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1

Study of tensile, hardness, and compressive properties of prosthetic pylon made of ramie and carbon/glass hybrid composite materials

Ali M., Hashim H.A., Oleiw A.H., Mohmmed J.H.

Archives of Materials Science and Engineering

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2025

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Vol. 132, nr 1

21--28

EN

Purpose: Prosthetic pylons are the columns that connect the prosthesis to the person’s body and play a vital role in providing stability, comfort, and functional performance to prosthetic users. Improving the properties of the columns contributes significantly to enhancing the user experience. The research aims to develop prosthetic pylons’ mechanical properties using natural and synthetic fibres. Design/methodology/approach: We could achieve these objectives by performing the composite prosthetic pylon materials used to replace conventional prosthetic pylon materials made of titanium, aluminium, or stainless steel. Findings: The results demonstrated that the type and quantity of reinforcement layers had a substantial effect on the mechanical properties of laminated composites. The results showed that the samples made of two layers of synthetic hybrid (glass and carbon) fibers gave better properties in terms of tensile strength, Young’s modulus, hardness, and compressive strength were 123 MPa, 6.5 GPa, 86 shore D, and 80 MPa, respectively compared to the samples made of three layers of ramie natural fiber. At the same time, the percentage of elongation was higher for ramie reinforced composite samples. Research limitations/implications: The vacuum method was used to produce specimens with polyester as the matrix, and varying numbers of synthetic hybrid (carbon and glass) and natural (ramie) fibre layers as reinforcing materials. The mechanical characteristics (tensile strength, elongation percentage at break, Young’s modulus, compressive strength, and hardness) of each type of composite material were tested and evaluated. Originality/value: The effect of both materials gave acceptable results and proved their suitability for use instead of some metal materials that cause fatigue, exhaustion, and discomfort to users.

2

Natural frequency and critical velocities of heated inclined pinned PP-R pipe conveying fluid

Mohmmed J. H., Tawfik M. A., Atiyah Q. A.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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Vol. 107, nr 1

15--27

EN

Purpose: The flow velocity and pressure of fluid flowing through a pipeline can cause the vibration of pipes, and consequently result in the modification in natural frequency via fluid-structure interaction. The value of the natural frequency of a component when approaches the excitation force to a certain degree, a severe resonance failure may occur. Hence, avoiding the resonance failure of a pipe subjected to complex conditions is an essential issue that requires to be solved urgently in the engineering field. This work treats the transverse vibration for flexible inclined heated pipe, made of polypropylene randomcopolymer (PP-R), conveying fluid assuming pinned connections at the ends. The pipe was placed at different support angles and subjected to variant temperatures. Design/methodology/approach: The inclined pipe is modelled as Euler-Bernoulli beam taking into account its self-weight, temperature variation, inclination angle, aspect ratio, and internal fluid velocity. The integral transforms method, which includes the finite Fourier sine and the Laplace transforms, was used to develop an analytic solution to the modified equation of motion and the analytical expressions for dual natural frequencies of the pipefluid interaction system were computed. Findings: The proposed solution technique via finite Fourier sine and Laplace transforms offers a more convenient alternative to calculate the dynamic characteristic of pipes conveying fluid. The obtained results showed that the dynamical behaviour of pipe–fluid system is strongly affected by fluid flow velocity, degree of inclination, temperature variation, and aspect ratio of the pipe in transverse modes. Research limitations/implications: This work focuses on fundamental (first) mode in the most discussions. Practical implications: It was revealed that the thermal effects in the pipe are a very important factor and more significant in comparison with the internal fluid velocity and the inclination angle has a larger impact on vibration characteristics at a higher aspect ratio. The findings can be useful for the design of engineering components. Originality/value: Determining the combining effect of inclination angle, aspect ratio, and thermal loading on vibration characteristic of the pipes conveying fluid by using an improved analytic solution to the modified equation of motion via mixed of finite Fourier sine and Laplace transforms.

3

Experimental study of the mechanical and corrosion properties of ethyl silicate resin applied on low carbon steel

Ali M., Mohmmed J.H., Zainulabdeen A.A.

Archives of Materials Science and Engineering

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2021

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Vol. 108, nr 2

68--74

EN

Purpose: This work aimed at evaluating the properties of the ethyl silicate-based coating that can be applied on low carbon steel. Design/methodology/approach: Two mixture ratio types (2:1, and 3:2) of resin and hardener respectively were used to prepared two specimen models (A and B). Findings: It found that some mechanical properties (tensile, hardness, and impact strength) of ethyl silicate resin were evaluated according to standard criteria. Research limitations/implications: The effect of heat treatments at various temperatures (100, 150, and 200°C) and holding at different times (10, 20 & 30) min on hardness was investigated. Practical implications: Moreover, an open circuit potential corrosion test with a solution of 3.5% Sodium Chloride at room temperature and 60°C was used to determine the corrosion resistance of low carbon steel specimens coated with the two mixture types. Originality/value: The effects of mixture ratios (for resin and hardener) and heat treatment conditions on properties of ethyl silicate-based coating were studied. From obtained results, acceptable values of tensile, hardness, and toughness were recorded. Increasing heat treatment temperature and holding time leads to enhance hardness for both model types. An open circuit potential (OCP) tests show that there is an enhancement of protective properties of ethyl silicate coatings with mixture type B in comparison with type A was achieved. Generally, the results indicate that specimen model B has higher properties as compared with specimen model A.

4

Buckling and bending properties of aluminium plate with multiple cracks

Mohmmed J. H., Mahmood N. Y., Ali M., Zainulabdeen A. A.

Archives of Materials Science and Engineering

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2020

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Vol. 106, nr 2

49--58

EN

Purpose: In this paper, the bending strength and buckling stability of (AA 7075-T6) aluminium plate weakened by many transverse cracks, which located at different positions, subjected to concentrated loads applied at the ends were analysed. Design/methodology/approach: Numerical modelling and calculation by the finite element method (ANSYS Package), for the critical load of bending and compression panel were estimated. Findings: It found that the variation of the critical stress in bending and buckling is proportional to the crack conditions (no. of crack and location). In general, the critical load in bending and buckling decreases with increasing the crack number in structure. Research limitations/implications: For both bending and buckling, two transverse cracks on one face of plate is more stable than two transverse cracks on opposite faces. Practical implications: In addition, many experimental tests were carried out by using an INSTRON test machine to obtain the buckling critical loads, where the experimental results were compared with the ones of the finite element method. Furthermore, bending strength was calculated theoretically for the cracked panel. Originality/value: Comparison between the experimental and numerical (FE based model) data and between the theoretical and nu-merical (FE based model) data for buckling and bending strength respectively indicate the precise and the simplicity of the developed models to determine the critical loads in such cases.

5

A new high thermal shock resistant onelayer glass–ceramic coating for industrial and engineering applications

Mohmmed J. H.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 82, nr 2

70--76

EN

Purpose: A new high thermal stability single layer glass–ceramic coating system designing for applied on various grade of steel alloy has been developed in this work. Design/methodology/approach: The thermal shock resistance, thermal conductivity and thermal expansion of the coating system were evaluated by using suitable standard tests. Some crystalline agents (Lithium oxide Li2O, Titanium oxide TiO2, Zircon ZrSiO4 and Feldspar CaO∙Al2O3∙2SiO2) were add at constant ratio 6% to coating system to evaluate their effects on the resultant coatings. Findings: The results indicate the suitability of these coatings for protection of metal substrate. Also the results show that the properties of resultant coating were hardly affected by composition and concentration of crystalline agent. Research limitations/implications: Coating with lithium oxide has the lowest thermal expansion, which means the highest thermal shock resistance. While, values of thermal conductivity were too close for all types of coating. Originality/value: Generally, the resultant coating properties have been enhanced in all cases; this is associated with the introduce the crystalline agent which lead to the formation of a complex network of crystalline phases.