the composite. In contrast, with the addition of an optimal content (0.1 wt.%) of GNPs, the composite fabricated from ball-milled powder achieved a joint enhancement in tensile yield strength (52%) and fracture toughness (19%), demonstrating a pronounced strengthening efficiency of 650% and a good balance between strength and toughness. The ball-milled powder endowed the composite with a homogenous distribution of GNPs and a denser microstructure with reduced Mg-Zn eutectics, and the thixoforging process offered a well-bonded Mg/GNP interface, making full use of the strengthening and toughening potential of GNPs. Theoretical predication based on a modified shear-lag model suggested that load transfer dominated the strengthening mechanisms. In-situ tensile tests verified that crack deflection, secondary cracks and GNPs bridging mainly accounted for the toughening mechanisms. A numerical model with consideration of GNPs orientations was also established to understand the toughening effect from GNPs bridging.

In this work, five types of combed cotton spun yarn, selected from tex 7.38, 5.95, and 4.22, with a twist factor ∝ t = 4300 (tex system), were manufactured via alternative spinning methods (ring and compact). These yarns were processed from Egyptian extra-long staple cotton: G45, G93, G88, G92, and Pc (a) (a promising crossed type). In addition, yarn of tex 7.38 (compact) was produced from long staple cottons G86 and Pc (b) (another promising crossed type). The other two yarns from the five type of yarns selected from tex 15 and 20, ∝ t = 3600 , were spun combed and carded ring only via using Egyptian cotton (medium long staple), G80, G90, and Pc (a) (a promising crossed type). Each yarn tex was processed from any of the latest types of Egyptian cotton, using experimental methods of measurement, which are different from the usual methods used. Yarn diameter was calculated using the Pierce formula. Yarn circular cross-section area (CSA) was determined and consequently the yarn breaking strength in mega Pascal [Mpa] was counted. Also, the toughness of each yarn was estimated. All these calculated values, for the different yarns, made from upgraded Egyptian cotton, were tabulated, sampled, graphed, and analyzed. The range of the yarns’ breaking strength was found to be from 244 (G45) to 231 (Pc(a)), their breaking extension changes were from 5.41% (G45) to 4.68% (Pc(a)). Consequently, their toughness varied from 6.6 Mpa (G45) to 5.41 Mpa (Pc(a)). Textile materials are part of material science, which uses engineering units to address the global market. This improves market tolerance of new products suitable for the inherent properties expressed in engineering units. These engineering units help the global spread of these new products, where they are applicable and practically reliable. To make the Egyptian cotton industry more known globally, there are several methods; one of them is the use of engineering units to facilitate its use and application. Therefore, the present work will participate partially in spreading our textile industry to the global market.

More translucent dental zirconias have been developed by incorporating the cubic phase and reducing the tetragonal phase content that undergoes transformation toughening, leading to reduced mechanical properties. Whether the clinically relevant mechanical property of the edge chipping toughness of the material is also reduced is unclear.The purpose of this in vitro study was to evaluate the edge chipping toughness and translucency of translucent zirconia, 3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), and lithium disilicate.Two translucent zirconia products, Katana and Lava Esthetic; one 3Y-TZP, Lava Plus; and one lithium disilicate, IPS e.max Press were prepared and tested for phase composition via X-ray diffraction (XRD) (n=3), translucency via a spectrophotometer (n=20), and edge chipping via a universal testing machine with a custom-machined specimen holder and diamond indenter (n=20). The 3Y-TZP and lithium disilicate served as the optimal control materials for edge chipping and translucency, respectively. Translucency was compared with 1-way ANOVA and edge toughness with ANCOVA (α=.05).The XRD showed the 3Y-TZP to be almost completely tetragonal phase compared with the 2 translucent zirconia products that were predominantly cubic. Katana UTML and IPS e.max Press had a statistically similar (P.05) translucency that was significantly (P.05) greater than that of Lava Esthetic and Lava Plus. The edge toughness of Katana UTML was 304 N/mm, IPS e.max Press was 354 N/mm, Lava Esthetic was 394 N/mm, and Lava Plus was 717 N/mm, with significance rankings of Katana UTMIPS e.max Press=Lava EstheticLava Plus.Some translucent zirconias had translucency similar to that of lithium disilicate; however, as translucency increased with increased cubic content, edge toughness decreased.

In order to improve the intrinsic brittleness of TiAl alloys, Ti2AlNb alloys with outstanding ductility and toughness at room temperature, and good high-temperature performance are competitive candidates in constructing the TiAl-based laminated composites. In this work, TiAl/Ti2AlNb laminated composites are successfully synthesized by vacuum hot pressing combined with the foil-foil (sheet) metallurgy. Under the pressure of 65 MPa, different holding time and temperature of hot pressing are tried and the optimized fabrication parameter is acquired as 1050 °C/120 min/65 MPa. Along with the changes of processing parameters, the defect, microstructure, interface, phase transformation and the corresponding mechanical properties are detailly discussed. The results show that the TiAl/Ti2AlNb laminated composite fabricated at 1050 °C for 2 h achieves a good metallurgical interface bonding. The corresponding interface microstructure is composed of region I and region II. The region I consists of O, α2 and B2/β phase, and region II is made up of α2. Subsequently, the tensile tests indicate that the composite synthesized at 1050 °C for 2 h possesses a maximum strength of 812 MPa and a total elongation of 1.31% at room temperature, and a strength of 539.71 MPa and the highest total elongation of 10.34% at 750 °C. The well synergistic deformation ability between the interface and the two base alloys endows the composite an excellent tensile performance. Moreover, the composite processed at 1050 °C for 2 h behaves the best fracture toughness in both arrester orientation and divider orientation with the value of 32.6 MPa.m1/2 and 30.1 MPa.m1/2, respectively. The Ti2AlNb alloy in the laminated structure effectively release the stress around the crack tip and plays a role in toughening. Further, crack deflection, crack bridging, crack blunting and fragmentation also make contributions to enhance the fracture toughness of the laminated composites.

A β-Ti dendrite reinforced Zr-based bulk metallic glass composite (BMGC) was found to be brittle when cast in a large size. The reasons for the embrittlement and the effectiveness of the cryothermal cycling (CTC) treatment in restoring the mode I fracture toughness are examined. Plasticity in all the CTC treated BMGC is estimated from the distribution and occurrence of pop-ins in nanoindentation tests and by measuring the magnitude of enthalpy of relaxation (ΔHrel) via differential scanning calorimetry (DSC). This is further validated by examining the strain-to-failure (ef) in compression tests. Mode I fracture behaviour of the as-cast embrittled BMGC and the CTC treated BMGC, which exhibits maximum plasticity, is examined. Results show that both BMGCs are equally brittle and exhibit 5 times lower notch toughness (KQJ) than their tougher counterpart. Post-facto imaging of the side surfaces reveals the absence of notch-tip plasticity in both BMGCs. The lack of notch tip plasticity of CTC treated BMGC, despite exhibiting signatures of plasticity in nanoindentation and higher ΔHrel is rationalized by reassessing the origin of pop-ins in nanoindentation tests and describing the variations in chemical and topological short range ordering during CTC, respectively. Implications of these results in terms of improving the fracture toughness of structurally relaxed BMGCs via CTC are discussed.

BACKGROUND: Understanding the fracture mechanics of bone is very important in both the medical and bioengineering field. Bone is a hierarchical natural composite material of nanoscale collagen fibers and inorganic material. OBJECTIVE: This study investigates and presents the fracture toughness of bovine cortical bone by using elastic plastic fracture mechanics. METHODS: The J-integral was used as a parameter to calculate the energies utilized in both elastic deformation (Jel) and plastic deformation (Jpl) of the hipbone fracture. Twenty four different types of specimens, i.e. longitudinal compact tension (CT) specimens, transverse CT specimens, and also rectangular unnotched specimens for tension in longitudinal and transverse orientation, were cut from the bovine hip bone of the middle diaphysis. All CT specimens were prepared according to the American Society for Testing and Materials (ASTM) E1820 standard and were tested at room temperature. RESULTS: The results showed that the average total J-integral in transverse CT fracture specimens is 26% greater than that of longitudinal CT fracture specimens. For longitudinal-fractured and transverse-fractured cortical specimens, the energy used in the elastic deformation was found to be 2.8–3 times less than the energy used in the plastic deformation. CONCLUSION: The findings indicate that the overall fracture toughness measured using the J-integral is significantly higher than the toughness calculated by the stress intensity factor. Therefore, J-integral should be employ to compute the fracture toughness of cortical bone.

This work implements a first-principles calculations method to explore the effects of rare-earth element dopants on the properties of the α-Al2O3 (0001)/γ-Fe (111) interface. The results show that the work of adhesion (Wad) of the doped-x (x=Ce, Y, Sc, La, Er, Yb, Gb, and Nd) Fe/Al2O3 interface is obviously greater than that of the non-doped interface, especially the doped-Y interface with the maximum binding strength, is selected as the model of tensile test. In contrast to the non-doped Fe/Al2O3 interface, the critical strain and tensile stress of the doped-Y interface increased from 0.5% to 8% and 6.88–13.55 GPa, respectively, indicating the introduction of rare-earth Y changed the failure mode of the Fe/Al2O3 interface from brittle to toughness fracture, significantly improving the mechanical performance of the Fe/Al2O3 interface. Further, electronic structure revealed that electron at local location being exhausted early induced by stretching is the signal of the structural failure. Furthermore, it is also found that the doped-Y atom segregate towards the middle of the Fe/Al2O3 interface, resulting in the Y-(p, d) orbits hybridized with O-s orbit in the range from −23.58 to −19.83 eV and Y-(s, p and d) orbits hybridized with Fe-s orbit in the range from −7.52 to −3.51 eV. As a result, the segregation behavior of the doped-Y atom appears to act as an adhesive at the Fe/Al2O3 interface, and then the electron orbital hybridization effect produced among atoms is enhancement mechanism of interface.

Due to the poor compatibility between the reinforcement and Cu matrix, interfacial bonding is of vital importance for the comprehensive properties of graphene nanoplatelets (GNPs)/Cu matrix composites. Herein, we reported a novel hybrid reinforcement with pea-pod structure (surface protruding structure of GNPs) prepared via in situ synthesis, which contributed to the dramatically ameliorated interfacial structure of the composites and regulated the quasi-stability deformation process. The Cu@GNPs@Al2O3/Cu composite exhibited optimal strength (YS: 290MPa-0.45 vol% Al2O3, 300MPa-0.76 vol% Al2O3), moderate ductility (18%), as well as far exceeding the toughness of the GNPs/Cu composites. Concurrently, the electrical conductivity of the composite remains at a high level of 96.5 IACS%. The present findings may provide a feasible strategy to optimize interfacial structure by adjusting the structure of reinforcement, which enables improving comprehensive properties of Cu matrix.

Control of the formation and stability of reverted austenite is critical in achieving a favorable combination of strength, ductility, and toughness in high-strength steels. In this work, the effects of Cu precipitation on the austenite reversion and mechanical properties of maraging stainless steels were investigated by atom probe tomography, transmission electron microscopy, and mechanical tests. Our results indicate that Cu accelerates the austenite reversion kinetics in two manners: first, Cu, as an austenite stabilizer, increases the equilibrium austenite fraction and hence enhances the chemical driving force for the austenite formation, and second, Cu-rich nanoprecipitates promote the austenite reversion by serving as heterogeneous nucleation sites and providing Ni-enriched chemical conditions through interfacial segregation. In addition, the Cu precipitation hardening compensates the strength drop induced by the formation of soft reverted austenite. During tensile deformation, the metastable reverted austenite transforms to martensite, which substantially improves the ductility and toughness through a transformation-induced plasticity (TRIP) effect. The Cu-added maraging stainless steel exhibits a superior combination of a yield strength of ∼1.3 GPa, an elongation of ∼15%, and an impact toughness of ∼58 J.

The elucidation of fracture mechanisms is helpful for the optimization and design of toughness and microstructure of refractories. Fracture behavior of ultra-low cement bonded Al2O3–SiO2 castables was researched using the wedge splitting test coupled with digital image correlation technique (WST-DIC). Britleness of Al2O3–SiO2 castables is reduced by introducing andalusite aggregates into the castables. The characteristic length LCH, a parameter used to assess flexiblity of materials, was observed to reach 287.2 mm in andalusite-containing Al2O3–SiO2 castables, more than 5 times that of reference castables. Microcracks toughening is the main toughening mechanisms for flexibility improvement of the Al2O3–SiO2 castables containing andalusite. Microcrack network in microstructure of the Al2O3–SiO2 castables could be designed by exploiting the volume expansion caused by mullitization of andalusite and the the coefficient of thermal expansion (CTE) mismatch between the andalusite aggregate and the matrix. Unlike andalusite-free castables, castables containing andalusite possess a distinct fracture process zone (FPZ), the crack branching and deflection phenomena can be observed around the main crack during the fracture process, which leads to the prolong of the crack propagation path, the increase of the dissipation energy during the fracture, and the enhancement of resistance to crack propagation.

As main components of magnesia-based refractories, magnesia exhibits excellent properties such as high refractoriness and good basic slag corrosion resistance. However, magnesia produced from CaO containing cryptocrystalline magnesite has limited application owing to the low hydration resistance and poor thermal shock resistance (TSR). This work aimed to investigate the reinforcing effects of microscale monoclinic ZrO2 on free CaO containing magnesia for optimizing mechanical properties, TSR and hydration resistance. The results showed that adding ZrO2 could promote the removal of the open pores, strengthen the interface bonding between various grains and produce crack deflection, which improved flexural strength and fracture toughness. As a result, the TSR of the specimens was enhanced effectively due to increased strength and toughness and reduction in the thermal expansion coefficient. Besides, as the ZrO2 was introduced, hydration resistance of the specimens improved significantly, mainly attributing to the decrease in apparent porosity and elimination of the free CaO by forming CaZrO3 and cubic ZrO2 phases.

Fibre-reinforced engineered cementitious composites are increasing being used in construction due to their superior toughness and durability. For composite structural members additionally reinforced with steel bars, the bond–slip relationship between the composite and reinforcing bars is an important parameter for designers. To understand the bond behaviour between Chinese 500 MPa steel bars and composites, pull-out tests were conducted to study the influence of the bar diameter, cover thickness and embedded length on bond properties under tension. The results indicated that the process of the bond–slip failure for 500 MPa steel bars in composites can be divided into three stages: ascent, descent and remnant. The bond strength increased with a decrease in bar diameter, while shortening of the embedment length enhanced the bond strength. Specimens with a larger cover thickness achieved higher bond strength, but the enhancement in bond strength was negligible for specimens with a cover thickness greater than 55 mm. A formula for calculating the bond strength for Chinese 500 MPa reinforcing bars in composites was developed based on the experimental results and a consistent model for the bond stress–slip relationship was also obtained.

For dental materials, a certain defect tolerance would be beneficial. Some Ceria-stabilized zirconia (Ce-TZP) composites are promising dental repair materials, as they have been shown to exhibit an obvious amount of transformation-induced plasticity with almost no dispersion in strength data. The purpose of this study was to design a novel tricalcium silicate (C3S)-based dental repair material by adding 10 mol.% Ce-TZP to improve fracture toughness and dipotassium hydrogen phosphate (K2HPO4) as the setting accelerator. The study evaluated the physicochemical properties, in vitro cell activity, and antibacterial activity of Ce-TZP/C3S composite cement, and the results revealed that Ce-TZP/C3S cement showed a fast-setting ability and good washout resistance when the setting time was controlled within 26–43 min. With increasing Ce-TZP content, the mechanical properties, especially the flexural strength and fracture toughness, were gradually enhanced. Additionally, the 30% Ce-TZP/C3S composite showed good antibacterial activity and in vitro cytocompatibility. The study concluded that 30% Ce-TZP/C3S composites could be regarded as ideal candidates in the field of dental materials due to their excellent physical and chemical properties, antimicrobial activity, in vitro cytocompatibility, outstanding fracture toughness and fast-setting ability.

Vat photopolymerization is a versatile 3D printing method that produces parts using polymeric materials with uniform mechanical properties, high quality surface finish and high-resolution features. However, it is challenging to make composite materials with vat photopolymerization mainly due to the imperfect filler dispersion in the photo resin. Herein, we describe a methodology to incorporate aramid nanofibers (ANFs) into a 3D printable photoresin as a dispersion, followed by a solvent exchange process that limits anisotropic shrinkage and cracking of the printed polymer. By incorporating 0.60 wt.% of ANFs, both the tensile strength and toughness increased by 264 % and 219 % respectively, while the Young’s modulus had a 406 % increase compared to the control photoresin.

Using filler and impact modifiers for balancing stiffness and toughness properties is a common strategy for modification of polymer matrices’ performance. Nanocomposites based on poly lactic acid/polyolefin elastomer/including multiwalled carbon nanotubes/carbon black nanoparticles (PLA/POE/MWCNTs/CB) were produced using an internal mixer. Fuzzy rule- based system (FRBS) was applied to predict and simulate of mechanical properties of the samples. The fieldemission scanning electron microscopy (FESEM) was applied to determine the state of nanofillers distribution. The FESEM images showed that the carbon black and MWCNTs individually were well distributed. But, the simultaneous addition of nanofillers by more than 1 wt% from each one led to their agglomeration. The results illustrated that the presence of MWCNTs and carbon black separately and simultaneously led to an increase in tensile strength and Young’s modulus. The simultaneous presence of them led to an improvement in impact strength by 30%. Also, by incorporating POE into the PLA matrix, a significant increment in impact strength was obtained by 110%. The obtained surface plots from FRBS revealed that there is an interaction between nanofillers effects on the mechanical properties. Finally, a good agreement between the predicted mechanical properties using FRBS and evaluation tests led to extract accurate models with proper R2 and standard error for all responses.

The lamellar structure has an important impact on the mechanical properties of dissimilar laminated metal composites (LMCs), including the thickness ratio of dissimilar metal constituent layers and the number of layers. AA1100 and AA7075 with thickness ratios of 1:4 and 3:4 were fabricated for multilayer AA1100/AA7075 LMCs by hot accumulative roll bonding (ARB) technology. The bending fracture characteristics of AA1100/AA7075 LMCs with different thickness ratios and numbers of constituent layers were investigated. The research results indicated that AA1100/AA7075 LMCs with a low thickness ratio exhibited better bending ductility and toughness than those with a high thickness ratio, which was attributed to the crack growth resistance caused by the thickness of the soft AA1100 layer. The toughening mechanism introduced by crack deflection or arresting contributed to the enhancement in the toughness of the LMCs compared with that of the single 7075Al layer. The bonding interfaces of AA1100/AA7075 LMCs with different numbers of layers are continuous and straight due to the high ARB temperature. A decrease in bending toughness was observed as the number of layers increased. Unlike LMCs with a low number of layers, crack deflection or interface delamination is also considered a main toughening mechanism in dissimilar LMCs in addition to the thickness effect.

Leucite and zirconia are commonly used in the production of prosthetic dental materials. Leucite presents attractive optical properties but low toughness and wear resistance, which limits its use. Zirconia has much higher toughness, but due to aesthetic reasons and ageing issues, needs to be glass veneered. Chipping of such veneer is usually responsible for the abnormal wear induced on the antagonist teeth. Leucite reinforced with 25% of nano-zirconia is a promising alternative to overcome these issues, allowing the production of dental restorations without veneer. This study aims to investigate if leucite-zirconia composites have suitable optical, mechanical and tribological properties to be used in dental restoration. Samples with different compositions of leucite and/or nano-zirconia were produced by unidirectional compression and characterized concerning density, surface morphology, roughness, hardness, toughness, and translucency. Wear tests were performed in a chewing simulator using human cusps as counterbodies. Tests were also performed in glazed zirconia for comparison. 25% ZrO2 leads to the lowest wear of the tribological pair among the studied systems, except 100% ZrO2. This can be attributed to the toughening effect of zirconia and reduced size of third body particles. Abrasion was the main wear mechanism observed in this pair. In addition, this was the composite that presented the highest translucency.

To improve the toughness and friction properties of carbon fiber reinforced ceramic matrix composite, a Cu alloy modified carbon fiber reinforced TiC based ceramic matrix composite was designed and prepared by TiCu alloy melt infiltration at low temperatures up to 1100 °C. The as-produced composite was mainly composed of carbon, TiC, Ti3Cu4, TiCu4 and Cu phases. Due to the ductile Cu alloy introduced into the matrix, the composite showed good mechanical performance especially the fracture toughness. The flexural strength reached about 248.36 MPa while the fracture toughness was up to 15.78 MPa·m1/2. The high toughness of the composite was mainly attributed to the fiber bridging, fiber pull-out, interface debonding, crack propagation and deflection. The tribological performance of the as-produced composite was measured using SiC and 440C stainless steel balls as counterparts, respectively. The as-prepared composite exhibited good wear resistance and the wear mechanism was discussed based on the microstructural observations.

Extensive applications are found in aluminum matrix composites, where high strength to weight ratio, low weight and high corrosion resistance are needed. One of the categories of such materials is the SiC reinforced aluminum matrix composite. This reinforcing material belongs to ceramic group of materials and can withstand high temperature and improve several properties when incorporating in the grain structure of the base matrix. The introduction of SiC enhances wear resistance, hardness value and tensile strength. However, the use of high percentage of SiC material reduces the machinability (ductility) and toughness resistance and the machining of such material becomes difficult. In this current study, an attempt is made to develop an aluminum (LM25 alloy) matrix composite, which is reinforced with 7%SiC and 3%Gr particulates through stir casting route. The fabrication of composite is followed by evaluating the machining behavior of hybrid composite through electric discharge machining. During machining, current, voltage, pulse on time and pulse off time are selected as input controllable variables while material removal rate (MRR), tool wear rate (TWR) and over cut are chosen as responses. The experiments are carried out as per Taguchi's L9 OA, with the aid of ANOVA and significant parameters effecting responses are identified. Main effects plots are drawn and optimum set of input machining conditions are determined.

Metal/ceramic composites are in high demand in several industries because of their superior thermo-mechanical properties. Among various composite types, the interpenetrating phase composites (IPCs) with percolating metallic and ceramic phases offer manifold benefits, such as a good combination of strength, toughness, and stiffness, very good thermal properties, excellent wear resistance, as well as the flexibility of microstructure and processing route selection, etc. The fabrication of metal/ceramic IPCs typically involves two steps - i) processing of an open porous ceramic body, and ii) infiltration of metallic melt in the pores to fabricate the IPC. Although significant progress has been made in recent years for developing both porous ceramics and melt infiltration methods, to the best of the knowledge of the authors, no review article summarizing all the aspects of processing and properties of IPCs has been published till date. This review article is aimed at filling this gap. Starting with a brief introduction about the current status and applications of IPCs, the various processing routes for fabricating open porous ceramic preforms and melt infiltration techniques have been discussed. Subsequently, the data available for various important physical, mechanical, and thermal properties for IPCs have been critically analyzed to thoroughly understand their dependence on various structural and processing parameters. To compare the properties of IPCs with other relevant materials, seven different Ashby material property maps have been used, and the domains for IPCs have been created in them. For each map, the concept of material indices has been employed to critically discuss how IPCs perform in relation to other material classes for various optimum design conditions. Finally, a detailed future outlook for further research on IPCs has been provided.

In past one decade, polyamide (PA)6 feedstock filaments has proved its capabilities for fused deposition modeling (FDM) based functional prototypes requiring wear and impact resistance. The almond skin powder (ASP) is organic kitchen waste material, which has highest strength to weight ratio. Some researchers have developed PA6 based composite feedstock filament reinforced with ASP. But hitherto little has been reported on use of ASP reinforced PA6 based composite filament for 3D printing (using FDM) and its printing capabilities. In this research work an effort has been made to 3D print, 10% (by weight) ASP reinforced PA6 composite filament with open source FDM setup as a pilot study. The results are supported with mechanical testing, optical photo-micro graphical analysis. The functional prototype can be very useful in meta-material printing (requiring high modulus of toughness) and rapid tooling applications.

Conventional electrodeposition is used to develop Ni-Al2O3 nano-composite over the Al-2618 surface through nickel-plated immersion. Scratch investigation was carried out with respect to various process parameters such as immersion temperature, packing of particles and current density. The scratch resistance of electrodeposition composition was determined with the Ducom TR102-Scratch testing device and it was fortified with Rockwell C diamond stylus (0.2 mm rad.). Microscopic analysis was made of the morphology and scratch stages of the electrodeposited layer. The results indicates coating layer narrowly imitates the surface contour, as well as the toughness of a substance is influenced by its strength. Also the better adhesive strength could be achieve by higher temperatures, moderate particle loading and current density.

Stress Corrosion Cracking (SCC) and Hydrogen Embrittlement (HE) are two major degradation phenomena experienced by spring steel. The consequences of these phenomena have an impact both on the mechanic response, sufficiency, and life of the mechanical system. The susceptibility to premature failure is never the same and is unique for different environment combinations. There will be a combined effect of these phenomena. Here in this experimental investigation, an attempt is made to understand the tensile behavior of combined treatment. The pre-stressed specimens were corroded and post-treated with the HE process. Traditional tensile testing was used to investigate the combined effect of corrosion and post-treated HE. From the test results, it can interfere that the post hydrogen charged specimen exhibits ductility loss, but recover in the ultimate strength, and increase in yield strength. The dominance of recovery was also shown by an increase in fracture strength and toughness. The scanning electron microscope was used to assess the mechanism and to characterize it.

In the competitive industrial world, the composite materials have vast scope due to its mechanical and wear characteristics like strength, hardness, toughness, wear in micron and coefficient of friction. Conventional monolithic general materials have limitations concerning recently advanced materials like composite as well as Hybrid composite materials. The innovation of hybrid metal matrix composite has become an exciting task in material science and metallurgy. Aluminum alloy composites are primarily utilized in the car and the aerospace industry due to their excellent mechanical characteristics, including greater stiffness, low density, excellent corrosion resistance, and significant wear resistance. So in the present research, Wear and frictional characteristics of aluminum alloy-based hybrid composite material has been investigated with the help of tribometer testing apparatus. Tribological behavior of LM25 reinforced with Fly ash and Alumina with a varying percentage from 4%, 8%, 12% manufactured with stir casting technique and studied. The study was planned on Taguchi's approach, and the L9 array has been used for experimentation. In this research, experiments were conducted as per ASTM-G99 standard and with pin-on-disk (POD) tribo testing machine for characterization of Hybrid metal matrix composite. The speed of disc has the most significant impact, on the wear in micron after that the Normal loads and the reinforcement percentage. The reinforcement percentage shows more effect on coefficient of friction in hybrid composite material. The SEM images shows that abrasive wear of Hybrid composite material occur during Sliding wear of specimen on Pin-on-disc apparatus. The validation of results was done with the help of SEM (Scanning Electron Microscope) studies with the experimental results.

Composite materials are developed with the sole intention of augmenting the properties of metal/alloy through the addition of reinforcing materials. The composite of Al-6082 alloy with 5%, 10%, 15% and 20% percent by weight nano-SiC particulate reinforcement was successfully fabricated using the standard stir casting method. Using the rule of mixture, the physical properties such as the density, Poisson’s ratio, and the Young’s modulus were computed for the fabricated composites. The rule of mixture showed that the density and Young’s modulus was highest for composite with 20% nano-SiC reinforcement at 2.802 gms/cm3 and 136.2 MPa respectively. Whereas the Poisson’s ratio was maximum for composite with 5% nano-SiC reinforcement at 0.3225. For the strength evaluation, aappropriate specimens were prepared according to ASTM standards from the fabricated composites to test the hardness, tensile strength, compression strength, and impact strength. The hardness was tested using the Brinell’s hardness tester, which showed an increasing trend in the BHN, from 5% to 20%, at 84.34 to 93.39 N/mm2 respectively. The tensile tests showed an increasing tensile strength with a maximum measured at 327.94 MPa, for composite with 15% SiC. The tensile strength however reduced with further increase in nano-SiC reinforcement content at 20%. The compression tests showed a gradual increase in the compressive strength starting at 28.96 MPa for 5% nano-SiC reinforcement content, to 48.97 MPa for 20% nano-SiC reinforcement content. The impact tests conducted using the Charpy Test showed a gradual decrease in the impact strength starting at 6.2 Joules for 5% nano-SiC reinforcement content, to 4.8 Joules for 20% nano-SiC reinforcement content. This is due to the reducing toughness in the composites with a gradual increase in the nano-SiC reinforcement. The strength evaluation showed that for applications requiring maximum hardness and compression loads, the MMC of Al-6082 with 20% nano-SiC reinforcement would be best suited. It was also concluded that the applications with maximum tensile loading requirements, the MMC of Al-6082 with 15% nano-SiC reinforcement would be suitable. Furthermore, the impact strength evaluations has shown that the composite is highly unsuitable for applications with impact loading conditions.

The microscopic Bouligand-type architectures of fish scales demonstrate a notable efficiency in enhancing the damage tolerance of materials; nevertheless, it is challenging to reproduce in metals. Here bioinspired tungsten-copper composites with different Bouligand-type architectures mimicking fish scales were fabricated by infiltrating a copper melt into woven contextures of tungsten fibers. These composites exhibit a synergetic enhancement in both strength and ductility at room temperature along with an improved resistance to high-temperature oxidization. The strengths were interpreted by adapting the classical laminate theory to incorporate the characteristics of Bouligand-type architectures. In particular, under load the tungsten fibers can reorient adaptively within the copper matrix by their straightening, stretching, interfacial sliding with the matrix, and the cooperative kinking deformation of fiber grids, representing a successful implementation of the optimizing mechanisms of the Bouligand-type architectures to enhance strength and toughness. This study may serve to promote the development of new high-performance tungsten-copper composites for applications, e.g., as electrical contacts or heat sinks, and offer a viable approach for constructing bioinspired architectures in metallic materials.

Stainless steel (316) possesses higher strength to weight ratio, high toughness and high tensile strength. It has wide range of applications in fabrication of heat exchangers, boat fittings as wire rope clips, in making of tanks, springs and screws, Medical implants, Sinks and splash backs. Welding of these materials has always been a challenging task. Submerged arc welding due to its various properties and specification has been found suitable for this type of work. In this research work, weld bead geometry parameters; Dilution, Form Factor were optimized by using Response Surface Methodology (RSM). Welding current has been found to be the most crucial parameter among all the selected parameters.

In this paper, the evaluation of fracture toughness for hybrid fiber reinforced laminated composites was assessed for mixed mode fracture specimens of (CTS) compact tension shear. For investigational work, with and without flyash bi-directional composites specimens of 9 mm thick were prepared by hand layup process. Further different loading angles were considered stating from 0° and increased to 90° with an increment of 15°. Experimentation was carried out on peak load and loading angle for the determination of fracture toughness. The results revealed that the fracture toughness of without flyash specimens was 1.17 times lesser than with flyash specimens.

The present work is to optimize the geometric parameters such as width (W), breath, total width (C), height (h), and crack length (a) of glass fiber woven mat reinforced thermoplastic laminate composite for Mode-I fracture analysis with compact tension testing mode. The laminated HDPE composites were prepared by hot compression molding with three layers of HDPE and two-layer of glass fiber woven mat. The design of experiments (L27 Orthogonal array) was prepared based on the Taguchi technique with four parameters and three levels. The mode-I fracture toughness and energy-releasing rate were calculated for all samples. The ANOVA and regression equation were used to find the effect of toughness and energy releasing rate of the laminate composites. The experimental and regression results are compared and predicted the error. Finally, the optimum shape to laminate composites is suggested for predicting fracture behaviors of various synthetic and natural fiber woven mat reinforced polymer composites in mode-I under compact tension mode.

Rapid pressurization (RP) induced crystallization of polybutene-1 (PB-1) is performed at different temperatures of 90 °C, 125 °C and 180 °C under various pressures. The mechanical properties of RP PB-1 are investigated with a tensile device and in situ wide-angle X-ray diffraction (WAXD) is used to record the structural evolution during deformation. Using differential scanning calorimetry (DSC) and WAXD, it is found that RP in the melt state produces forms I/I′, while stable form I with a high melting point is generated by RP at 90 °C. All three RP PB-1 samples at 180 °C have lower melting temperature of form I crystals, and their fracture strain is nearly three times that of normal form I. P1T90 shows a small fracture strain equivalent to that of normal form I, because RP at 90 °C only accelerates the phase transition from form II to I. Form I′ that directly crystallized from the melt state and the thinner lamellae of form I contribute to excellent toughness, which are conducive to the molecular orientation along the stretching direction. The optimization of toughness caused by rapid pressurization provides a new idea for the regulation of the mechanical properties of PB-1.

Gap graded concrete, also known as pervious concrete, or enhanced concrete, is a storm water drainage replacement. Pervious or porous concrete is a homogeneous mixture of cement, fine aggregates to some percent, coarse aggregate and admixtures with partial substitutes of fine aggregate. The particle sizes and proportions of the materials used indicate the value and permeability of this form of concrete. We addressed the strength parameters and permeability of this concrete with various aggregate sizes in this paper. The 70:30 coarse aggregate mix ratio is used. Two coarse aggregate mixes of 20–10 mm and 10–6 mm were used in this study for the different aggregate ratios. The larger the aggregate, the better the porosity for rainwater runoff and storage. To achieve better performance, 15% fly ash is used as a substitute for cement in the mix design in the experiments. The water binder ratio is kept constant at 0.38, while the cement to aggregate ratio is set at 1:5. The porous concrete moulds are cast and tested for mechanical and toughness properties. For the above-mentioned tests, cubes, tubes, and beams are casted.

Inspired by the hierarchical structure of the pearl shell and its related multi-scale toughening mechanism, based on the combination of powder metallurgy technology and spark plasma sintering, a layered graphene and carbon nanotubes hybrid reinforced Cu matrix composite material was successfully prepared. Compared with other conventional Cu matrix composite materials, the compressive elongation of the bionic materials is significantly improved, and all of them are above 20%, which is attributed to the effective crack deflection and the pull-out of the reinforcing phase. In terms of overall strength and toughness, (0.8 wt% MWCNTs+0.2 wt% GNPs)/Cu has the best performance. Its tensile strength, compressive strength and compressive elongation are 103.63 MPa, 202.32 MPa and 33.49% respectively. The large grain size in the laminates is conducive to the movement of dislocations, while the interlayer interface and nanocrystalline grains hinder the movement of dislocations in the direction perpendicular to the laminates.

The following review paper thoroughly enables the readers to emulate the flexural behavior and impact test method for textile reinforced cementitious composites (TRCCs). The flexural parameters of ECCs corresponding to type of fiber material, fiber volume fraction, fiber volume length and strength parameters were discussed. For the textile reinforcement, the parameters like type of weaving pattern, mesh size, roving tex, fiber volume fraction and number of layers were discussed. Based on the tensile strength of textile fiber material, carbon, AR-glass, aramid and basalt fiber mesh were used for strengthening, repair works, plastering and reinforcement for thin elements. And also, the impact test performance on cementitious concrete composites is addressed as well as methods adopted for finding impact performance are discussed from the numerous literatures. This paper provides summary about the flexural and impact performance of textile fibers introduced into the concrete composites in different mesh sizes and fiber volume fractions. Generally, inclusion of textile fibers gives much more performance in tensile, toughness, flexural, energy absorption capacity and ductility in ECC composites. Many of the researchers have tried with different fiber materials for producing ECC and TRC composites separately, but only few of them used both have been discussed. Finally, from the literatures mostly artificial fibers are used for making textile reinforced composites.

In this work, the Al2O3-reinforced high Nb–TiAl laminated composite is successfully fabricated by an innovative way of direct-current magnetron sputtering combined with the foil-foil metallurgy, with assistance of vacuum hot-pressed sintering. Here, the Nb-coated aluminum foil and titanium foil, microstructure evolution, the lamellar plane distribution and the mechanical performances are carefully studied. Specifically, the composite is composed of the α2-Ti3Al, γ-TiAl and α-Al2O3 phase, in which the high Nb–TiAl matrix has a fully lamellar microstructure and a high content (∼6.5%) of Nb. Taken the textured titanium foil as raw material, the multi-stage annealing process is proved to be an effective way to control the lamellar plane distribution in the high Nb–TiAl matrix, showing that 82.3% of the lamellar planes forms an angle less than 30° from the RD-ND plane of the composite. Moreover, the bending strength and fracture toughness of the composite reach 817 MPa and 12.41 MPa m1/2, respectively. Further, the toughening and strengthening mechanisms are also detailly discussed. We believe that the major findings in this work can provide a new idea to design the high strength-toughness intermetallic-ceramic composites.

The cryogenic fluid storage and transfer have been an area of interest for space applications. Efficient and safe storage of cryogenic fuels like liquid oxygen and liquid hydrogen is very critical. This study focused on the suitability of (3- Aminopropyl)trimethoxysilane as toughening agents for epoxy resin-based systems for cryogenic applications. We focused on diglycidyl ether of bisphenol A (DGEBA) with triethylenetetramine (TETA) as a curing agent at cryogenic temperatures. (3-Aminopropyl) trimethoxysilane was mixed in Epoxy with the help of a magnetic stirrer and ultrasonicator. CFRP panels made of plain weave carbon fiber and silane modified epoxy were fabricated using Vacuum Assisted Resin Transfer Molding (VARTM) technique. Samples were cut out as per ASTM standards, and Izod Impact test was conducted at room and cryogenic conditions. The toughness was witnessed to be improved at both room as well as cryogenic conditions. Silane successfully reduced the indigenous cross linking density of epoxy, which is making it brittle and stronger at the same time. Silane reduces the indigenous cross linking density of epoxy at cryogenic temperatures, which increases its toughness but at the cost of its overall strength. Also the mechanism of fracture and energy dissipation was studied and summarised using macroscopic fracture analysis and FTIR analysis.

The fiber acquired from the dry external covering of the coconut fiber named as “coir” has the best sturdiness among all naturally available fibers. These coir strands tend to be utilized as a support in minimal expense substantial designs especially in seismic tremor districts due to their property of durability and toughness. The present study is a laboratory investigation on determining the robustness of Coconut Fiber Reinforced Concrete (CFRC) and its behavior under high temperatures. Adopting the mix design of M20, various specimens were prepared by inclusion of coconut fibers and cured. Set of cube and cylindrical specimens were subjected to temperature 200⁰C separately and compared with control specimens to determine variation in strength. A study comparing the strength aspects of CFRC, and conventional concrete subjected to normal room and high temperatures at various ages of concrete is made.

MoAlB has been regarded as a promising high-temperature structural ceramic, but the strength and toughness are still insufficient in the practical application. In this work, MoAlB ceramic bulk with superior hardness, strength and toughness has been fabricated by adding 0.15 mol. % Si. The MoAlB-0.15Si bulk is composed of Si-doped MoAlB, Mo(Al, Si)2 and ultrafine Al2O3. The Vickers hardness ranges from 14.2 to 12.5 GPa with the tested load increasing from 10 to 200 N. The Vickers indentation remains the intact tetragonum in spite of the appearance of corner cracks, indicating the excellent damage tolerance. The flexural strength, fracture toughness and compressive strength of MoAlB-0.15Si are 518.46 MPa, 7.01 MPa m1/2 and 2.62 GPa, respectively, obviously superior to the present MoAlB polycrystalline bulk. Si doping, grain refinement, strengthening effect of ultrafine Al2O3 and phase transformation from Al8Mo3 to Mo(Al, Si)2 jointly account for the improvement of comprehensive properties of MoAlB bulk.

In recent years, plastic wastes represents one of the main threats to the environment. However, the use plastic fibers in concrete could be a sustainable solution to the problem of plastic waste accumulation. Moreover, the use of fibers in the production of concrete is one attempt to remedy this brittleness and to enhance other properties such as toughness and ductility. In this study, polyethylene terephthalate (PET) fibers produced from waste plastic bottles was used in reinforced concrete RC beams. PET fibers were included in concrete at two percentages (0.5% and 1% by volume). The influence of layered distributions of PET fibers in concrete on the flexural behavior of beams was also evaluated. For each mix, three layered PET fibers RC beams were prepared. Comparison with beam containing the same PET fiber percentage (full section) was presented as well. The flexural test parameters included the determination of first cracking, the yield, and the ultimate load, in addition to the deflections related to these loads. Furthermore, failure modes, toughness, and ductility were also evaluated. The use of PET fiber concrete with a layered distribution enhanced the ultimate load considerably. Moreover, the load–deflection relationships illustrated a tendency of layered PET fibers concrete beams to exhibit further deflections before failure. The toughness capacity approximately doubled for beams reinforced with 1% PET fibers concrete in the bottom quarter, bottom half, and top half sections of layered RC beams. This impressive enhancement of the flexural toughness and ductility using the layered distribution is a promising finding that could promote this type of sustainable concrete in various structural applications.

In this era, composite materials made of natural fibers are gaining the attention and interest of researchers, scientists, and engineers due to their impeccable features in contrast to synthetic fibers. Composite materials can be easily modeled and produced in various dissimilar forms as per the need. In this study, four different composite samples were prepared using three distinct fibers; two natural-banana (B) and sisal (S) and one synthetic-glass (G), by varying the weight percentage of banana and sisal. For each sample, the stacking sequence of the fibers are (B-G-S-B), (S-B-G-S), (G-B-B-S), and (B-S-S-G), oriented at (900,+450,−450,900) and put through a uniform point load. So, a total of sixteen composite samples were evaluated for directional deformations, stresses, and rotations using ANSYS Mechanical APDL 15.0. The outcome obtained showed that the arrangement of fibers in the sequence sisal-banana-glass-sisal (S-B-G-S) at different orientations is superior in terms of toughness and distortion resistance in contrast to all the sixteen arrangements.

In spite of considerable improvements in the manufacturing of body armor using lightweight and high-strength fibres, demands for lighter and more flexible products capable of providing sufficient protection against various types of threats has not waned. Among high strength fibres, ultra high molecular weight polyethylene (UHMWPE) possesses superior mechanical and physical properties. Nevertheless, the use of UHMWPE fabric with a shear thickening fluid (STF) materials for the manufacture advanced liquid body armors has been unsuccessful as this polymer is inherently inert and cannot bond or readily interact with other materials. To address these challenges, this research thesis focused on the development of a new method to increase the performance of UHMWPE fibre/fabric for high impact applications and improve its capability to bond with silica-based STF materials. A novel coating technique was developed using a nylon solution with UHMWPE fibre which results in a strong interlocking mechanism and the creation of a uniform coating without adding extra thickness to the fibre. Standard penetration tests showed considerable improvement in puncture/stab resistance of a nylon coated UHMWPE fabric compared with the uncoated fabric (with equivalent areal density) in terms of energy absorption, which was also explained by the scanning electron microscope (SEM) images of ruptured areas. In order to further improve the penetration resistance of UHMWPE fabric, a dispersion of fumed silica particles in polyethylene glycol (PEG) was synthesized exclusively via a novel sequential ultrasonication technique to incorporate with a multilayer stack of UHMWPE fabric. A complete set of rheological measurements, zeta potential and SEM analysis were done to study the viscoelastic characteristics and tune the stability of the synthesized STF samples. Evidence of the improved adhesion of STF materials to UHMWPE fibres coated with nylon from the SEM images was observed. Finally, while the evidence of improved mechanical properties of nylon coated UHMWPE were provided (e.g. higher creep resistance and toughness), its potential application for the manufacturing of medical devices was also explored. As a result, from the preliminary cytotoxicity and osteolysis assessments, it was shown that the biological compatibility of UHMWPE was improved when it was coated with nylon.

Relevance. The load on a reinforced concrete slab with high strength lightweight aggregate concrete leads to increased brittleness and contributes to large deflection or flexure of slabs. The addition of fibers to the concrete mix can improve its mechanical properties including flexure, deformation, toughness, ductility, and cracks. The aims of this work are to investigate the flexure and ductility of lightweight expanded clay concrete slabs reinforced with basalt fiber polymers, and to check the effects of basalt fiber mesh on the ductility and flexure. Methods. The ductility and flexural/deflection tests were done on nine engineered cementitious composite (expanded clay concrete) slabs with dimensions length 1500 mm, width 500 mm, thickness 65 mm. These nine slabs are divided in three reinforcement methods types: three lightweight expanded clay concrete slab reinforced with basalt rebars 10 mm (first slab type); three lightweight expanded clay concrete slab reinforced with basalt rebars 10 mm plus dispersed chopped basalt fiber plus basalt fiber polymer (mesh) of cells 2525 mm (second slab type); three lightweight expanded clay concrete slab reinforced with basalt rebars 10 mm plus dispersed basalt fiber of length 20 mm, diameter 15 m (third slab type). The results obtained showed physical deflection of the three types of slab with cracks. The maximum flexural load for first slab type is 16.2 KN with 8,075 mm deflection, second slab type is 24.7 KN with 17,26 mm deflection and third slab type 3 is 32 KN with 15,29 mm deflection. The ductility of the concrete slab improved with the addition of dispersed chopped basalt fiber and basalt mesh.

The purpose of this study was to optimize the conditions of the gas–metal arc welding using CO2 shield gas (CO2 arc welding) with hot-wire feeding technology. A high-speed camera was used to investigate welding phenomena of a butt joint of 36-mm-thick steel plates. The optimum parameters were determined under combinations of the welding current (300 or 400 A) and hot-wire feeding speed (0 to 12.5 m/min) to avoid molten metal precedence. A sound joint was achieved with only four weld passes using optimum conditions. Adequate joint properties, including tensile strength and toughness, were obtained. The optimum conditions provided a welding process with both high efficiency and low heat input.

Here, in order to develop the metallic materials with excellent relationship between strength and toughness for application, the FeCoCrNi + FeCoCrNiAl-laminated high-entropy alloys (HEAs) had been fabricated by laser melting deposition (LMD) additive manufacturing technique. The process parameter databases for FeCoCrNi and FeCoCrNiAl HEAs were built by orthogonal experiments and statistics method, which helped to select the optimised process parameters for the two HEAs. Then, the differences in the forming process, phase structure, and grain morphology of FeCoCrNi and FeCoCrNiAl HEAs were systematically investigated during the fabrication of the FeCoCrNi + FeCoCrNiAl-laminated HEAs. The results show that variations in surface tension, wettability, and other physical properties between the two HEAs led to significant differences in their LMD processes. Al not only influenced the fabrication process of both HEAs, but also promoted the phase transition from FCC (FeCoCrNi) to BCC (FeCoCrNiAl). In addition, Al also acted as a strong limiting factor to inhibit the effect of supercooling on the grain morphology, which transformed from coarse columnar grains to fine equiaxed grains. The columnar grains, with a preferred orientation in the FeCoCrNi-deposited wall, promoted the suppression of the inhibitive effects of the phase structure and strong limiting factor, led to the growth of the columnar grains in the FeCoCrNiAl-deposited wall, and helped achieve long-distance continuous growth of columnar grains across the interface in the subsequently deposited wall. The methodology used in this study could be meaningful for the exploration of process parameters of LMD, and the discoveries of grain characteristic help to understand the microstructure transition in laminated heterogeneous HEAs fabricated by laser additive manufacturing.

The mechanical properties and phase transformation behavior of carbon nanotube (CNT) reinforced 3 mol% yttria-stabilized zirconia (3YSZ) composites prepared by spark plasma sintering are reported for CNT contents between 0 and 7 wt%. CNTs are shown to improve the fracture toughness of the material by a combination of fiber pull-out and crack-bridging toughening mechanisms. Stress release by these mechanisms results in a smaller proportion of the YSZ matrix transforming from the tetragonal to monoclinic phase, reducing the microcracking that would otherwise result from cumulative volume expansion associated with this well-known phase transformation process. This produces a material with high fracture toughness without compromising hardness, thereby providing superior mechanical reliability. The high fracture toughness (7.0 MPa∗m1/2) of the 7 wt% CNT/3YSZ composite makes it an attractive material for high-impact, high-temperature applications such as environmental barrier coatings.

Bio composites as nacre show outstanding mechanical properties which surpasses those of their single constituents. This is due to their complex structure, in which the small building blocks of the hard component are embedded in a softer matrix, thus combining strength and toughness. This combination makes such materials interesting for various applications, e.g. for tooth replacement materials but also for industrial structural materials. Therefore, the interest is to develop scalable processes for the production of artificial composites. In this work a Nano Spray Dryer is used to produce polymer-encapsulated magnetite particles from a magnetite-polymer-suspension. A Design of Experiment study is conducted which identified the suspension composition as the major influencing factor on the product properties. The particles are then warm-compacted and the composite pellets are examined for their mechanical properties and structure. With this method composites with bending strength of 91.2 MPa and Young's modulus of 9.2 GPa were produced.

This study is aimed at addressing the experimental and theoretical investigation of the compressive behavior of steel reinforced concrete (SRC) composite columns containing steel fibers considering the stirrups’ confinement effects. Variables used to fabricate and evaluate the performance of the steel reinforced fibrous concrete (SRFC) columns include the steel profile shape (both H -shaped and C -shaped), volume fraction of steel fibers ( 0 , 0.75 , and 1.25 % ), and spacing of stirrups ( 40 , 65 , and 130 m m ). In total, 36 short column specimens were fabricated and such parameters as the axial bearing capacity, compressive stress–strain curves, ductility, peak strain and toughness were investigated through the axial compression test. According to the results, the axial bearing capacity of concrete-confined steel columns was affected by the steel shape inside; the axial bearing capacity of H -shaped cross-section columns was more - due to their more confinement - than that of C -shaped ones. Although adding, and increasing the percentage of, steel fibers increased the columns’ axial bearing capacity slightly (up to 6 % ), their ductility and energy absorption improved significantly. Increasing the spacing of stirrups from 40 to 130 m m not only resulted in a 12 % reduction in the axial bearing capacity, but also reduced the contribution of the composite action of both H - and C -shaped profiles by more than 70 % . Finally, as predicting the SRC column strength is important, relationships presented by ACIITG , A S 3600 , C S A - A 23 , E N 1994 , J G J 138 , and N Z S 3101 for the prediction of the axial bearing capacity were thoroughly studied and showed that all had ignored the confinement effects. Considering the latter, this study modified the relationships, corrected the predicted results and compared them with both the experimental results of this study as well as those of other researchers’ which showed a good correlation between the results.

Diglycidyl ether of bisphenol A (DGEBA) is a kind of widely used epoxy resin, but its thermosets normally show high brittleness and poor impact resistance due to the intrinsic rigid aromatic rings, which limit its application greatly. To avoid this drawback, we proposed a method to prepare a series of hyperbranched epoxies (HBEPs) with different molecular weights. After HBEPs were cured with methyl tetrahydrophthalic anhydride (MTHPA), characterizations were carried out to evaluate the properties of the cured HBEP samples. Testing results indicate that the hyperbranched thermosets can achieve excellent mechanical strength and toughness (tensile strength: 89.2 MPa, bending strength: 129.6 MPa, elongation at break: 6.1%, toughness: 4.5 MJ m–3, and impact strength: 6.7 kJ m–2), which are superior to those of the thermosets of commercial DGEBA (tensile strength: 81.2 MPa, bending strength: 108.2 MPa, elongation at break: 3.0%, toughness: 1.5 MJ m–3, and impact strength: 4.2 kJ m–2). In addition, HBEP with the highest molecular weight and degree of branching shows the best comprehensive mechanical properties. All hyperbranched thermosets exhibit high glass-transition temperatures (Tg) and thermostability, which further illustrates the potential application value of HBEPs.

Soilcrete properties modified with two types of polymer up to 0.20 % (% wt. dry weight of cement) were tested and quantified. The stress–strain curve of modified soilcrete with polymers was examined for curing periods up to 28 days and modeled using two different mathematical models. The flowability of the soilcerte was maintained within the range of 105 to 110% as recommended by ASTM standard. Polymers decreased the water/cement ratio ( w / c ) by 14.5 to 25.5%, based on the type and amount of polymers. The compressive strength and modulus of elasticity of soilcrete increased by 72% to 153% and by 55% to 195%, respectively, when the soilcrete was modified with 0.20% of polymers. The nonlinear Vipulanandan p-q equation was employed to predict the stress–strain behavior of the modified soilcrete with polymers and was compared with the β model prediction. Based on the statistical evaluation tools, the Vipulanandan p-q model predicted the stress–strain relationships better than β model. Linear (LM) and nonlinear relationships (NLM) were also used to predict the compressive strength, modulus of elasticity, and toughness of the soilcrete as a function of w/c, curing time, and polymer contents.