Corrosion fatigue of biomedical metallic alloys: Mechanisms and mitigation

A thermo-elastic contact problem of functionally graded materials (FGMs) rotating brake disk with different pure brake pad areas under temperature dependent material properties is solved by Finite Element Method (FEM). The properties of brake disk change gradually from metal to ceramic by power-law distribution along the radial direction from the inner to the outer surface. Areas of the pure pad are changing while the vertical force is constant. The ratio of brake pad thickness to FGMs brake disk thickness is assumed 0.66. Two sources of thermal loads are considered: (1) Heat generation between the pad and brake disk due to contact friction, and (2) External thermal load due to a constant temperature at inner and outer surfaces. Mechanical responses of FGMs disk are compared with several pad contact areas. The results for temperature-dependent and temperature-independent material properties are investigated and presented. The results show that the absolute value of the shear stress in temperature-dependent material can be greater than that for temperature-independent material. The radial stress for some specific grading index (n = 1.5) is compressive near the inner surface for double contact while it is tensile for a single contact. It is concluded that the radial strain for some specific value of grading index (n = 1) is lower than other FGMs and pure double side contact brake disks.

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Thermo-mechanical contact problems and elastic behaviour of single and double sides functionally graded brake disks with temperature-dependent material properties.

There have been review on kenaf fibre (KF) production and mechanical properties but lacks review on the treatment and surface modification on kenaf fibre. Therefore, this study is to show the type of treatment that have been done by previous researcher. A lot of methods have been investigated to find the optimum method to obtain better condition and properties for kenaf fibre. The present review describes those applied to kenaf fibre. The most widely used chemical treatment is the alkaline treatment using a sodium hydroxide (NaOH) solution, followed by a silane treatment. Variety of chemical concentration for NaOH solution and silane solution are investigated and a few combined treatments such as alkaline-silane, alkaline-steam, alkaline-radiation and alkaline-bleaching are also discussed. Thus, this paper presents an overview of investigated treatment methods with application to kenaf fibre and what are the effects of chemical treatment to the surface of kenaf fibre and the mechanical properties of the composites developed based on treated kenaf fibre.

Effects of fibre treatment on mechanical properties of kenaf fibre reinforced composites: a review

Tensile and fracture toughness of high strength β Titanium alloy, Ti–10V–2Fe–3Al, as a function of rolling and solution treatment temperatures

Metastable β titanium alloys are widely used in the biomedical, automotive, and aerospace industry, due to their excellent corrosion resistance, fatigue strength, biocompatibility, and easy formability. Besides all these use areas, the suitable microstructure of the alloys for heat treatment increases the efficient usability day by day. In literature research, it has been found that heat treatment types such as cryogenic treatment and precipitation hardening can be applied efficiently to the alloys. Optimum strength/ductility, wear resistance, creep strength, and fatigue strength can be obtained with these heat treatments. For this reason, it has become important to understand the effect of heat treatments on the microstructural and mechanical properties of the alloys and parameters affecting this heat treatment efficiency. Precipitation hardening includes solution and aging treatment steps. The solution treatment can be applied at temperatures below and above the β transition temperature. While the aging treatment can be applied in four different ways, in the review article, the effects of single step and duplex aging treatment, which are applied with high efficiency, are emphasized. Precipitation hardening efficiency affects the chemical composition of the alloys, heat treatment steps, treatment temperature and times, and heating/cooling rate. The cryogenic treatment provides the formation of martensite α phases in metastable β titanium alloys cooled below the martensitic transformation temperature. Higher-strength and hardness have been obtained in the studies where aging treatment was applied after cryogenic treatment. Cryogenic treatment efficiency determines chemical composition of the alloys, treatment temperature and time, the heating/cooling rates, and heat treatments applied after cryogenic treatment.

A review on heat treatment efficiency in metastable β titanium alloys: the role of treatment process and parameters

This article reviews the literature studies based on improving the mechanical properties of fibre-reinforced composites using fibre-prestressing method. The idea is characterized by pretensioning t...

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Fibre prestressed polymer-matrix composites: a review:

Finite element analysis of thermoelastic contact problem in functionally graded axisymmetric brake disks

Effect of fabric biaxial prestress on the fatigue of woven E-glass/polyester composites

The flexural properties of plain-weave woven fabric-reinforced composites have been investigated to clarify the effects of equi-biaxially fabric prestressing on flexural characteristics. The prestressed composite samples were manufactured by applying the symmetrical tension load to both warp and weft yarns prior to matrix curing. The fabricated samples were tested under different fabric orientation angles, i.e. from warp to bias direction. The decline in the flexural properties of the prestressed composite due to matrix creep was checked. From three-point bending tests, the prestressed samples exhibited a maximum increase in the flexural performance, such as the strength and modulus, of ∼16% at a prestressing level of 50 MPa when compared with unprestressed counterparts. The level of improvement in the flexural properties reduced with increasing fabric orientation angle. The creep was induced in the prestressed matrix and subsequent decline in the improved flexural properties was indicated in the prestressed samples. The decline in flexural properties occurred mostly during the short-term creep.

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Z.N. Ismarrubie

Papers

Fibre prestressed polymer-matrix composites: a review:

Finite element analysis of thermoelastic contact problem in functionally graded axisymmetric brake disks

Effect of fabric biaxial prestress on the fatigue of woven E-glass/polyester composites

The influence of equi-biaxially fabric prestressing on the flexural performance of woven E-glass/polyester-reinforced composites

Fibre prestressed composites: Theoretical and numerical modelling of unidirectional and plain-weave fibre reinforcement forms