High Strength Ratio Research Articles

Effects of cryogenic treatment on mechanical properties and crystal orientation of 0.25C-0.80Si-1.6Mn steel with extraordinary strength-toughness

Deep cryogenic treatment (DCT) in the phase transition region of austenite (A) to ferrite (F) is a novel process that can efficiently improve the content of martensite (M) and F of dual phase (DP) steel. In this work, microstructure transformation in DP structural steel treated by DCT was investigated in detail. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) were used to characterize the microstructure, alloy distribution, grain size, and orientation for the DP structural steel. The results demonstrated that DCT could effectively improve the yield ratio and mechanical properties of the tested steel. F and its large-angle significantly reduced the influence of fine-grain strengthening on the reduction of yield ratio. This research offered innovative technical support and theory guidelines for producing and studying such extraordinary strength-toughness DP steel with high strength and low yield ratio.

Hole Introduction Effect on The E-Glass WR 185 Fibre Reinforcement Polyester

Challenge to use a light structural material for aero vehicle could be answered by fibre reinforced polymer composite. This composite has high ratio of strength to weight. In application this composite should be in mechanical assembling such as bolt. So that, investigation of hole introduction on the composite integrity and behaviours are needed. In this study, E-glass WR 185 fibres used as reinforcement in polyester BQIN EX 157 matrix. The composite made by hand lay-up methods; in which 13 layers of E-glass fibres were laminated one by one layer with polyester resin. After dried up, composite was cut off to made specimen for density, tensile and compression test. Some of tensile and compression specimens were drilled (marked as “open hole specimen”) in their centre. The result showed density of 1.12 g/cm3, maximum strength of 178 MPa (tensile) and 130 MPa (compressive). Introducing an open hole reduced strength to 119 MPa (tensile, decreased ∼33%), and to 112 MPa (compressive, ∼14%). Reducing strength is well confirmed with change of failure type; from lateral at grip top (LAT) to lateral gage middle (LGM). LGM of the open hole specimen means crack starting from the hole to both of lateral direction.

TEMPO-oxidized cellulose nanofibers/polyacrylamide hybrid hydrogel with intrinsic self-recovery and shape memory properties

Shape memory hydrogels attract increasing attention due to their promising applications as intelligent biomaterials for actuators, biomedicine and sensory applications. Nonetheless, the integration of synergistic characteristics providing good mechanical properties and ideal self-recovery rate still remains a challenge. To tackle this, we develop a novel nanocomposite hydrogel by radical polymerization. TEMPO-oxidized cellulose nanofibers (TOCNs) with high strength and ultra-high aspect ratio were introduced to improve the energy dissipation mechanism and enhance the fatigue resistance of polyacrylamide (PAAM) hydrogel. Interestingly, the nanocomposite hydrogel displays unprecedented shape memory properties through coordination with Fe3+. The resulting TOCN/PAAM hydrogel achieves excellent energy dissipation capability (9.68 MJ m−3 at 60% strain), satisfactory viscoelasticity (51.1 kPa) and good self-recovery rate (about 93.2% after 30 min recovery). In particular, the 3% TOCN/PAAM-Fe3+ hydrogel exhibits better tensile performance. This nanocomposite hydrogel with good shape memory properties and excellent mechanical strength has broad application prospects in soft actuators and sensory research.

Fabrication, micro structural and mechanical characterization of Zircon Particles (ZrSiO4) reinforced Aluminum alloy (MMCs)

This paper presents the review on fabrication, Microstructural analysis, and Mechanical Characterization of Zircon silicate Particles (ZrSiO4 ) / Aluminum Alloy composite using the stir casting method. Aluminum alloy is known for its low density, high ratio of strength and weight, improved mechanical property, and corrosion resistance. Particulate reinforcement is widely preferred because of its isotropic properties which ease the homogenous distribution with the aluminum and its alloy. Zirconparticles (ZrSiO4) are the combination of ZrO2 , SiO2 , Fe3O2 , TiO2 , and Al2O3 . This review encapsulates the recent research work on different fabrication techniques, different characterizations, Microstructural analysis, and Fractroscopic studies on different Aluminum alloy matrix and ceramic materials reinforcement combination composites which improve physical, Corrosion resistant, microstructural, and mechanical properties.

A bifunctional hexa-filamentous microfibril multimetallic foam: an unconventional high-performance electrode for total water splitting under industrial operation conditions

Cellulose in various forms possesses high strength, low density, and high aspect ratio with a three-dimensional open network structure, making them ideal candidates as current collectors in energy conversion application.

A method using beam search to design the lay-ups of composite laminates with many plies

Due to high specific strength and stiffness ratios, composite materials are widely used in industries where minimising structural mass is of paramount importance, such as the aerospace sector. However, designing lightweight composite laminates is challenging due to the large number of discrete design variables involved, e.g. ply numbers and fibre orientations which are usually restricted to a set of predefined values. The number of possible laminate solutions grows exponentially with increasing ply count, quickly rendering complete enumeration impossible. Current mixed-integer programming techniques for designing composite laminates with many plies either exhibit insufficient design space exploration, or demand inconceivable computational effort. As a result, laminates often have sub-optimal properties, e.g. excessive weight. We propose a novel deterministic optimiser for finding the lay-up of composite laminates with many plies. Lay-ups must match desired stiffness properties called Lamination Parameters (LPs). The design-space is explored by a procedure that uses beam search to promote fast convergence towards optimal or near-optimal solutions. Additionally, the optimality of the design solutions is improved by local searches which are performed after a first guess of the stacking sequences. The proposed optimiser is shown to retrieve symmetric laminate lay-ups with as many as 300 plies within a few minutes.

The Construction of Conforming-to-shape Truss Lattice Structures via 3D Sphere Packing

Truss lattices are common in a wide variety of engineering applications, due to their high ratio of strength versus relative density. They are used both as the interior support for other structures, and as structures on their own. Using 3D sphere packing, we propose a set of methods for generating truss lattices that fill the interior of B-rep models, polygonal or (trimmed) NURBS based, of arbitrary shape. Once the packing of the spheres has been established, beams between the centers of adjacent spheres are constructed, as spline based B-rep geometry. We also demonstrate additional capabilities of our methods, including connecting the truss lattice to (a shell of) the B-rep model, as well as constructing a tensor-product trivariate volumetric representation of the truss lattice — an important step towards direct compatibility for analysis.

Production and characterization of bamboo and sisal fiber reinforced hybrid composite for interior automotive body application

Composite materials have high strength to weight ratio with low density and high stiffness to weight, high strength ratios, and high fatigue strength to weight ratio compared to traditional engineering materials making them find wide applications in structural constructions. When the lightweight composite materials which are made of lightweight natural fibres are used in automotive application, the fuel economy of the vehicle improves reducing the related harmful emissions. The aim of this research is to develop and characterize the performance of sisal and bamboo reinforced polyester hybrid composite (BSFRHC) with different fibre orientation of sisal and unidirectional (UD) bamboo fibre. Next, BSFRHC was fabricated with 20% total fibre volume fraction. Of this total fibre volume, the composite is fabricated in 3:1 bamboo to sisal fibre ratio using hand lay-up technique. Then tensile, compressive, impact and flexural tests were carried out. In general, it is concluded that as varying fiber orientation, the tensile strength varies. The higher tensile strength is observed with 0° fibre orientation of bamboo/sisal fiber reinforced hybrid composite. From compressive strength of the hybrid composite reinforced with bamboo/sisal fibre, it is observed that the 0°-fibre orientation composite is exhibiting higher compressive strength than 90° fibre orientation composite and bidirectional (0°/90°) fibre orientation composite. Unidirectional 90° fibre orientation was found to have a higher tensile and flexural strength whereas unidirectional 90° and bidirectional (0°/90°) fibre orientation nearly have the same value of tensile strength, whereas bidirectional (0°/90°) was found to be having higher flexural strength than unidirectional 90° fibre orientation. Impact analysis of vehicle internal door panel made of BSFRHC was done using ANSYS Software. Furthermore, it is found that the bamboo and sisal fibre reinforced hybrid composite in unidirectional 0° has the potential to be used for automotive interior part application.

Optimal design of cold roll formed steel channel sections under bending considering both geometry and cold work effects

Optimal design of a structural member is a design process of selecting alternative forms to obtain its maximum strength while maintaining the same weight, leading to the most economical and efficient structure. Amongst steel structures, cold rolled steel ones can effectively gain this requirement as they are thin-walled structures that offer the high ratio of strength over weight. However, the design is very challenging as these members are prone to buckling and failure at low loads. In this paper, the buckling and ultimate strength of cold rolled channel sections was studied using numerical modelling. In order to improve the section strength, the development of various alternative cold rolled formed sections included additional bends such as intermediate stiffeners. The section strength was optimised through a practical approach which altered the stiffener's position and shape and searched for maximum buckling and ultimate strength under bending. In this approach, a nonlinear Finite Element model was first developed for an industrial channel beam subjected to four-point bending tests and this model was validated against experimental test data. The verified model was then used to conduct a parametric study in which the effects of a stiffener's properties on the section strength including its position, shape, size and material properties by the cold work at bends were investigated in detail. Several different cold rolled channel sections having intermediate stiffeners at web and flanges with and without the cold work effect on material properties at the stiffener's bends were considered for this investigation. In addition, a design method, the Direct Strength Method (DSM), was utilised to take into account the effects of a stiffener's properties on the section strength and results were compared with the Finite Element modelling results. It was found that some significant improvements were obtained for the section strength of the optimised sections in comparison to the original sections. An optimal shape for the channel section with maximum ultimate strength in distortional buckling could be obtained with both the stiffeners' position, shape, size and quantity, and the cold work effect. The cold work effect was found most significant in the cases of changing the width of the web stiffeners and the position of the flange stiffeners. It also revealed that, the currently available DSM beam design curve for distortional buckling provided good agreement in predicting buckling load and ultimate strength capacity for most of the considered sections with and without the cold work effect included; however, the DSM provided overestimate results compared to the Finite Element model results in the sections with web intermediate stiffeners, in particular, when the tip of web intermediate stiffener moved away from the web-flange junction in the horizontal direction.

A grain-based model considering pre-existing cracks for modelling mechanical properties of crystalline rock

Mechanical properties of crystalline rock are greatly affected by its micro-structures which are characterized as highly-interlocked polygon grains and presence of micro-defects. Due to insufficient consideration of micro-structures in crystalline rock, previous simulations using discrete element method (DEM) cannot realistically reproduce the mechanical properties of crystalline rock including crack closure behaviour and high ratio of uniaxial compressive strength (UCS) against tensile strength (TS). The irregular shape of minerals in crystalline rock is modelled by discrete element method (DEM) using grain-based model (GBM). Presence of initial cracks is incorporated into GBM by introducing two notional contact surfaces to model gradual closure behaviour under compressive loading, and to obtain a higher UCS/TS ratio. The stress-strain response and crack evolution including crack closure, crack initiation, crack coalescence as well as development of macroscopic shear failure can be realistically reproduced with the proposed model. A calibration procedure is proposed to match properties of Remiremont granite under room temperature. The influence of initial cracks on the rock is then comprehensively studied. The simulation results show a good agreement with the experimental outputs under various treatment temperatures. By modelling the polygon grain and pre-existing cracks, the simulated UCS/TS ratio can be more realistic and increased up to a value of 49.

Enhanced Corrosion Performance By Micro Arc Oxidation Coating with the Addition of 2-Aminobenzimidazole Loaded Halloysite Nanotubes on AZ31 Alloy

The application of Magnesium alloys has drawn great attention in recent years. As the lightest structure metal on earth, the usage of Mg is attractive to the automotive, aerospace and electronics industries owing to its high weight-to strength ratio. Unfortunately, the poor corrosion resistance impedes the development of Mg alloys. To date, several methods have been proposed to improve the anti-corrosion ability, such as conventional anodizing, sol-gel coating, and micro arc oxidation (MAO). MAO is an innovative technique for generating surface oxide coatings on valve metals and alloys, which exhibits strong adhesion to the substrate, high thickness, hardness, corrosion and wear resistance, and provides an environmentally-friendly alternative to acid-based anodizing treatment. Despite all these advantages, the intrinsic structural imperfection of MAO coatings, including a loose structure featured by micro-pores and micro-cracks, facilitate quicker penetration of the corrosive ions into the base magnesium, and thus, increase the rate of corrosion. To overcome the problem of porous MAO film, composite coatings with self-healing ability that are capable to repair themselves when damage occurs have been utilized. In this study, the concept of self-healing is carried out by incorporating corrosion inhibitors, 2-aminobenzimidazole (2-ABI), loaded nanocontainers, halloysite nanotubes (HNT), to silicate-based electrolyte to obtain MAO coatings on AZ31 alloy in single step. The coatings are evaluated by SEM, EDX, and XRD. Corrosion performance is studied with EIS, PDP and salt spray test. The effects of various electrical parameters, including current density, frequency and working time, on the coating are also investigated. Experimental results indicate that the corrosion resistance of MAO films with the addition of 2-ABI loaded HNT is significantly improved, and thus confirms the feasibility of 2-ABI as corrosion inhibitor to Mg alloys.

Experimental Study of Cement Alkali-Resistant Glass Fiber (C-ARGF) Grouting Material.

Mixing alkali-resistant glass fiber (ARGF) into grouting slurry can prevent the development of cracks; thus, understanding the properties of ARGF grouting material is important for applications in engineering. Two types of ARGFs (Cem-FIL®60 and Anti-Crak®HD) were selected as mixing materials, and their performance was tested in four areas, namely, compressive strength, tensile strength, flexural strength, and impervious performance, under four different mixing amounts of fiber (0%, 0.25%, 0.5%, and 1.0%). Results demonstrate that the addition of ARGF increased the compressive strength and tensile strength of the grouting slurry, and the best performance was at 0.5%. The effect on the flexural strength and impervious performance was related to the mixing amount, and the fiber may have induced a counter-effect for certain amounts of added ARGF. Mixing ARGF could increase the early strength ratio of grout; however, a high early strength ratio did not necessarily result in high strength, as the flexural strength did not change synchronously with the early strength ratio; a similar pattern was found for the impermeability. Cem-FIL®60 had a better effect on the properties of grouting materials than Anti-Crak®HD. These results were successfully applied in the water-plugging and reinforcement engineering of a karst tunnel.

A comparison LCA of the common steel rebars and FRP

The use of fiberglass-reinforced polymer (GFRP) as an alternative solution in strengthened concrete technology significantly has been increased recently. Fiberglass rebar (GFRP) took a stronger position in modern construction. This is due, on the one hand, to its high specific strength (ratio of strength to specific gravity) and on the other hand, too high corrosion resistance, frost resistance, and low thermal conductivity. Its non-corrosive nature has turned the attention of many researchers to make several studies on the different types of GFRP products. Insufficient resources for metal increase the requirement for renewable resources such as composites. However it is considered the environmental issues as a most significant problems which needs to study in every case, from this point of view despite all the GFRP advantages the environmental impacts of this material takes an important place to study, in this study the production stage of GFRP has been studied, in addition to better understand of the issue a comparison between steel rebars and GFRP was conducted, a significant environmental impact was seen in GFRP production process which needs to be considered for production of these materials.

Investigation of surface roughness and chip morphology of aluminum alloy in dry and minimum quantity lubrication machining

Aluminum alloys are used in different sectors due to their lightness, high strength ratio, corrosion resistance, and heat conduction, and electrical conduction, non-magnetic and non-toxic properties. Despite these properties, determination of surface quality is a critical factor for improving the functional properties of aluminum alloys such as high fatigue strength, corrosion behavior, and wear resistance. In this study, the effect of high-speed machining of Al7075-T6 aluminum alloy on the surface quality of Al7075-T6 alloy was investigated. Besides, the effect of different conditions on-chip formation was studied. The experiments were carried out in three different cutting parameters in dry and minimum quantity lubrication (MQL) conditions. It was found the surface quality of the Al7075-T6 alloy workpiece was improved when the test results performed in the MQL condition were compared to the dry condition. When the chip structure is examined, longer chip formation occurs in the MQL environment than a dry environment. It was observed that there was no significant difference in surface quality and chip morphology of the Al7075-T6 workpiece at different cutting speeds.

An experimental investigation of the effects of reinforcement of graphene fillers on mechanical properties of bi-directional glass/epoxy composite

Now a days Glass Fibre Reinforced Plastics (GFRPs) find their application into various industries due to their better and distinctive properties. However, these properties can be improved further by incorporating different filler materials in the glass/epoxy polymer composite. The need of the hour is to develop advanced composites with enhanced properties. Graphene has excellent properties like high absolute strength and aspect ratio and has very good potential as a nano filler due to its novelty, cost effectiveness and compatibility with other polymers. In this present investigation, the effect of graphene addition in various weight percentages 0% (S1), 1% (S2), 2% (S3), 3% (S4) on the mechanical properties of glass fiber epoxy composite were evaluated. The following tests such as flexural, tensile and impact were performed on glass/ epoxy nano composite laminates with two different lay-ups [(0/90)12s and (0/90/±45)6s]. It was observed that there was substantial increase in tensile strength and modulus, flexural strength and modulus and impact strength for both laminates with graphene reinforcement when compared to parent material having no graphene content. Experimental results showed that the highest enhancement of mechanical properties is achieved with 2 wt% (S3) of graphene addition with parent material for both lay-ups. Experimental results also showed that (0/90/±45)6s lay up exhibits better mechanical properties than (0/90)12s lay-up with similar thickness. Therefore, the present investigation showed that reinforcement of graphene with the parent material has increased various mechanical properties of glass fibre epoxy composite significantly, which makes it potentially good reinforcement in polymer composites.

Study on Ni composite coating on Al6061 substrate material with different nano particle reinforcement by electrodeposition process

The Ni composite coating has found wide industrial applications due to their anti-wear and better functional properties. The coatings generated by the electrodeposition process are popular for its economical and flexibility in its operating conditions. The incorporation of hard micro and submicron particles in the conventional coating is providing a new window for the researchers. At the same time the use of Al6061 material in automobile industries is phenomenal for its low weight high strength ratio. In the present work, the Ni coatings with different nano particles at different particle concentration are studied. The microhardness and wear properties are evaluated for different combinations of the composite coating. Further work is carried out in order to optimize the wear parameters in respect to study the influence of normal load, sliding speed, and sliding distance on the composite coating. The lower wear rate and higher microhardness is observed for the composite coating of Ni-Al2O3 compared to rest of Ni-xx coating. The presence of Al2O3,TiO2 particles restrict movement of dislocation though the weaker ZrO2 particles undergo plastic deformation with deep grooves. The debris formed between the pin sample and disc acts as the third body for abrasive nature of wear which accelerated the wear with higher load.

Effect of matrix structures on TRIP effect and mechanical properties of low-C low-Si Al-added hot-rolled TRIP steels

We applied different hot-rolling direct quenching and partitioning (HDQ&P) processes to a low-C low-Si Al-added steel and obtained eight TRIP-assisted steels with different matrix structures, viz, martensite, ferrite/bainite, ferrite/martensite and ferrite/bainite/martensite. The microstructures were characterized using SEM, TEM and XRD. The mechanical properties were investigated by means of uniaxial tensile tests. Quasi in-situ tensile tests in combination with EBSD and microscopic digital image correlation (μ-DIC) analyses were performed on microstructure regions containing ferrite, martensite and retained austenite to investigate the TRIP effect and composite effect. Considering both the chemical and strain partitioning among the structure components, we analyzed the specific influence of the matrix structures on the austenite stabilization, martensitic transformation of retained austenite and ductility of the material. The results show that the TRIP steel with a martensitic matrix exhibits high ultimate tensile strength (UTS) and yield ratio reaching up to 1200 MPa and 0.87, with the product of strength and elongation (PSE) of about 18000 MPa%. The introduction of 8%–25% (in area fraction) of ferrite leads to a decrease of the yield strength in 100–200 MPa, but without significant reduction of the UTS. The increase of the ferrite fraction to 30%–35% results in an obvious decrease of the UTS and yield ratio to about 950 MPa and 0.6. Retained austenite, with the amount of 14 vol %, was stabilized in the TRIP steel with a martensitic matrix. The introduction of ferrite (8%–35% in area fraction) and granular bainite can promote the carbon partitioning, thus enhancing the stabilization of retained austenite. The TRIP steel with a martensitic matrix exhibits a slight martensitic transformation of retained austenite because of the low deformability of the martensite. For TRIP steel with a matrix composed of ferrite and martensite, the low deformation compatibility of the soft and hard structure components also leads to a week martensitic transformation of retained austenite. The introduction of granular bainite can effectively improve the deformation uniformity and enhance the martensitic transformation during deformation. The TRIP effect and the composite effect of matrix structures jointly control the ductility of the TRIP steels. To optimize the ductility, we not only need to enhance the TRIP effect but also to improve the deformation compatibility of the matrix structures by tuning the structure components and their strength differences.

High-strength medium Mn quenching and partitioning steel with low yield ratio

ABSTRACTA new microstructural design is proposed to develop a strong and ductile quenching and partitioning (Q&P) steel with low yield ratio. This steel has a heterogeneous dual phase microstructure which is developed by varying austenite thermal stability through Mn segregation. The heterogeneous microstructure contains large austenite grains which contribute to the low yield strength. The ultra-high tensile strength and good ductility are ascribed to the enhanced strain hardening behaviour resulted from the continuous transformation-induced plasticity (TRIP) effect. The present microstructural design enables a conventional medium Mn steel with high tensile strength, good ductility and low yield ratio, which promises easy forming and potential applications in automotive industries.This paper is part of a Thematic Issue on Medium Manganese Steels.

Mechanical behaviors and texture evolution of CoCrFeNi high-entropy alloy under shear-tension deformation

The shear-tension deformation behaviors of CoCrFeNi high-entropy alloy (HEA) were investigated by introducing five groups of different inclined notches, and mainly focus on mechanical response and texture evolution. The results show that CoCrFeNi HEA exhibits significant structural sensitivity and high notch strength ratio (NSR), and the stress concentration factor Kt of specimens and stress distribution at the notch roots were acquired by finite element method (FEM). In addition, the notch strengthening effect of HEA is more obvious with the increase of shear stress component. When the shear stress component increases, the E {111}<110>, F {111}<112> and γ-fiber textures are the main texture components after deformation. The evolution characteristics of Cu-type and Brass-type textures under the shear-tension stress states are significantly different from those under the rolled state. Moreover, complex stress states have no obvious effect on Cu texture under shear-tension deformation, but a large one on CuT texture.

Role of TiC and h-BN particles on morphological characterization and surface effects of Al 4032 hybrid composites using EDM process

Aluminum based hybrid metal matrix composites (HMMCs) are utilized in myriad of applications owing to their attractive properties such as low weight to high strength ratio, enriched mechanical and thermal properties over other conventional materials. In this work, the consequence of TiC and h-BN particles on morphological characterization and surface effects of aluminium based HMMCs during electrical discharge machining (EDM) process is discussed. The HMMCs are fabricated by varying the wt. % of TiC and then EDM is done by examining the input parameters such as peak current (A), pulse on time (μs) and gap voltage (v) under L27 orthogonal array method. The performance and surface effects of the machined surface are evaluated after completing the EDM process. The MRR appears to surge with the rise in the peak current and decays with increasing the wt. % of TiC particles. Although by amplifying the wt. % of TiC particles, the size of the craters and the voids is augmented on the machined surface. Furthermore, as the peak current upsurges, the microhardness of the machined samples are augmented.