Alloy Fibers Research Articles

Plastic deformation behavior of aluminum alloy fiber porous body and its filled tube under impact loading

The size of aluminum alloy fiber wire with a short side of 5mm, a long side of 10mm and an arc radius of 1mm were prepared from the raw material of 6061 aluminum alloy fiber with diameter of 0.15mm by Spring machine cutting, namely the structure size of 5×10mm bending aluminum alloy fiber. The aluminum alloy fiber porous body with different porosity were prepared by vacuum hot pressing sintering furnace, and it was sleeved with 6063 aluminum alloy round tube to prepare aluminum alloy fiber porous body filled tube. The impact test was carried out with drop hammer impact testing machine, The plastic deformation behavior of aluminum alloy fiber porous body and its filled tube under impact loading with different porosity was studied. The results show that the impact process of aluminum alloy fiber porous body can be divided into three stages: plastic platform stage, densification stage and unloading stage, the filled tube with aluminum alloy fiber porous body can be divided into four stages: elastic deformation stage, progressive buckling stage, densification stage and unloading stage. Low porosity will make more fibers, and more benefit the generation of the sintering necks, the plastic deformation strength increases with the porosity decrease. The coupling effect of the aluminum alloy tube and the aluminum alloy fiber porous body makes the filled tube absorb the same energy with shorter impact displacement, and has stronger impact resistance and better mechanical properties.

Plastic deformation behavior of bending aluminum fiber porous material under compressive load

The 6061 aluminum alloy wires with diameters of 0.15 mm and 0.20 mm were cut into different structural sizes of 5 × 10 mm and 10 × 15 mm by a spring machine to bend the aluminum alloy fibers, one is 5 mm short side, 10 mm long side, and 1 mm arc radius, and the other is 10 mm short side, 15 mm long side, and 1 mm arc radius. Special cylindrical molds are used to prepare folding sheets with different porosities using vacuum hot pressing sintering technology. Bent aluminum fiber porous material. The gas displacement method was used to detect the pore size and pore size distribution, and the Plastic Deformation Behavior were analyzed by quasi-static uniaxial compression test. Research shows that the material presents a three-stage stress-strain curve, from the initial nonlinear elastic deformation stage to the pseudo-platform stage and the densification stage, the wire diameter and structure of the material The smaller the size, the more conducive to the densification of the silk skeleton, and the smaller the average pore size formed, the higher the compressive strength.

On the efficiency of induced prestressing in SMA mortar beams through different thermal stimuli

This paper investigates the efficiency of prestressing effect on the flexural performance of reinforced mortar beams through different heating methods. To this end, different specimens reinforced by 1.0% and 1.5% volume fractions crimped shape memory alloy fibers as well as diverse internal and external heating sources are employed. Time-deflection relationships during heating and cooling of specimens are extracted to evaluate the amount of induced prestressing force in each specimen via different heating process. Upon developing prestressing force in the reinforced mortar beams, we carry out several three-point bending tests to study the flexural behavior of mortar beams and compare the material parameters with the reinforced specimens in the absent of prestressing force. The results show that internal heating source using electric current in comparison with external heating via heat gun could be faster and more uniform across the beams cross section contributing to a higher potential capacity in terms of stimulating recovery stress and subsequently boosting ductility and toughness of the composites.

Effect of heat treatment and end-hook geometry on pullout behaviour of heavily cold worked superelastic NiTi shape memory alloy fibres embedded in concrete

In this study, superelastic fibres were fabricated from heavily cold worked shape memory alloy (SMA) wire followed by heat treatment, with the goal of enhancing fibre pullout performance and simplifying the fibre production process. The effects of annealing at 350 °C, 450 °C, and 550 °C for 20, 40, and 60 min on the tensile properties of the cold worked SMA were studied. Monotonic and cyclic single fibre pullout tests were conducted using an embedment length of 30 mm. The fibres had straight, 3D, 4D, and 5D end-hook geometries and were embedded in normal strength (NS), high performance (HP), and ultra-high-performance (UHP) concrete. The results demonstrated that heat treatment at 350 °C for 20 and 40 min produced significantly higher peak load, pullout energy, average bond strength, and equivalent bond strength values as compared to the properties of fibres exposed to other temperatures and durations. Heat treatment at 350 °C for 40 min showed the highest re-centring and cumulative energy dissipation under cyclic pullout. Pullout performance significantly increased when either mechanical anchorage or concrete strength were increased. Among the SMA fibre geometries, 5D in NS concrete, 4D and 5D in HP concrete, and 3D and 4D fibres in UHP concrete generated sufficient resistance for martensitic transformation that resulted in a significantly higher re-centring ratio and cumulative pullout energy under cyclic loading than was observed for their steel counterparts.

Influences of Anisotropic Equivalent Field and Magnetic Damping Coefficient on Giant Magnetoimpedance Effect of Cylindrical Alloy Fibers: Theoretical Magnetoimpedance Calculations

In this paper, the giant magneto-impedance (GMI) model of a cylindrical alloy fiber was established by the Maxwell equation and Landau–Lifshitz equation to simulate the influence of physical parameters of cylindrical alloy fiber on GMI under different control parameters. MATLAB was employed to calculate the magneto-impedance of cylindrical fibers and draw its curves. We found that when the anisotropic equivalent field of the fiber changes from 10Oe to 50Oe, the peak position of the GMI ratio also moves from about 10Oe to 50Oe, and the peak value gradually increases from 100% to 300%. The GMI ratio increased rapidly with the decrease in the magnetization damping coefficient. Our findings could further guide the design of supersensitive micro GMI sensors by optimally regulating the magnetic damping coefficient, the angle between the external magnetic field and easy axis and the anisotropic equivalent field of cylindrical alloy fibers.

Research on the gas–solid corrosion characteristics of 316L alloy fiber filter bags in halogen hydride atmosphere

AbstractIncineration is an effective means of solid waste disposal, but the acidic components in the complex flue gas generated by incineration put pressure on the dust removal, which also puts higher requirements on the corrosion resistance of the filter media. In this work, aiming at the gas–solid corrosion characteristics of 316L alloy fiber filter bag, the corrosion behavior of 316L alloy fiber filter materials in halogen hydride atmosphere was studied using fixed‐bed simulation corrosion experiments, and the mechanical properties of the filter materials after corrosion were analyzed. For the 316L alloy fiber filter bag, the influence of flue gas composition (O2 and H2O) and its concentration on the corrosion characteristics was explored. The corrosion mechanism was studied by combining the microscopic morphology and element distribution of the filter material before and after corrosion. The results show that halogen hydride has a significant corrosive effect on 316L alloy filter material, especially the catastrophic damage of 316L alloy fiber filter material in oxygen‐containing atmosphere. The addition of H2O has an obvious inhibitory effect on the reaction. Due to the circulation of the corrosive gas source, the mechanical properties of the 316L alloy fiber filter material were severely damaged and the tensile strength was greatly reduced.

Uniaxial compressive behaviour of mortar cylinders reinforced with crimped NiTi shape memory alloy fibres

This study investigated the axial compressive behaviours of cement mortar reinforced with crimped shaped memory alloy (SMA) fibres produced by cold drawing. The performance of the crimped fibre was investigated in term of tensile behaviour, deformation recovery, recovery stress and pullout behaviour. After that, compressive tests of mortar reinforced with two types of SMA fibres, namely, dog-bone-shaped fibres and crimped fibres, were conducted to compare their compressive behaviours. The results showed that both types of SMA fibres increased the compressive strength of mortar, and a 1.0% volumetric ratio of SMA fibres is effective to increase the compressive strength of mortar, whereas a 0.5% volumetric ratio did not significantly increase the compressive strength. The recovery stress of the SMA fibres induced by the shape memory effect does not significantly increase the compressive strength of mortar. However, when crimped SMA fibres with a 1.0% volumetric ratio were heated and recovery stress was induced, they controlled volume expansion more effectively after cracking than crimped SMA fibres without recovery stress. The findings indicate that crimped SMA fibre with recovery stress can provide crack-bridging capacity.

Damaged composite structural strength enhancement under elevated thermal environment using shape memory alloy fiber

Damaged composite structural strength enhancement under elevated thermal environment using shape memory alloy fiber

Mechanical Behavior of Shape Memory Alloy Fibers Embedded in Engineered Cementitious Composite Matrix under Cyclic Pullout Loads.

The incorporation of superelastic shape memory alloy (SMA) fibers into engineered cementitious composite (ECC) materials can provide high seismic energy dissipation and deformation self-centering capabilities for ECC materials. Whether the SMA fibers can be sufficiently bonded or anchored in the ECC matrix and whether the mechanical properties of the SMA fibers in the ECC matrix can be effectively utilized are the key scientific issues that urgently need to be studied. In order to study the mechanical behavior of SMA fiber embedded in ECC matrix, four groups of semi-dog-bone pullout specimens were fabricated, and the cyclic pullout tests were conducted in this paper. The pullout stress, displacement, and self-centering capability were analyzed, and different influencing factors were discussed. The results show that the knotted ends can provide sufficient anchorage force for SMA fibers, and the maximum pullout stress of SMA fiber can reach 1100 MPa, thus the superelasticity can be effectively stimulated. The SMA fibers show excellent self-centering capability in the test. The minimum residual deformation in the test is only 0.29 mm, and the maximum self-centering ratio can reach 0.93. Increasing bond length can increase the ultimate strain of SMA fibers with knotted ends, but reduce the maximum pullout stress. Increasing fiber diameter can increase both the ultimate strain and the maximum stress of knotted end SMA fibers. While neither bond length nor fiber diameter has significant effect on the self-centering ratio. This paper provides a theoretical basis for further study of the combination of SMA fibers and ECC materials.

ADN Solid Propellants with High Burning Rates as Booster Material for Hypersonic Applications

AbstractRAM‐ and SCRAM‐Jet engines can not generate static thrust and only work at high speeds. This starting velocity of the motor v0 is usually generated by carrier rockets or boosters, which mostly use solid propellants based on ammonium perchlorate (AP) and hydroxyl‐terminated polybutadiene (HTPB). Modern solid propellants based on ammonium dinitramide (ADN) and Glycidyl Azide Polymer (GAP) have significant advantages in terms of environmental compatibility and thermodynamic performance. In the present work, it is shown that the already high burning rate of ADN solid propellants can be more than doubled by means of metallic fibers, which significantly increases the thrust of such engines. In order to achieve such results, 3 wt% of Al−Mg alloy fibers are added to the propellant. A formulation with 3 mm long fibres shows the highest burning rate with 84.0 mm/s at 26.5 MPa. Small scale motor tests confirm these investigations. The burning mechanism is studied by SEM/EDX investigations and by measuring the thermal conductivity. These show that the fibres remain on the burning surface and thus transfer the heat from the flame to the depth of the propellant. The thermal conductivity of samples with AlMg5 fibers is about 22 % higher than the reference.

Vibration and noise reduction of pipelines using shape memory alloy

Abstract In this article, the pipeline design is introduced. The new pipe structure is made of new fiber metal laminates with the unidirectional composite and sheet metal (Ti–Ni alloy). Many pipe structures are in the heating environment such as in or around the engine, which will also cause the heating-up structure. If the shape memory alloy (SMA) fiber is added to the composite lamination, it can be seen that with the increase of temperature, the stiffness of the structure is increased and so is its frequency. The changed frequency of the structure can avoid the excitation frequency in this way, which effectively inhibits the resonance. In dynamic analysis, it can also show that the pipeline with the SMA fiber has good performance for vibration reduction and noise attenuation. Additionally, the convergence of the meshing model and the effect of the thickness of the SMA material on vibration and noise reduction are also discussed.

Interfacial bonding mechanism and mechanical properties of adding CuZn alloy fibre for Cu/Al composite

The heterogeneous interface constituted by Cu and Al were diffusion-bonded with CuZn alloy fibre interlayer under different bonding parameters, which was compared with directly bonded Cu/Al interface to analyze the effects of the different intermetallic compounds (IMCs) occurred at the joining interface on the interface mechanical properties. The interface microstructure was analyzed by scanning electron microscope (SEM), the compositions profiles across the joining interface were measured by energy dispersive spectroscopy (EDS), the phase and grain in the bonding interface of a Cu/Al bond were carefully investigated via electron backscatter diffraction technique (EBSD), the results show that the interface phase of Cu/Al composites grows irregularly, which leads to the low uniformity of interface properties. By adding CuZn alloy fibre, the interface of Cu/Al shows cellular skeleton and promotes the uniform diffusion of interface. When the bonding time was 570 °C for 60 min, the average shear strength of Cu/CuZn/Al interface reached 60.7 MPa. Compared with Cu/Al interface, the standard deviation of shear strength decreased from 18.7 to 1.6, and the variance decreased from 3.7 to 1.1. • The diffusion of Cu and Al was promoted by the introduction of Zn. • CuZn alloy can improve the interface homogeneity of large area Cu/Al composites. • When CuZn alloy fibre was added, the fracture mode changed to mixed fracture. • The bonding time has a great effect on the uniformity of the interface.

Effect of shape memory alloy fiber content and preloading level on the self-healing properties of smart cementitious composite (SMA-ECC)

Shape memory alloy (SMA) fibers are used in engineered cementitious composite (ECC) to achieve good self-healing properties in the newly developed smart cementitious material (SMA-ECC). This study focuses on the effect of SMA fiber content and preloading level on the self-healing properties of SMA-ECC through a two-stage four-point bending test. The self-healing effect was evaluated in terms of recovery of cracks, mechanical properties, and internal damage before and after self-healing. The results showed that the efficiency of the healing of cracks reduced with the increase in the width of the initial cracks. Cracks less than 50 µm width can be healed in SMA-ECC, while cracks larger than 200 µm width were the upper limit for the healing. The efficiency of the self-healing in terms of crack closure increased significantly with increasing SMA fiber content from 0.3% to 0.7% but did not change obviously when SMA fiber content increased from 0.7% to 1%. The recovery of flexural properties and damage decreased significantly with increasing preloading level. A high SMA fiber content was required for self-healing behavior at a high preloading level. At the pre-loading ratio of 50% and 70%, the recovery of flexural properties reached the maximum at the SMA fiber content of 0.7%. But at the pre-loading ratio of 90%, the recovery of flexural properties increased with increasing fiber content.

Comparative life cycle assessment of safety shoes toe caps manufacturing processes

Toe caps are fundamental components of safety footwear used to prevent injuries, which can be caused by falling objects. They can be realized by exploiting different materials (metal, composites, and polymers) and manufacturing processes (stamping, injection molding, compression molding, etc.). However, they have always to fulfill the stringent requirements of safety regulations. In addition, in order to guarantee ergonomic use, they must be as light as possible. It was estimated that at least 300 million pairs of safety footwear, with 600 million of toe caps, end up in landfill or are incinerated every year. This huge amount of wastes generates a high environmental impact, mainly attributable to toe caps manufacturing processes. In this context, it is important to develop new solutions aimed at minimizing the environmental impacts of toe caps manufacturing processes. Furthermore, the reuse of carbon fiber prepreg scraps has been recognized as a valid method to produce effective toe caps. In this paper, the life cycle assessment (LCA) methodology was exploited to perform a detailed analysis of the environmental impacts associated with toe caps obtained by reclaiming prepreg scraps. The results, in terms of cumulative energy demand, global warming potential, and ReCiPe endpoints, were compared to those obtained by LCA of toe caps in steel, aluminum alloy, polycarbonate, and glass fiber reinforced composite. The analysis demonstrated that toe caps in steel present the lowest environmental footprint but they are the heaviest ones. The reclaim process for carbon fiber prepreg scraps can be a valid alternative to produce sustainable and lightweight toe caps for safety footwear.

Experimental Study on Self-Centering Performance of the SMA Fiber Reinforced ECC Composite Beam.

The combination of superelastic shape memory alloy fibers and ECC materials can form a new SMA fiber reinforced ECC composite material (SMAF-ECC) with good self-centering performance. In order to study the self-centering performance of the new composite material, 6 groups of pre-notch beam specimens were made for three-point bending cyclic loading tests, and the failure phenomenon, hysteresis curve, self-centering effect and influencing factors of the specimens were analyzed. The research results show that when the SMA fibers are effectively anchored in the ECC matrix, the SMA fibers can exert the superelastic properties to provide the ECC beams with recoverying force, and realize the crack self-closure and deflection self-recovery function for the beams, with the minimum residual crack width and deflection is only 0.9 mm and 1.3 mm respectively. Increasing fiber content can cause a small increase in the self-centering ability of the beams. However, only when the fiber diameter is appropriate, better self-centering effect can be achieved, but the difference caused by fiber diameter in the test was only 5%. SMA Fiber end forms have significant influence on self-centering performance. The knotted end beam can get a more than 70% self-centering ratio, while the straight end beams and bended end beams have no self-centering ability. The research results provide important reference for the research and application of this new self-centering materials and their structures.

Hydrothermal in situ growth and application of a novel flower-like phosphorous-doped titanium oxide nanoflakes on titanium alloy substrate for enhanced solid-phase microextraction of polycyclic aromatic hydrocarbons in water samples

A novel flower-like phosphorous-doped titanium oxide nanocomposite coating was in situ grown on nickel-titanium alloy (NiTi) fiber by hydrothermal treatment in phosphoric acid solution. The experimental results demonstrated that phosphorous-doped titanium oxide nanoflakes (P-TiONFs) with an average thickness of 80 nm were formed on the NiTi fiber substrate in 0.1 mol L−1 H3PO4 at 150 °C for 6 h. Thereafter, the resulting P-TiONFs were used as SPME fiber coatings for the adsorption of typical aromatic analytes from environmental water samples, which were determined by HPLC-UV. These P-TiONFs exhibited good adsorption selectivity for hydrophobic PAHs. After optimizing microextraction conditions, linear responses were achieved in the ranges of 0.05–200 μg L−1 for the determination of PAHs with determination coefficients higher than 0.999. LODs (S/N = 3) ranged from 0.009 to 0.132 μg L−1, while LOQs (S/N = 10) ranged from 0.030 to 0.441 μg L−1. RSDs for intra-day and inter-day analyses with a single fiber varied from 4.46% to 5.56% and 5.14%–6.75%, respectively. The relative recoveries of 83.60%–119.0% were achieved for the determination of PAHs in real water samples spiked at the concentration levels of 5.0 μg L−1 and 10.0 μg L−1 with RSDs below 7.38%. In addition, the fibers exhibited no significant decrease in adsorption efficiency after being used 240 adsorption and desorption cycles. The proposed method was successfully applied to the selective enrichment and determination of target PAHs in different water samples.

Flexural toughness and compressive stress–strain behaviour of pseudoelastic shape memory alloy fibre reinforced concrete

The results of experimental analyses for the full-range compressive and flexural response of concrete reinforced with pseudoelastic shape memory alloy fibres (PSMAFs) are discussed in this paper. PSMAFs were manufactured with two types of end hooks and were used in four different fibre contents ranging between 0.5% and 1.25%, with an interval of 0.25% by volume. Cracking patterns and full-depth crack width profiles of PSMAFs reinforced concrete (PMSA-FRC) were also generated by the 2D digital image correlation (DIC) technique. The results obtained for PMSA-FRC are compared with those of steel fibre reinforced concrete (SFRC).The flexural responses of PSMA-FRC and SFRC were significantly different at fifferent stages of flexural behaviour. Compared to SFRC, PSMA-FRC showed lower flexural strength but considerably higher flexural toughness and deflection capacity. PSMA-FRC also exhibited slightly lower compressive strength (5-8%) and modulus of elasticity (4–10%) than SFRC. However, no significant difference was noticed between PSMA-FRC and SFRC regarding the overall shape of the compressive stress–strain curve, compressive toughness and failure mode. It is also shown that PSMAFs type 2, the fibre with 45° end hook, is more efficient in distributing stress over a larger cementitious matrix area. DIC analyses displayed better control over cracking, improved multiple-cracking performance, and tighter crack profiles for PSMAFs type 2 at all four fibre contents tested in this study.

Effect of Pore Defect Size and Location on Damage Tolerance of Aluminum Alloy Piston and Fiber Ring Groove

The defects of high-power density piston aluminum alloy components involved in this paper include surface crack, internal crack, shrinkage cavity and cold shut. The service condition of piston components is 350°C-420°C, and the explosion pressure of piston crown is 28Mpa. The requirements for eddy current flaw detection of this component are in accordance with a and requirements in GB / T5126-2013 eddy current flaw detection standard, that is, it is not allowed to be greater than 0.12mm × 0.2mm × 3mm volumetric defects, and Ф1.0mm flat bottom hole equivalent point defect. For the piston components of 88kw / L high-power diesel engine, under the service conditions of temperature 350°C-420°C and piston top explosion pressure 28Mpa. Under the condition of thermal mechanical coupling, the typical NDT defects such as surface crack, internal crack, shrinkage cavity and cold shut of the first ring groove and internal position of the piston are studied. On scale, morphology and position sensitivity and their quantitative relationship. At the same time, numerical simulation analysis combined with relevant experimental verification is used to comprehensively analyze and evaluate the damage tolerance of defects, and scientifically evaluate the defects of different properties and sizes.

Research on flexible skin technique for adaptive bump inlet structure

PurposeAdaptive bump inlet can adaptively change the shape of inlet bump surface according to the flight speed of aircraft, ensuring that the inlet has good inlet-engine match performance in a wide speed range. This paper aims to use a composite flexible skin reinforced by shape memory alloy (SMA) fiber as the deformable structure at bump surface to realize the adjustable bump surface of adaptive bump inlet.Design/methodology/approachAccording to the deformation and load-bearing requirements of adaptive bump, SMA is applied to the design of adaptive bump inlet due to its characteristic of super-elasticity. A kind of SMA fiber is studied. A composite flexible skin reinforced by SMA is proposed, and its mechanical properties are analyzed. On this basis, an adaptive bump inlet is designed in which the composite flexible skin reinforced by SMA is used as bump surface, and the shape of the bump surface is adjusted by way of pressuring. The design scheme and specific parameters of the adaptive bump are given.FindingsAn adaptive bump surface that meets the design requirements of the inlet is designed, which can effectively adjust the inlet throat area with a throat area change rate of 20%.Originality/valueAn adaptive bump inlet with composite flexible skin as a deformable structure at bump surface is designed, and SMA is applied as the reinforcing fiber.

Pullout behaviour of shape memory alloy fibres in self-compacting concrete and its relation to fibre surface microtopography in comparison to steel fibres

Superelastic nickel-titanium shape memory alloy (SMA) can recover large strains. Hence, SMA fibres (SMAFs) have been incorporated into concrete to provide re-centring and crack-closing ability to the concrete. Since the structural performance of fibre-reinforced cementitious composites is significantly influenced by the fibre pullout mechanism, this research was focused on the pullout behaviour of SMAFs and their associated parameters. Single fibre pullout tests were performed on straight and hooked-end SMA and steel fibres (SFs) embedded in self-compacting concrete. The experimental investigation considers three variables: the type of hooked-end, embedded length, and loading rate. The full range of pullout load-slip behaviour was obtained under two different loading rates. The results were analysed in the slip corresponding to maximum pullout load, maximum tensile stress induced in fibre, material use factor, pullout energy, average and equivalent bond strength. Straight SMA fibres showed a weaker interfacial bond with concrete than steel counterparts. SMA fibre with 45° hooked-end showed the highest bond strength among SMA fibres considered in this study. The increase in the embedded length of most of SMAFs and SFs caused a significant increase in the pullout load without changing the configuration of the pullout load-slip curve. The pullout behaviour of SMAFs was almost rate-insensitive, whereas SFs exhibited evident rate sensitivity in the pullout. The observed differences between SMA and steel fibres were clarified based on fibre surface micro-topography and roughness and matrix damage. This difference was explained based on the surface micro-topography of fibres and matrix damage.