Mechanical Performance Of Materials Research Articles

Improving pulse eddy current and ultrasonic testing stress measurement accuracy using neural network data fusion

Stress and residual stress are two crucial factors which play important roles in mechanical performance of materials, including fatigue and creep, hence measuring them is highly in demand. Pulse eddy current (PEC) and ultrasonic testing (UT) are two non-destructive tests (NDT) which are nominated to measure stresses and residual stresses by numerous scholars. However, both techniques suffer from lack of accuracy and reliability. One technique to tackle these challenges is data fusion, which has numerous approaches. This study introduces a promising one called neural network data fusion, which shows effective performance. First, stresses are simulated in an aluminium alloy 2024 specimen and then PEC and UT signals related to stresses are acquired and processed. Afterward, useful information obtained is fused using artificial neural network procedure and stresses are estimated by fused data. Finally, the accuracy of fused data are compared with PEC and UT information and results show the capability of neural network data fusion to improve stress measurement accuracy.

Adjusting the mechanical behavior of embroidered scaffolds to lapin anterior cruciate ligaments by varying the thread materials

Traumatic rupture of the anterior cruciate ligament (ACL) can cause local destabilization and loss of mobility. Reconstruction using engineered ACL grafts is rarely successful due to sub-optimal material choice and mechanical performance. Thus, the presented work demonstrates the fabrication of various embroidered single- and bi-component scaffolds made of two commercially available monofilament threads (polydioxanone, poly(lactic acid-co-ɛ- caprolactone)) as well as a novel melt spun poly(L-lactic acid) multifilament and their mechanical analysis by tensile tests and under cyclic loading. Selected scaffolds, adjusted by material composition and textile parameters, revealed a load–strain behavior comparable to native lapin ACL tissue exhibiting a sufficient amount of elastic deformation within the toe-region of 1.7%, scaffold stiffness of 123 N/mm and adequate maximum tensile load (300 N) and strain (20%). Therefore, the design of resorbable embroidered bi-component scaffolds represents a promising approach to replace artificial non-resorbable ligament grafts and allows for innovative tissue engineering strategies.

Preparation of Medical Low-Temperature Wood-Plastic Polycaprolactone Composites and their Properties

Traditional medical external fixation material represented by gypsum is brittle, heavy and prone to adverse reactions, clinical effect is not ideal. The pine wood fiber particles (size for 10 ~ 40 mesh) and polycaprolactone (PCL) are used to prepare a new kind of wood-plastic polycaprolactone composites (WPC) by the blending method. The experimental results show that the increase of PCL mass ratio can enhance the material strength and flexibility, especially the match force between the pine wood fiber particles. Meanwhile, when the mass ratio of PCL reached 65%, this enhancement effect significantly diminished; after the mass ratio of PCL reached 70%, the phenomenon of material mechanics performance decline. In this paper, the prepared WPC, which can soften under temperature 50°Cand repetitively finalize the design, have good mechanical properties, low-temperature thermoplastic and environment protection.

Development and Experiment of Viscoelasticity Measurement Device for Sponge Material

The viscoelastic property of buffer material like sponge is an important index of material mechanics performance; it is also the main basis for choosing protective material used as hip protector. In order to research hip protector to prevent the elderly femoral fractures caused by falls, a single degree of freedom forced vibration model is adopted, and a portable viscoelasticity measurement device for sponge material is designed and developed in this paper. On this basis, the performance of the device is investigated, and the experimental research on the viscoelastic property of sponge material is carried out using the device. Investigation results show that the device has characteristics such as simple structure, light weight, and it can effectively realize the material property measurement of sponge material. At the same time, the experimental results to the viscoelasticitic property of sponge material show that the viscoelastic coefficients and usually given the performance index of sponge such as density, hardness have a close relationship. With the increase of sponge material hardness, the material's ability to resist deformation increases, so the viscoelastic coefficient also increases accordingly; but the viscoelasticity of material is also associated with the composition and the structure of the material. This research has obtained the effective method for measurement of the sponge material viscoelasticity, and found the change trend of viscoelasticity to density and hardness of sponge material, that is useful for us to select material of hip protector.

Numerical and Experimental Evaluation of the Use of a Glass Fiber Laminated Composite Materials as Reinforcement in Timber Beams

Beams are structural elements present in most structures. In the case of materials commonly used in construction highlight the wood, being a renewable source material, low density and good mechanical performance. Structures built with wood, if not handled properly, can present problems that may impair the purposes for which they were designed, requiring solutions in the form of repair or reinforcement. This study aimed to assess, experimental and numerically, the mechanical performance with the employment of a glass fiber laminate composite as reinforcement in Eucalyptus grandis and Pinus elliottii wooden beams. The woods were mechanically characterized in bending, shear parallel to grain, strength compression parallel to grain and tensile parallel to grain. The fiber glass laminate composite was characterized in tensile and pullout in wood, allowing to verify the shear strength in the interface composite-wood. To check the mechanical performance of use of the reinforcement, the timber were tested experimentally and numerically according the three points static bending structural model, with the conditions: without defects, with defects and with and without the reinforcement. The results obtained proved to be efficient the use of the laminates composite as reinforcement in the wooden beams evaluated, and under the usual conditions of services, the numerical simulations have provided good approximations, demonstrating the strength of the materials being higher the active stress components.

Dynamic Load Effects of PVA Tail Sand Cement Base Composite Materials

This paper studies that dynamic load affects mechanical properties of materials about composite tail ore different replacement rate, different PVA fiber volume content and different plate thickness. The phenomenon of the tests and results showed that:1) PVA tailings cement-based composite materials has low damage, strong integrity and strong energy dissipation under dynamic loading. 2) When the volume content is 2%, material resistance effect is best. 3) The study proves that 30 mm plate have good ductility and Size effect influence the material mechanics performance. 4) PVA tailings cement-based composite materials under dynamic loads ,as tailings content increases the performance indicators reduced. So the engineering applications recommended replacement rate of the tailings is 50%.

Effect of Heat Treatment on Microstructure and Mechanical Properties of EH36 Alloy

The appropriate heat treatment process may obviously enhance the material mechanics performance, lengthens the service life of the machine parts , reduces the exploitation conditions of the material . This article uses mechanical properties test and the optical microscope research quenching and tempering comprehensive heat treatment craft is 15mm controls to thickness controlled rolling and controlled cooling (TMCP) condition tissue and the properties of the EH36 level ship plate steel influence. The result indicated that, after the heat treatment the TMCP condition ship plate steel overall performance has enhances greatly, although has the drop slightly in the intensity, but its plasticity, the low temperature impact performance all has the distinct improvement in particular.

Material Mechanical Performance about Worm Bending and Twisting Deformation for Civil Engineering

On the condition of line elastic and small deformation, more than 80% failure of the drive shaft is due to fatigue damage. It relates to the alternating stress of the drive shaft under the combination effect of bending and twisting. When drive shaft is under the combination effect of bending and twisting for civil engineering, torsion shear stress is perpendicular to bending normal stress. They can’t be simply stacked. Combining with the belt conveyor tension device of the worm transmission, first, simplify the external force; do stress analysis in horizontal plane and vertical plane respectively. Then make corresponding bending moment figure and separately calculate the internal force, stress of each basic deformation and make comprehensive bending moment figure and torque figure. Then use the application of superposition principle, the fourth strength theory to calculate worm transmission’s strength. The method makes senses to other transmission mechanism shaft bending and twisting combination strength analysis as a reference.

Influence of fibre geometry and matrix maturity on the mechanical performance of ultra high-performance cement-based composites

This paper concerns an experimental study of the influence of the geometry of the longest steel fibre and of the matrix maturity on the mechanical behaviour of an ultra high-performance multi-scale fibre reinforced cement-based composite. The following conclusions can be drawn: • Ultra high-performance cement matrix with a very low water/binder ratio continues to mature and undergoes additional densification over time. This tendency leads to a significant increase of the material modulus of rupture as the age of the material advances. • In a very dense matrix, the total number of fibres in the matrix and the specific surface of the fibre are more important parameters than the existence or not of hooks at the fibre ends . • Twisted steel fibres lead to a better material mechanical performance than steel fibres with hooks at their ends.

Research on Material Mechanical Performance of Femurs Cured by Uyghur Sand Therapy

In our research, in accordance with the traditional sand therapy practice usually held in Turpan areas, we built an indoor sand therapy laboratory in Xinjiang University. After heating the sand with a heater for one week, we obtained similar temperature in every layer of the sand to that in the sand therapy. Male rabbits were treated with the sand therapy and medication and compared with normal control. The blood, joint fluid and mechanical properties of the bones were compared. The comparison of the mechanical properties of the bone, as well as our clinical experience with the sand therapy shows the effectiveness of such a treatment.

Study on Desulfurized Gypsum-Steel Slag Composite Gelled Material Mechanics Properties

Using desulfurized gypsum and steel slag as raw material make desulfurized gypsum-steel slag composite gelled material, by adding cement, triethanolamine, aluminium sulfate, compound activator improve gelled material mechanics performance of materials. The experimental results show that when the proportion of desulfurized gypsum and steel slag for 85:15, mixing the compound activator that aluminum sulfate mixed quantity is 1%, cement mixed quantity is 3%, triethanolamine mixed quantity is 0.8%, sample’s 14d flexural strength can reach 5.83 MPa and compressive strength can reach 16.14 MPa. SEM analysis shows that a lot of C-S-H gel structure in hydration products is conducive to improve desulfurized gypsum-the strength of steel slag gelled material, reach the purpose of improving gelled material mechanics performance.

The Preparation and Properties of Natural Bamboo Fiber/Polypropylene Fiber Non-Woven Materials

Through orthogonal analysis test analyzed three main process parameters(Acupuncture frequency, acupuncture number and acupuncture depth) on the influence of the preparation of Natural Bamboo Fiber/ Polypropylene fiber non-woven materials. The results show that when Acupuncture frequency, acupuncture number and acupuncture depth are 7.8mm\550/min\6 Composite material performance is the best; Acupuncture depth for material mechanics performance influence is the largest

Study on the Material Mechanical Performance of Large Scale Self-Compacting Rock-Filled Concrete

In order to study the influence of large size aggregate on self-compacting rock-filled concrete, the compactness between self-compacting concrete (SCC) and rocks, as well as the whole workability of self-compacting rock-filled concrete, the experimental test in the present paper was carried out on the 500-ton electro-hydraulic serve testing machine and the sizes of specimens are 450mm×450mm×450mm and 450mm×450mm×900mm. The results show that the exterior damage of self-compacting rock-filled concrete specimens are different from that of standard concrete specimens; the damage sections are flat and rocks are cut through in some areas, which shows mainly bond failure at interfaces between self-compacting concrete (SCC) and rocks. The compactness inside is well and the strength of self-compacting rock-filled concrete can almost reach that of SCC, which provides theoretical basis for the application of self-compacting rock-filled concrete.

Study of the Multiaxial Fatigue Life Influencing Factors Based on the Critical Plane Approach

The tension-torsion thin walled tube specimens were used as the researching object in this paper. The method of determination to the critical plane which has the maximum normal strain and maximum shear strain was expounded. The strain state on the critical plane under non-proportional loading was analyzed, and the unified prediction model was used to calculate the fatigue life. In order to research the influence of phase difference on fatigue life under the non-proportional loading, the relation of the equivalent strain and the phase difference in different positive strain amplitude and different strain amplitude ratio were analyzed. It’s found that the dangerous phase difference which has the shortest fatigue life is in direct relation with the strain amplitude ratio. The general formula of dangerous phase difference is presented. Through the material mechanics performance and fatigue parameters of uniaxial stress state, the coefficients in the formula can be obtained and the coefficients of 15 kinds of common materials are given for practical application.

The Study on Stress Analysis of Compound Steel-Foam-Glass Fiber Reinforced Polymer (GFRP) Structure by Lock-in Thermography

The application of thermoelastic stress analysis in compound structure is particularly complicated because of the different material components, which determines the different thermoelastic effect to be depended on the different material property and mechanical performance. This paper describes a theoretical and experimental analysis on full-filed stress distribution from thermoelastic measurements and its application to determination of stress concentration for compound Steel-Foam-GFRP structure. A finite element modeling is proposed to calculate the sum of the principal stress under the condition of dynamic cyclic load. The sum of the principal stress can be measured by means of thermal stress analysis (TSA). Lock-in thermography has been applied to measure the sum of principal stress distribution of component by its high thermal resolution. In this study, Experiments were carried out with Steel-Foam-GFRP compound structure under dynamic periodic load. The thermoelastic constant is calibrated for different component of compound structure, respectively. An artificial neural network (ANN) is proposed to identify the different component stress distribution on whole compound structure. The experimental result shows that the stress distribution of compound structure can be measured and analyzed using lock-in thermography. It is found that the stress distribution of compound structure can be evaluated with good accuracies by lock-in thermography.

The interface between metallurgy and mechanics in material performance

This paper considers an important topic, and one that is often poorly understood or misinterpreted, but which is a determining factor in many aspects of the service performance of metals (and other materials). Engineering components and structures must, of necessity, provide a bridge between the macroscopic, homogeneous and generally continuum aspects of applied load and displacement, and the microscopic, heterogeneous and often non-continuum reality of material structure and behaviour. This bridge can take the form of a genuine interface between material and environment, e.g. at a surface, or can be a virtual one where the differing philosophies of design have to be merged. The interface has particular importance in circumstances where environmental influences have a key role in determining performance characteristics (e.g. creep, environmentally-assisted cracking, or corrosion), where performance is dominated by fatigue or fracture, where welding is used to join components, or where tribology plays a role. The paper focuses on the problems associated with cracking and uses case study examples drawn from engineering practice to illustrate the role of metallurgical factors in mechanical performance of materials.

Research on Structure Stress Analysis on Composite by Lock-In Thermography

The application of thermoelastic stress analysis in composite materials is particularly complicated because of the anisotropy of the material, which determines the thermoelastic effect to be depended on the material property and mechanical performance. This paper describes a theoretical and experimental analysis on full-filed stress distribution from thermoelastic measurements and its application to determination of stress concentration. The sum of the principal stress can be measured by Thermal Stress Analysis (TSA). Lock-in Thermography has been applied to measure the sum of principal stress distribution of component structure by its high thermal resolving. In this study, Experiments were carried out with GFRP composite ply and foam materials under cyclic load. The thermoelastic constant is obtained for GFRP and foam composite materials. The stress concentration is analyzed for a specimen with a hole. The experimental results show the stress distribution can be measured and analyzed using Lock-in thermography. It is found that the composite material structure stress can be evaluated with good accuracies by lock in thermography.

The CFRP Material's Mechanical Performance and Application

This paper analyzes the normal section capacity of the reinforced concrete paste with CFRP. Based on the models under different pasting conditions(U model, one layer at the bottom plus one layer of U model, two layers in the bottom), and experiments on the reinforced concrete beams with CFRP, we will analyze the failure mechanism and failure mode of reinforced concrete beams, and calculate the limit bending capacities. The results are directly applied to practical project.

Statistical Indentation Techniques for Hydrated Nanocomposites: Concrete, Bone, and Shale

Concrete, bone and shale have one thing in common: their load‐bearing mineral phase is a hydrated nanocomposite. Yet the link between material genesis, microstructure, and mechanical performance for these materials is still an enigma that has deceived many decoding attempts. In this article, we advance statistical indentation analysis techniques that make it possible to assess, in situ, the nanomechanical properties, packing density distributions, and morphology of hydrated nanocomposites. These techniques are applied to identify intrinsic and structural sources of anisotropy of hydrated nanoparticles: calcium–silicate–hydrate (C–S–H), apatite, and clay. It is shown that C–S–H and apatite, the binding phase in, respectively, cement‐based materials and bone, are intrinsically isotropic; this is most probably due to a random precipitation and growth process of particles in calcium oversaturated pore solutions, which can also explain the nonnegligible internanoparticle friction. In contrast, the load‐bearing clay phase in shale, the sealing formation of most hydrocarbon reservoirs, is found to be intrinsically anisotropic and frictionless. This is indicative of a ‘smooth’ deposition and compaction history, which, in contrast to mineral growth in confined spaces, minimizes nanoparticle interlocking. In all cases, the nanomechanical behavior is governed by packing density distributions of elementary particles delimitating macroscopic diversity.

Mechanical performance of cyanate ester based insulation systems under ITER relevant conditions

Epoxy based glass fiber reinforced composites are candidate insulation systems for the superconducting magnet coils of fusion devices, e. g. of ITER. Because of their relatively low radiation hardness, the radiation-harder cyanate ester based systems have become of special interest for application in ITER and future fusion devices.This paper presents recent results obtained on pure cyanate ester and cyanate ester/epoxy blends reinforced with R-glass fibers/Kapton H foil. The systems were investigated at 77 K prior to and after irradiation at ambient temperature (340 K) to a fast neutron fluence of 1 × 1022 m−2 (E > 0.1 MeV) in the TRIGA reactor (Vienna). The mechanical material performance was characterized under static load conditions in tension and interlaminar shear. In addition, tension-tension fatigue measurements were carried out to simulate the pulsed operation of ITER and to assess the lifetime performance of these materials. The results show only slight mechanical degradations (by about 5 to 10%) after irradiation.