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1

Comparison of Tensile Properties of Nb Grain Refined A206 Alloy by Gravity and Tilt Casting

Palamutcu Nuri, Dizdar Kerem Can, Sahin Hayati, Dispinar Derya

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 4

49--53

EN

Turbulent filling of a mould is one of the ways to introduce extrinsic defects into the cast part that could deteriorate many properties of any casting. The turbulence can be easily eliminated by counter gravity casting. In gravity casting, tapered downsprue, tapered runner is needed such that the mould cavity is filled counter-gravity from the bottom which is the only best way to eliminate turbulence during filling. Tilt casting method also exists which has the potential to quiescently transfer the liquid into the mould cavity. In this work, gravity and tilt casting methods were used to evaluate the tensile properties of Nb grain refined 206 alloy. Three different Nb contents were investigated: 0.025, 0.05 and 0.1 wt% ratios and it was found that 0.05 wt% revealed the highest tensile properties. On the other hand, when the intrusion of surface folded oxides was eliminated during filling, it was found that mechanical properties were increased significantly, and particularly, the toughness was increased by two folds when tilt casting was applied compared to gravity casting.

2

Tensile fault dislocation in an irregular-layered elastic half-space

Savita, Sahrawat Ravinder Kumar, Malik Meenal

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 3

171--198

EN

In the present paper, an analytical solution for the static deformation of a two dimensional model consisting of an infinite homogeneous isotropic elastic layer of uniform thickness placed over an irregular isotropic elastic half-space due to movement of a long tensile fault has been obtained. The rectangular shaped irregularity is assumed to be present in the lower half-space and assuming that the fault lies in the elastic layer at a finite depth say ’h’ to the upper surface of the layer. For numerical computation, the expressions of displacements and stresses are calculated by using Sneddon’s method and the effect of source depth and irregularity on the displacements and stresses has been investigated graphically.

3

Designing a Three-Dimensional Woven Fabric Structure as an Element of a Baby Stroller

Bethalihem Samuel T., Barburski Marcin, Lemmi Tsegaye Sh.

Autex Research Journal

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2022

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Vol. 22, no. 2

148--154

EN

A baby stroller allows the transportation of a child over long or short distances. The materials used to produce the stroller make it heavy for users, which creates difficulties when lifting the stroller. The goal of this project was to design and fabricate a three-dimensional (3D) fabric structure that can be used as part of a stroller seat to improve its mechanical and physical properties. The idea of implementing a woven 3D system allows the development of an egg-shaped or shell-like structure as part of a stroller seat. The combination of double-woven material and honeycomb polypropylene (as the reinforcing material) was used to create a 3D composite structure. Single and double layers of polypropylene honeycomb sandwiched within layers of linen flax fabric were used to prepare the composite samples. Subsequently, tests on mechanical and physical properties, such as density, flexural strength, and tensile strength, were carried out. Analysis of the results showed that the composite with one layer of honeycomb has half the density of polyvinyl chloride.

4

Natural filler based composite materials

Nayeeif A.A., Hamdan Z.K., Metteb Z.W., Abdulla F.A., Jebur N.A.

Archives of Materials Science and Engineering

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2022

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Vol. 116, nr 1

5--13

EN

Purpose: The first goal is to get rid of waste and reduce environmental pollution, and the other goal is to investigate the effect of these fibres on properties (resistance of composite materials for bending and tensile testing) of polyester and use them in applications. Also, The moisture environment effect on the properties of composite materials was studied. Design/methodology/approach: It uses natural fibres, which are considered waste, namely eggshell and sawdust with polyester. Several samples were prepared with different weight percentages (30% and 40%), and their mechanical properties were studied and immersed in water for 15 days. And studying the effect of water on these properties. It was found that it is possible to use these fibres (waste) with polyester and benefit from them. It was found that when adding fibres to polyester, the tensile strength decreases, but the bending increases the strength. Finally, it was found that when the samples are immersed in water, the material weakens, and its mechanical properties decrease. Findings: It can be noticed that adding natural fibres by 40% and 30% improved the mechanical properties of polyester in the bending test, where the bending test increased with increased volume fraction of fibre. It can be noticed that adding natural fibres by 40% and 30% decreased the mechanical properties (tensile strength) of polyester in a tensile test. When the natural composite materials were treated with water for 15 days, water decreased the mechanical properties in bending and tensile test. Research limitations/implications: One of the limitations of this research that was found through the work is that when increasing the weight ratios of the fibres added to polyester leads to the failure of polyester, so we recommend using lower weight ratios of fibre. Practical implications: One of the limitations of this research that was found through the work is that when increasing the weight ratios of the fibres added to polyester leads to the failure of polyester, so we recommend using lower weight ratios of fibre. Originality/value: The original value of this research is the use of fibres that are considered waste, their reuse, and utilization in some applications that do not require composite materials with high mechanical properties.

5

Study on mechanical properties of notched steel wire under tension and bending

Fei Hongyu, Sun Quansheng, Yang Jianxi

Archives of Civil Engineering

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2022

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Vol. 68, nr 4

467--480

EN

The fracture reason of steel wire cable is complex, and the corrosion and local bending effect of anchorage end of steel wire cable under tension are one of the main factors. Taking the steel wire of an arch bridge cable as the research object, the notch method was used to simulate the corrosion pits on the surface of the steel wire, and the tension and bending mechanical properties of the high strength notched steel wire were tested. The bending finite element model of the high strength steel wire was established by ANSYS WORKBENCH, and the tension and bending mechanical properties of the notched steel wire under different vertical loads and pretension were studied. The test and calculation results show that the test data are close to the finite element calculation results and the variation law is consistent. Under the same vertical load, the deformation of steel wire notch decreases with the increase of pretension; The stress at the bottom of the notch is the largest at 180° direction and the smallest at 90° direction of the vertical load. Under the same vertical load and pretension, the stress of spherical shape at the notch is the largest, followed by ellipsoid shape, and groove shape is the smallest, and there is a high stress zone at the edge of groove shape. When the pretension is applied, the initial stress increases with the increase of pretension, while the stress at the notch caused by bending decreases with the increase of pretension.

6

The role of water content in rate dependence of tensile strength of a fine-grained sandstone

Cai Xin, Cheng Chuanqing, Zhao Yuan, Zhou Zilong, Wang Shaofeng

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e58, 2022

EN

Rocks in nature are commonly in partially saturated conditions and exposed to dynamic loads. In this study, to explore the coupled effects of water content and loading rate, dynamic Brazilian disc experiments were conducted on Yunnan sandstone samples with four levels of water content (from air-dried to water-saturated) under various loading rates (from 100 to 600 GPa/s) using a split Hopkinson pressure bar. The test results show that for each water content, the dynamic tensile strength of sandstone is positively sensitive to loading rate. The rate dependence of tensile strength increases as the rise of water content. The change trends of tensile strength against water content depend on loading rate: as water content rises, the tensile strength displays the manner of “no change followed by fast drop” at loading rates of 10–4 and 100 GPa/s. However, when the loading rate is above 200 GPa/s, the tensile strength increases first and then declines. The turning point occurs at water content between 1.0 and 2.0%. These observations can be interpreted with the competition between water weakening and enhancing effects under different loading conditions.

7

Study on the mechanical behaviors and failure mechanism of polyurethane cement composites under uniaxial compression and tension

Yilin Pi, Wenhua Zhang, Wanting Zou, Yunsheng Zhang

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e18, 2022

EN

The brittle nature of concrete limits the further development, while the addition of polymer can enhance the toughness and improve the working performance. Understanding the mechanical properties and failure mode of polyurethane cement composites (PUCC) is of great significance in the field of construction engineering. To solve these issues, in this paper, the tensile and compressive properties are studied. The tensile/compressive strength, elastic modulus, toughness, strain capacity and the failure mechanism were analyzed. The results showed that compared with the reference group (RF), the compressive strength of PUCC was decreased by 33%. However, rubber powder could enhance the toughness of samples up to 1.19 times than RF. Polyethylene fiber was hard to disperse because of the poor fluidity of the matrix, therefore, the mechanical properties of PUCC did not change obviously. But due to the bridging effect of fiber, the failure mode was relative intact. Not only the irregular shape of basalt would decrease the interfacial adhesion, but also the polyurethane has weakened the cohesion. The mechanical properties of concrete were reduced because of the formation of interfacial transition zone between basalt and cement matrix. Therefore, the tensile and compressive strength was decreased by 19.7% and 11.8%, respectively. Moreover, the incorporation of basalt shortens the deformation time and intensifies the failure degree of the specimen. Moreover, this study takes a three-stage model to describe the compressive stress–strain behavior of PUCC. There is a good correlation between the constitutive model and the experimental results, and the simulation is accurate.

8

Influence of adhesive on dynamic performance of steel/Al electromagnetic clinched joints

Liao Yuxuan, Zhong Jiabao, Li Guangyao, Cui Junjia, Jiang Hao

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e177, 2022

EN

In this paper, the dynamic behavior of clinched, bonded and clinch-bonded joints for steel/Al was investigated. Three tensile speeds (1 m/s, 5 m/s, and 10 m/s) were selected. The strain evolution of three kinds of joints was analyzed by the digital image correlation (DIC) technique. The mechanical properties and failure mechanism of joints were obtained. The result showed that the shear strength and energy absorption of joints were both increased as the tensile speed increased. When the tensile speed increased from 1 to 10 m/s, the peak loads of clinched joints, bonded joints and clinch-bonded joints were increased by 26.7%, 17.5% and 16.3%, respectively. The energy absorption of three kinds of joints were increased by 35.4%, 27.3%, and 29.0%, respectively. Besides, the addition of adhesive effectively improved the shear strength and energy absorption of the joint compared to clinched joints. Specifically, the peak load and energy absorption were increased by nearly three times and thirteen times, respectively. The failure modes of clinched joint ranged from mixed failure to neck failure. While the failure modes of bonded joint were mixed failure at different tensile speeds. For clinch-bonded joint, the failure modes of interlock structure were the neck failure and the failure modes of adhesive layer were mixed failure. With the increase of the tensile speed, the cohesive failure area of bonded joint and clinch-bonded joint decreased, and the damage degree of mechanical interlock was more serious for clinched joint.

9

Experimental study on the mechanical properties of textile reinforced mortar (TRM) composites with different yarn shapes subjected to uniaxial tension

Dong Zhifang, Dai Jie, Deng Mingke, Wu Zhiyan

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e185, 2022

EN

Textile reinforced mortar (TRM) has been applied to retrofit or reinforce the masonry and reinforced concrete (RC) buildings due to the promising tensile properties. The presented work mainly investigated the tensile behaviors of TRM composites with different shapes of carbon multifilament yarns and types of matrices. The flatter shape of yarn has a larger bonding area for the same cross section area of the yarns compared with the elliptical ones. The specimens reinforced with the elliptical and flatter sectional shape of yarns were compared in terms of failure mode, tensile strength, tensile stress–strain response and strain energy. The results showed that the tensile strength can be enhanced by 11% ~ 67%. The utilization of the textiles in the matrix was significantly improved. It demonstrated the fact that the stress difference between the core and outer of yarns was significantly reduced. The flatter shape of yarn effectively contributed to the enhancement of bonding property. The slippage between yarns and matrix was prevented owning to the larger bonding area. Finally, based on the shape coefficient related to the section shape of the yarn, a modified index model was suggested to predict the tensile strength.

10

Experimental investigation of bonding behavior of anchoraged timber-to-timber joint

Ghoroubi Rahim, Mercimek Ömer, Sakin Shaimaa, Anil Özgür

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e7, 2022

EN

The comprehensive experimental study examining the general load–displacement behavior, stress distributions and shear stress–shear-displacement behaviors in the connection area when wood structural elements are combined with adhesive or adhesive with mechanical anchorages have been found in very limited number of studies in the literature. Therefore, an experimental study was planned. In this study, the general load–displacement behavior of the timber connection regions which are connected by adhesive and mechanical anchorages together with adhesive, with varying lengths of 180, 240 and 350 mm are investigated experimentally. Besides, the effect of changing the number and location of mechanical anchorages used in the connection area on the general load–displacement behavior and shear stress–shear-displacement behavior was also investigated. Using the load–displacement graphs obtained as a result of the experimental study, a generalized material model is proposed for the shear stress–shear-displacement interfacial adhesion surface for wood–wood junction points. This material model, which is proposed for wood–wood connection points with mechanical anchors, is a model that can be useful and can be used in the analysis of structural systems containing such connections using finite element software. It is thought that the overall capacity and load–displacement behavior of structural systems containing such connection points can be calculated more realistically using the proposed interfacial material model.

11

Evaluation of a low-cost approach to 2-D digital image correlation vs. a commercial stereo-DIC system in Brazilian testing of soil specimens

Arza-García M., Núňez-Temes C., Lorenzana J. A., Ortiz-Sanz J., Castro A., Portela-Barral M., Gil-Docampo M., Bastos G.

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e4, 2022

EN

Due to their cost, high-end commercial 3D-DIC (digital image correlation) systems are still inaccessible for many laboratories or small factories interested in lab testing materials. These professional systems can provide reliable and rapid full-field measurements that are essential in some laboratory tests with high-strain rate events or high dynamic loading. However, in many stress-controlled experiments, such as the Brazilian tensile strength (BTS) test of compacted soils, samples are usually large and fail within a timeframe of several minutes. In those cases, alternative low-cost methods could be successfully used instead of commercial systems. This paper proposes a methodology to apply 2D-DIC techniques using consumer-grade cameras and the open-source image processing software DICe (Sandia National Lab) for monitoring the standardized BTS test. Unlike most previous studies that theoretically estimate systematic errors or use local measures from strain gauges for accuracy assessment, we propose a contrast methodology with independent full-field measures. The displacement fields obtained with the low-cost system are benchmarked with the professional stereo-DIC system Aramis-3D (GOM GmbH) in four BTS experiments using compacted soil specimens. Both approaches proved to be valid tools for obtaining full-field measurements and showing the sequence of crack initiation, propagation and termination in the BTS, constituting reliable alternatives to traditional strain gauges. Mean deviations obtained between the low-cost 2D-DIC approach and Aramis-3D in measuring in-plane components were 0.08 mm in the perpendicular direction of loading (ΔX) and 0.06 mm in the loading direction (ΔY). The proposed low-cost approach implies considerable savings compared to commercial systems.

12

Effect of single roll drive cross rolling on the microstructure, crystallographic texture, and mechanical behavior of Al–Zn–Mg–Cu alloy

Kazemi-Navaee Amir, Jamaati Roohollah, Aval Hamed Jamshidi

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e41, 2022

EN

In this work, the effect of single roll drive cross rolling on the microstructure, crystallographic texture, hardness, tensile properties, and fracture behavior of AA7075 aluminum alloy was investigated. It was found that with increasing the thickness reduction, the grain size reduced and the average width of grain for the 40% deformed sample decreased to 3.7 ± 0.4 µm. Due to the nature of the cross-rolling process, several X-type shear bands were observed after 40% deformation. The recrystallization texture is notably intensified to its highest value of 4.4 × R, after only 20% cold deformation due to the occurrence of continuous dynamic recrystallization (CDRX). The intensity of recrystallization texture sharply dropped to its lowest value of 2.7 × R. This was due to the rotation of Goss-orientated new grains in the 20% deformed sample toward copper orientation during 40% rolling. With increasing the thickness reduction, the overall texture intensity significantly reduced owing to the nature of the cross-rolling process in which the rolling direction rotates 90° after each 10% strain. Two texture transitions were observed along τ fiber: rolling (copper) texture to recrystallization (Goss) texture after 20% thickness reduction and recrystallization to the rolling texture after 40% deformation. The hardness and strength increased by increasing the thickness reduction, while the ductility decreased. After a 40% thickness reduction, yield strength significantly increased from 138.3 ± 4.4 MPa (for initial sample) to the highest value of 580.5 ± 11.5 MPa, demonstrating 320% increment, in the 0° direction. This increment for 45° and 90° direction was 265% and 337%, respectively. By 40% rolling, the value of in-plane anisotropy (IPA) remarkably decreased to its lowest value of 3.4% due to texture weakening. With increasing the rolling reduction to 20%, the severity of Portevin–Le Chatelier (PLC) increased in the flow curves due to the occurrence of CDRX and also strengthening of the rotated cube {001} < 110 > and E {111} < 110 > components. With increasing the rolling reduction, the size of cleavage facets and the severity of delamination increased, and the number and depth of dimples decreased.

13

Comparative analysis of cold and warm rolling on tensile properties and microstructure of additive manufactured Inconel 718

Zhang Tao, Li Huigui, Gong Hai, Wu Yunxin, Ahmad Abdulrahaman Shuaibu, Chen Xin, Zhang Xiaoyong

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e44, 2022

EN

Despite the high efficiency and low cost of wire + arc additive manufacture (WAAM), the epitaxial grown columnar dendrites of WAAM deposited Inconel 718 cause inferior properties and severe anisotropy compared to the wrought components. Fundamental studies on the influence of one-pass cold and warm rolling on hardness and microstructure were investigated. Then the interpass cold and warm rolling on tensile properties were also analyzed. The results show that the one-pass rolling increases the hardness and displays a heterogeneous hardness distribution compared to the as-deposited material, and the warm rolling exhibits a larger and deeper strain compared to cold rolling. The columnar dendrites gradually change to cell dendrites under the rolling process and then change to equiaxed grains with the subsequent new layer deposition. The average grain size is 16.8 μm and 23.5 μm for the warm and cold rolling, respectively. The strongly textured columnar dendrites with preferred < 001 > orientation transform to equiaxed grains with random orientation after rolling process. The grain refinement contributes to the dispersive distributed strengthening phases and the increase in its fraction with heat treatment. The as-deposited samples show superior tensile properties compared to the cast material but inferior compared to the wrought components, while the warm-rolled samples show superior tensile properties to wrought material. Isotropic tensile properties are obtained in warm rolling compared to cold rolling. The rolling process and heat treatment both decrease the elongation and lead to a transgranular ductile fracture mode. Finally, the rolling-induced strengthening mechanism was discussed.

14

Assessment of Reuss, Tamura, and LRVE models for vibration analysis of functionally graded nanoplates

Shahsavari Davood, Karami Behrouz

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e92, 1--13

EN

Majority of structural analysis on functionally graded materials utilized Voigt and Mori-Tanaka micromechanical modelling. The current article is focused on free vibration response of inhomogeneous nano-size plate resting on elastic foundations against different micromechanical models (i.e., Reuss, Tamura, and LRVE). For the elastic foundation type, Winkler, Pasternak, and Kerr mediums are modelled one by one. The nanoplate is modelled based on a quasi-3D shear deformation plate theory which is in relation with general strain gradient theory by employing Hamilton principle, then the model is solved analytically via Navier solution procedure. This exact model determines fourfold coupled (stretching-axial-bending-shear) response with estimating softening-stiffness and hardening-stiffness mechanisms of nano-sized systems. Finally, numerical results are provided to represent the influence of size-dependent effects on vibrations of embedded nanoplate obtained through different micromechanical models.

15

Influence of untreated abaca fibre on mechanical properties of lightweight foamed concrete

Othuman Mydin Md Azree

Architecture Civil Engineering Environment

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2022

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Vol. 15, no. 3

51--61

EN

Presently, the expenditure on construction materials grows dramatically along with the enduring effect on the ecosystem, and it has led the academics to the recognition of natural plant fibres such as abaca fibre (AF) for enhancing the mechanical properties of concrete. AF is plentifully obtainable making it fairly relevant to be employed as a strengthening material in lightweight foamed concrete (LFC). Moreover, natural plant fibre-reinforced concrete has been progressively utilized in construction for several decades to decrease crack growth under the static load. This paper anticipates examining the effectiveness of the addition of AF in LFC to enhance its mechanical properties. LFC specimens of 550 kg/m3 density were reinforced with AF at weight fractions of 0.00%, 0.15%, 0.30%, 0.45% and 0.60%. Three parameters have been assessed which were flexural strength, compressive strength and tensile strength. The results revealed that adding 0.45% AF into LFC enables optimal compressive, flexural and splitting tensile strengths. The presence of AF augments material strength by filling spaces, micro-cracks, and gaps inside the LFC structure. Additionally, AF helped reduce crack spreading when the plastic state of the LFC cementitious matrix was loaded. Though, further, than the optimum level of AF addition, accumulation and the non-uniform distribution of AF were identified, which triggers the lowering of the LFC strength properties substantially. The output of this preliminary investigation would give a better understanding of the potential utilization of plant fibre in LFC. It is of great importance to drive the sustainable development and application of LFC material and infrastructures.

16

Utilization of wrightia tinctoria nano seed fibers as a reinforcement in the preparation of epoxy-based composites

Syed Habibunnisa, Nerella Ruben, Madduru Sri Rama Chand, Reddy S Raja Gopal

Acta Innovations

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2022

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no. 45

5--17

EN

Natural seed fiber reinforced composite materials are replacing many conventional ones because of their excellent properties, less weight, easy availability, etc. Composite materials are used in many areas because of their superior features. Mechanical property is one of the vital parameters for choosing the material. The current investigation has revealed an importance of recently well-known Wrightia tinctoria nano seed fibers (WTNSFs), which are extracted physically. Wrightia tinctoria nano seed fiber reinforced composite was prepared with the epoxy resin by hand layup method. Epoxy resin is easy to handle and available at low cost. Mechanical tests are conducted reinforced composites of plain epoxy and WTNSFs to obtain strength properties like tensile, flexural, impact. Water absorption tests also performed on composites. Here, the developed composites are easy to handle, offered economically, and used primarily in marine applications due to less water absorption and good wax content. A comprehensive description of different tests and the properties of WTNSFs are studied and compared with the other existing natural fibers. This work showed that 35% combination of WTNSFs reinforced epoxy matrix offers enhanced mechanical properties with minimum water absorption compared with plain epoxy composites.

17

An analysis of innovative and maintenance free active pre-stressed soil nail with reinforced grout hybrid anchor in the region of Rawang, Malaysia

Jamain Mohd Fadhil, Muda Mohammad Ashari, Beddu Salmia, Noor Mohamad Jamaludin Md, Manan Teh Sabariah Binti Abd, Ahmad Mushtaq

Acta Geophysica

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2022

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Vol. 70, no 6

2965--2978

EN

Steep cut slops along the highways and hillsides closer development projects are generally stabilize using soil nailing method in Malaysia. Soil nail system (i.e., passive and active soil nail systems integrated with tendons pre-stressed) is widely applied to strengthened slopes. However, slope failures occurred observing flaws on the fundamental design. The loss of the pre stressed tension on the creep behaviour of the nail tendon affects the functionality of the soil nail system. This research has introduced a cylindrical shape reinforced grout hybrid anchor and the objectives is to assess its efficiency at refraining the creep behaviour of the soil. Therefore, laboratory evaluation of the pull-out creep behaviour of the anchor was assessed in a large pull-out box (length: 2 m, σ: 1 m×1 m). An effective stress of 100 and 200 kPa were applied to the soil in the pull-out box. The creep behaviour was tested at the pull-out tensions of 100 and 200 kN, respectively. Results show that the prestressing force is the main factor affecting the stress and deformation in the soil. The anchor was able to mobilise the tensions of 100 and 200 kN. The load was maintained, and the creep behaviour was monitored. A minimal amount of creep (approximately 1 mm) was observed. This finding presents a good justification showing that, the anchor could resist creep and thus can function as a maintenance free active soil nail system.

18

Wytrzymałość połączenia metal-szkło w szkle laminowanym z folią strukturalną PVB

Louter Christian, Santarsiero Manuel

Świat Szkła

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2021

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R. 26, nr 10

60--65

19

Obróbka cieplno-mechaniczna stopów Mg

Sułkowski Bartosz

Stal, Metale & Nowe Technologie

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2021

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nr 9-10

44--48

PL

Stopy magnezu ze względu na mały ciężar właściwy są stosowane w tych gałęziach przemysłu, w których redukcja masy jest kluczowa. Mowa tutaj o przemyśle samochodowym, lotniczym i kosmicznym. Wadami stopów magnezu są podatność na korozję oraz słabe własności mechaniczne. Wytrzymałość na rozciąganie w stopach magnezu rzadko przekracza 300 MPa i bardzo szybko maleje wraz ze wzrostem temperatury.

EN

Due to their low specific weight, magnesium alloys are used in industries where weight reduction is crucial. We are talking about the automotive, aerospace and aerospace industries. The disadvantages of magnesium alloys are susceptibility to corrosion and poor mechanical properties. The tensile strength in magnesium alloys rarely exceeds 300 MPa and decreases very quickly as the temperature increases.

20

Effects of pressure gradient on convective heat transfer in a boundary layer flow of a Maxwell fluid past a stretching sheet

Kashif A. N., Salah F., Sankar D. S., Izyan M. D. N., Viswanathan K. K.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 3

104--118

EN

The pressure gradient term plays a vital role in convective heat transfer in the boundary layer flow of a Maxwell fluid over a stretching sheet. The importance of the effects of the term can be monitored by developing Maxwell’s equation of momentum and energy with the pressure gradient term. To achieve this goal, an approximation technique, i.e. Homotopy Perturbation Method (HPM) is employed with an application of algorithms of Adams Method (AM) and Gear Method (GM). With this approximation method we can study the effects of the pressure gradient [...], Deborah number [...], the ratio of the free stream velocity parameter to the stretching sheet parameter [...] and Prandtl number [...] on both the momentum and thermal boundary layer thicknesses. The results have been compared in the absence and presence of the pressure gradient term m. It has an impact of thinning of the momentum and boundary layer thickness for non-zero values of the pressure gradient. The convergence of the system has been taken into account for the stretching sheet parameter. The result of the system indicates the significant thinning of the momentum and thermal boundary layer thickness in velocity and temperature profiles.