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Hyperelastic modelling of rubber with multi-walled carbon nanotubes subjected to tensile loading

Jweeg M.J., Alazawi D.A., Jebur Q.H., Al-Waily M., Yasin N.J.

Archives of Materials Science and Engineering

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2022

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Vol. 114, nr 2

69--85

EN

Purpose: This study thoroughly examined the application of inverse FE modelling and indentation tensile tests to identify nanotubes' rubber material properties. indentation tensile tests to identify nanotubes' rubber material properties. Design/methodology/approach: Carbon nanotubes with various percentages of multi-walled carbon nanotubes exposed to high tensile stress were used to enhance the mechanical qualities of N.R. rubber. Findings: In this work, carbon nanotubes have been added to natural rubber. By using a solvent casting technique, toluene was used to make nanocomposites. 0.2%, 0.4%, 0.6%, 0.8%, and 1%. In this article, rubber and multi-walled carbon nanotubes interact in practical ways. Mechanical features of carbon nanotubes in NR have been researched. The results will lead to rubber products with improved mechanical qualities compared to present nanocomposite rubber containing various percentages of multi-walled carbon nanotubes exposed to large tensile test loading. The relative fitness error for significant stresses is reasonable with a second or third-order deformation model in numerical results. Research limitations/implications: Non-linear finite element analysis is widely used to optimise complicated elastomeric components' design and reliability studies. However, accurate numerical results cannot be achieved without using rubber or rubber nanocomposite materials with reliable strain energy functions. Practical implications: The indentation tensile tests of rubber samples have been simulated and confirmed using a parametric FE model. An inverse materials parameter identification algorithm was used to calculate the hyperelastic material properties of rubber samples evaluated in uniaxial tensile. Using ABAQUS FE software, material parameters and force-displacement data may be automatically updated and extracted. Originality/value: The numerical data for the inverse method of material property prediction has been successfully established by developing simulation spaces for various material characteristics. The force-displacement curve can be represented using technical methods. The results demonstrate that the inverse FE modelling process might be simplified by using these curve fitting parameters and plot equations to build a mathematical link between curve coefficients and material properties. The first, second, and third-order deformation models were tested using FE simulations for the tensile test.

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Experimental investigations and finite element modelling of a suggested prosthetic foot

Jweeg M.J., Hassan A.K., Almudhaffa M.M.

Archives of Materials Science and Engineering

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2022

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Vol. 115, nr 1

21--33

EN

Purpose: To design and manufacture a dynamic cheap prosthetic foot compatible with amputees' requirements by introducing a natural fibre called kenaf (scientific name Hibiscus cannabinus L). Design/methodology/approach: In two cases, four suggested designs were analysed using the finite elements method (FEM) with a commercial ANSYS R1 program. The first case was a heel strike. The second was toe-off by subjecting force equal to 70 kg for both cases to select the optimal design. Findings: The foot found the tensile strength, flexural strength, impact stress, and fatigue test according to ISO 10328 standards successfully. Research limitations/implications: The selected design was analysed again using the ANSYS R1 program for weights 60, 70, and 80 kg for two sequences, one containing kenaf, to study how such additive could affect the mechanical properties and estimate the proper quality weight of the foot. The winner's design was then produced and tested in a fatigue foot tester according to ISO 10328 standards. Practical implications: The results showed that the sequence containing the natural fibres kanaf material improved the deformation by 20% for both cases (from 7.47 to 8.92 mm for the heel strike case for a weight of 80 kg for the sequence without and with kanaf, respectively), and the damping ratio increased by 50% (0. 188 and 0.273 for the sequence without and with kenaf, respectively), which means an increase in the stored energy and higher stability. Also, the mechanical properties like maximum tensile strength, flexural strength, impact stress, and natural frequency were modified. Originality/value: This paper develops an analytical and practical study to design and produce a dynamic cheap prosthetic foot made from natural fibres, which are characterized as renewable, cheap, recyclable, and environmentally friendly materials with good mechanical properties. Authors believe it is the first time to use natural kenaf fibres in the prosthetic foot manufacturing field.

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Hyperelastic models for the description and simulation of rubber subjected to large tensile loading

Jebur Q.H., Jweeg M.J., Al-Waily M., Ahmad H.Y., Resan K.K.

Archives of Materials Science and Engineering

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2021

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Vol. 108, nr 2

75--85

EN

Purpose: Rubber is widely used in tires, mechanical parts, and user goods where elasticity is necessary. Some essential features persist unsolved, primarily if they function in excessive mechanical properties. It is required to study elastomeric Rubber's performance, which is operational in high-level dynamic pressure and high tensile strength. These elastomeric aims to increase stress breaking and preserve highly pressurised tensile strength. Design/methodology/approach: The effects of carbon black polymer matrix on the tensile feature of different Rubber have been numerically investigated in this research. Rubber's material characteristics properties were measured using three different percentages (80%, 90%and 100%) of carbon black filler parts per Hundreds Rubber (pphr). Findings: This study found that the tensile strength and elongation are strengthened as the carbon black filler proportion increases by 30%. Practical implications: This research study experimental tests for Rubber within four hyperelastic models: Ogden's Model, Mooney-Rivlin Model, Neo Hooke Model, Arruda- Boyce Model obtain the parameters for the simulation of the material response using the finite element method (FEM) for comparison purposes. These four models have been extensively used in research within Rubber. The hyperelastic models have been utilised to predict the tensile test curves—the accurate description and prediction of elastomer rubber models. For four models, elastomeric material tensile data were used in the FEA package of Abaqus. The relative percentage error was calculated when predicting fitness in selecting the appropriate model—the accurate description and prediction of elastomer rubber models. For four models, elastomeric material tensile data were used in the FEA package of Abaqus. The relative percentage error was calculated when predicting fitness in selecting the appropriate model. Numerical Ogden model results have shown that the relative fitness error was the case with large strains are from 1% to 2.04%. Originality/value: In contrast, other models estimate parameters with fitting errors from 2.3% to 49.45%. The four hyperelastic models were tensile test simulations conducted to verify the efficacy of the tensile test. The results show that experimental data for the uniaxial test hyperelastic behaviour can be regenerated effectively as experiments. Ultimately, it was found that Ogden's Model demonstrates better alignment with the test data than other models.

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A new method for measurement the residual stresses in friction stir welding

Jweeg M.J., Hamdan Z.Kh., Majeed A.H., Resan K.K., Al-Waily M.

Archives of Materials Science and Engineering

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2021

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Vol. 112, nr 2

63--69

EN

Purpose: The residual stresses in different welding methods are fundemental problems to consider. Friction stir welding is one of a solid state joining process, it is economical in that it permits joining together different materials, the specimens in this method (FSW) have excellent properties of mechanical as proven by tensile, flextural and fatigue tests, also it is environmentally friendly process minimizes consumption of energy and generate no gasses or smoke. In friction stir welding , there are two kinds of generated residual stresses: tensile stress and compressive stress. So, this study measuring the residual stresses by using a new method for measuring residual stresses depends on tensile testing and stress concentration factor, this method is a simple, fast and low cost, also it is not need special device. Design/methodology/approach: In previous studies, several techniques were used to predict the value of residual stress and its location, such as destructive, semi-destructive, and non-destructive methods. In this study, a simple, new, and inexpensive way was used based on the tensile test and stress concentration of the friction stir welding (FSW). Findings: By comparing the results obtained with the previous studies using the X-ray method, with the current research, it was found that the results are good in detecting the location and value of the residual stress of friction stir welding. The value of discrepancy of the residual stress in the results between those obtained by the previous method and the current method was about 3 MPa. Research limitations/implications: There are many rotational and linear feeding speeds used in this type of welding. This research used two plates from 6061 AA with 3mm thickness, 100 mm width, and 200 mm length. The rotational speed used in friction stir welding was 1400 rpm, and the feeding speed was 40 mm/min. Practical implications: The residual stress obtained with the new method is 6.2 MPa, and this result approximates other known methods such as the X-ray method in previus studies. Originality/value: Using a new simple method for measuring residual stresses of friction stir welding depends on stress concentration factor and tensile testing. This method is fast and low cost , also it is not need specialized device, compared to other methods such as x-ray or hole drilling methods.