Tensile Rupture Strength Research Articles

Degradation Behavior and Mechanical Properties of Porous Biodegradable FeMnC Alloys Produced by Powder Metallurgy for Biomedical Applications

The advent of biodegradable implants represents a landmark orientation in the biomedical field toward a new generation of medical devices, offering improved patient outcomes, and eliminating the need for subsequent surgeries. FeMn alloys are well‐established as promising candidates for such applications. This study analyzes the microstructure, mechanical properties, and degradation behavior of FeMnC alloys produced via pressing and sintering process using water‐atomized FeMnC powder. To investigate the impact of pore size and volume fraction on the mechanical properties and degradation rates, two groups of FeMnC samples were prepared, one compacted at 600 MPa (CP 600) and the other at 700 MPa (CP 700). In addition, pure Fe samples compacted at 600 MPa and prepared using the same methodology were used as a reference. Chemical analysis carried out on both the pre‐alloyed powder and the resulting sintered samples (CP 600 and CP 700) revealed a significant reduction in the amount of Mn, O, and notably C after sintering. The pure Fe group showed the greatest mechanical strength with an average tensile rupture strength of 446 ± 24 MPa. Among the three groups, CP 600 exhibited the highest degradation rate (−0.339 ± 0.057 mmpy) after 14 days of static immersion degradation test in modified Hanks' solution, demonstrating a degradation behavior characterized by mass gain.

Influence of Bolt Threads on the Net Section Tensile Rupture Strength of Single-Bolt Connections in Pultruded Structures

Influence of Bolt Threads on the Net Section Tensile Rupture Strength of Single-Bolt Connections in Pultruded Structures

Effect of nano-silica on the flexural behavior and mechanical properties of self-compacted high-performance concrete (SCHPC) produced by cement CEM II/A-P (experimental and numerical study)

The extensive use of cement exacerbates the greenhouse effect by increasing carbon dioxide (CO2) emissions. So, many standards recommend using Portland-composite cement in construction as one of the methods for reducing CO2 emissions, especially cement CEM II/A-P. This paper presents an extensive experimental and numerical study to investigate the effect of micro and nano-silica on the flexural behavior and mechanical properties of Self-Compacted High-Performance Concrete (SCHPC) produced by cement CEM II/A-P. The extensive experimental work consisted of eight mixtures: three with micro-silica (MS), four with nano-silica (NS), and a reference mixture without silica. For both MS and NS, different percentages of adding or replacement content were tested to study their effect on the following: (a) the workability of fresh concrete, (b) concrete compressive strength, (c) splitting tensile strength, (d) flexural behavior including flexural tensile strength, and (e) the optimum percentage of each of the MS and NS to get the maximum structural and economic benefits of using for SCHPC with CEM II/A-P. Also, through a statistical program, these experimental results were used to obtain accurate formulae that could predict both the splitting tensile strength (fsp) and modulus of rupture (fctr) for SCHPC with adding nano-silica. In addition, the numerical study verified the experimental results based on the finite element program ANSYS. The flexure behavior of SCHPC beams is verified using the Microplane model (recently added to ANSYS). The experimental results showed that adding NS is more effective than replacing or adding MS for SCHPC mixture with CEM II/A-P to increase the concrete compressive strength, splitting tensile strength, and flexural tensile strength, especially for the mixture with adding NS content of 4 %. The numerical results showed the ability of the coupled damage-plasticity microplane model to simulate the flexural behavior of the tested SCHPC beams with MS or NS well. This research confirms nano-silica's structural and economical efficiency in the behavior of SCHPC beams. It was found that the optimum percentage of adding NS is 4 % for SCHPC mixtures with CEM II/A-P.

Effect of High-Density Packing Recycled Aggregate on Concrete Strength Properties

As many residential homes and structures were destroyed or badly damaged because of the military battle in Iraq, it is critical to recycle construction debris widely in the rebuilding and decoration of buildings and infrastructure. This battle resulted in the buildup of massive construction debris, and recycling this waste allows for a cleaner environment. Recycling the construction waste of various installations is an urgent need to decrease the consumption of natural materials and landfills of construction waste, and as a result reduce the environmental pollution. Therefore, this study is a local focus on using concrete debris to obtain high packing density recycled coarse and fine aggregates in various fractions of (0.16 mm - 10 mm) by selecting high-density packing materials that was developed by Kharkhadin A.N in laboratories of Belgorod State Technical University in Russia to preparing of reference mix from ordinary density recycled aggregate. The new concrete samples for two concrete mixtures were prepared, to identify and study the important specifications. Models of cubes and standard prisms were prepared to evaluate the compressive strength and the splitting tensile strength. Also, the modulus of rupture and the unit weight were conducted. The results indicated an increase in the concrete’s mechanical properties using the high-packing density recycled aggregate. The obtained compressive strength, splitting tensile strength and modulus of rupture were (49) MPa, (3.6) MPa, and (7.1) MPa compared with a reference mix (39) MPa, (3.3) MPa and (6.3) MPa, respectively. The reference mix corresponding properties were (39) MPa, (3.3) MPa, and (6.3) MPa, respectively. Also the values of an oven-dry density were (2340) kg/m3 compared with the reference mix (2260kg/m³). These results proved that increasing the packing density of recycled aggregate enhanced the concrete’s strength properties.

Hydrostatic pressure under hypoxia facilitates fabrication of tissue-engineered vascular grafts derived from human vascular smooth muscle cells in vitro.

Biologically compatible vascular grafts are urgently required. The scaffoldless multi-layered vascular wall is considered to offer theoretical advantages, such as facilitating cells to form cell-cell and cell-matrix junctions and natural extracellular matrix networks. Simple methods are desired for fabricating physiological scaffoldless tissue-engineered vascular grafts. Here, we showed that periodic hydrostatic pressurization under hypoxia (HP/HYP) facilitated the fabrication of multi-layered tunica media entirely from human vascular smooth muscle cells. Compared with normoxic atmospheric pressure, HP/HYP increased expression of N-myc downstream-regulated 1 (NDRG1) and the collagen-cross-linking enzyme lysyl oxidase in human umbilical artery smooth muscle cells. HP/HYP increased N-cadherin-mediated cell-cell adhesion via NDRG1, cell-matrix interaction (i.e., clustering of integrin α5β1 and fibronectin), and collagen fibrils. We then fabricated vascular grafts using HP/HYP during repeated cell seeding and obtained 10-layered smooth muscle grafts with tensile rupture strength of 0.218 to 0.396 MPa within 5 weeks. Implanted grafts into the rat aorta were endothelialized after 1 week and patent after 5 months, at which time most implanted cells had been replaced by recipient-derived cells. These results suggest that HP/HYP enables fabrication of scaffoldless human vascular mimetics that have a spatial arrangement of cells and matrices, providing potential clinical applications for cardiovascular diseases. STATEMENT OF SIGNIFICANCE: : Tissue-engineered vascular grafts (TEVGs) are theoretically more biocompatible than prosthetic materials in terms of mechanical properties and recipient cell-mediated tissue reconstruction. Although some promising results have been shown, TEVG fabrication processes are complex, and the ideal method is still desired. We focused on the environment in which the vessels develop in utero and found that mechanical loading combined with hypoxia facilitated formation of cell-cell and cell-matrix junctions and natural extracellular matrix networks in vitro, which resulted in the fabrication of multi-layered tunica media entirely from human umbilical artery smooth muscle cells. These scaffoldless TEVGs, produced using a simple process, were implantable and have potential clinical applications for cardiovascular diseases.

Mechanical and GWP assessment of concrete using Blast Furnace Slag, Silica Fume and recycled aggregate

Demolition waste and cement production is responsible for 36 % of total waste produced on earth and 8 % of the worlds CO2 emissions, respectively. Due to limited research on concrete mixes containing ternary cementitious mixes (Ground Granulated Blast-furnace Slag (GGBS) and Silica Fume (SF)) and demolition waste, the paper reviewed the mechanical properties of concrete, and structural performance of reinforced beams. Thereafter, life cycle analysis (LCA) was investigated to understand the true environmental impact, focusing on Global Warming Potential (GWP). Results show that recycled concrete aggregates (RCA) had no significant negative impact on the compressive strength, tensile strength, and modulus of rupture of concrete. The inclusion of GGBS and SF in mixes containing RCA eliminated any negative impact and for all mixes produced greater strengths in comparison to the control mix, due to the secondary reaction of Ca (OH)2 and pore refinement. The flexural behaviour of the concrete beams with 0 %, 25 %, 50 % and 100 % RCA, 25 % GGBS and 5 % SF is similar. LCA results showed that replacing NA with 25 %, 50 % or 100 % RCA has no significant impact on the GWP emissions. This is because of the similar emissions associated with manufacturing and processing of recycled and natural aggregates. However, replacing cement with 5 % SF and 25 % GGBS improves the GWP environmental response of concrete significantly. Additionally, natural aggregates have a higher GWP contribution than that of recycled concrete aggregates by almost 80 % since the process of NA required quarry operation and transportation while the RCA are produced on site from an existing building waste.

Erratum for “Revisiting the Net-Section Tensile Rupture Strength Limit State of Single-Bolt Connections in Pultruded Structures” by Abdul-Hamid Zureick and Blaine Weinmann

Erratum for “Revisiting the Net-Section Tensile Rupture Strength Limit State of Single-Bolt Connections in Pultruded Structures” by Abdul-Hamid Zureick and Blaine Weinmann

Experimental study of the torsional effect for yarn break load test of polymeric multifilaments

Polymeric multifilaments have gained a significant interest in recent decades. In the studies of mechanical characteristics, although there are different types of tests, such as rupture, abrasion, creep, impact and fatigue, it can be said that the main mechanical characterisation is the tensile rupture strength (Yarn Break Load, YBL), which also serves as a parameter for other tests. The objective of this work is to evaluate the results of breaking strength under different torsional conditions in polymeric multifilaments and to determine optimal twists for failures. The test were carried out with the following materials: polyamide, polyester, and high modulus polyethylene (HMPE), and for torsional conditions: 0, 20, 40, 60, 120, 240, and 480 turns per metre. As a result, for these torsion groups, curves were obtained for the three materials that present an optimal point of maximum rupture value, which was also experimentally proven. The twist that optimises the breaking strength of HMPE is 38 turns per metre, 56 turns per metre for polyester, and 95 turns per metre for polyamide. The twist groups that exceed the optimal torsion have a deleterious effect on the material, where the multifilament ceases to be homogeneous and starts to create an excessive "spring effect". The results found differ from the recommendation of the standard that regulates the YBL test, and thus, a relationship is built between groups of optimal torsion and linear density that provides evidence that the increase in linear density causes the optimal torsion for rupture to also increase, while the standard places a condition of 30 turns per metre for linear densities greater than 2200 dtex, and 60 turns per metre for linear densities less than 2200 dtex. In addition to optimal torsion values, this conclusion is paramount, the test procedure makes a general recommendation that does not optimise the breaking strength.

Design and development of an environmentally controlled enclosure for a commercial 3D printer

PurposeThe purpose of this study is to design and develop an environmentally controlled enclosure for commercial three-dimensional (3D) printers.Design/methodology/approachComputational fluid dynamics (CFD) simulations and experimental testing investigated various designs for environmentally controlled enclosures. CFD simulations provided the necessary information to select the optimal and feasible design, whereas experimental testing validated the CFD simulation results. An environmentally controlled environment allowed test samples to be printed at several relative humidity (RH) settings (20% RH, 50% RH and 80% RH). The test samples were characterized at both the macro and micro scales. The macroscale characterization was conducted using the static tensile testing procedure, while the microscale polymer material properties were determined using atomic force microscopy.FindingsAn environmentally controlled enclosure was designed and built to produce airflow in the print region with an average RH uniformity of over 0.70. Three batches of ASTM D638 standard test samples were printed at 20% RH (low RH), 50% RH (mid RH) and 80% RH (high RH). Macroscale characterization showed that the samples printed at lower humidity had statistically significantly higher tangent modulus, ultimate tensile strength and rupture strength. atomic force microscopy studies have also verified these results at the microscale and nanoscale. These studies also showed that a high humidity environment interacts with melted polylactic acid, causing additional surface roughness that reduces the strength of 3D-printed parts.Originality/valueThere is a need for stronger and higher-quality 3D-printed parts in the additive manufacturing (AM) market. This study fulfills that need by designing and developing an environmentally controlled add-on enclosure for the AM market.

Experimental Investigation of Recycled Fine Aggregate from Demolition Waste in Concrete

In this study, locally produced recycled fine aggregate from concrete demolition waste was investigated for potential replacement of sand in new concrete mixes. Tests for the waste material included visual examination, chemical composition, grain size distribution, specific gravity, and fineness modulus. Tests on the incorporated recycled fine aggregate in new concrete mixes involved tests of the hardened plain concrete product. In total, eight concrete mixes were considered, of which four had low cement content with 30 MPa target strength, and the other four had high cement content with 55 MPa target strength. For each cement content, the four concrete mixes incorporated fine aggregate replacement ratios of 0% (control), 25%, 50%, and 100%. The hardened concrete tests involved cubes, cylinders, and prisms. The tests addressed compressive strength, tensile strength, and modulus of rupture in accordance with the relevant ASTM standards. In all cases, the average of two tested samples at the age of 28 days was considered. Results of the study showed that the recycled fine aggregate has some cementitious properties, which is capable of hardening when mixed with water and left to dry, even without adding cement from exterior sources. All tested concrete specimens made with recycled fine aggregate exhibited compressive and tensile strengths at least equal to 75% that of the control specimens that contained natural fine aggregate. However, for concrete mixes utilizing low cement content that can yield a compressive strength around 30 MPa with natural aggregate, replacement of 25% or 100% of the natural fine aggregate by weight with locally produced recycled fine aggregate from crushed old concrete can match and often exceeds the compressive and tensile strength of concrete made with virgin aggregate.

The Influence of Location along the Pseudostem on Enset Fiber Physio-Mechanical Properties: Application of Weibull Distribution Statistics

Enset bundle fibers were divided lengthwise into four sections from bottom to top and the sections’ physio-mechanical parameters were studied and compared. The four equal fiber sections from the bottom were 0–375 mm (EV-I), 375–750 mm (EV-II), 750 mm–1125 mm (EV-III), and 1125–1500 mm (EV-IV). The mass distribution, cross-sectional area, linear density, and diameter all decreased along the fiber sections from bottom to top. The CIE Lab-color values of each fiber section were also examined, and the L* value for EV-II fiber section was higher. In terms of mechanical properties, the Enset bundle fiber’s tensile strength and work of rupture were analyzed, and both increased by 25% from the lower fiber section to the second fiber section (EV-1 to EV-II) along the length before decreasing significantly at the top sections. The investigation indicated that a higher Weibull modulus and tensile strength characteristics for EV-II were recorded while a low Weibull modulus and low strength characteristics of the Enset bundle fiber section EV-IV were observed. The investigation of Weibull distribution variability in the EV-IV fiber location was also confirmed using one-way ANOVA. Overall, the present study investigates the impact of fiber position along the plant stem on the mechanical and physical properties of Enset bundle fibers which can be used as an input for the optimization of unidirectional composites.

Dual-network self-healing hydrogels composed of graphene oxide@nanocellulose and poly(AAm-co-AAc)

A nature-inspired strategy is developed to build dual-network hydrogels made up of rigid graphene oxide-functionalized nanocellulose (GO@NC) network and flexible poly[acrylamide-co-(acrylic acid)] (poly(AAm-co-AAc)) network. A pre-stretching method is used to form a muscle-shape anisotropic architecture. The penetration of poly(AAm-co-AAc) flexible network relieves the stiffness of NC network, thus improving the average elongation at break from 86.2 % to 748.0 %. Compared with the poly(AAm-co-AAc), the average rupture tensile strength rises remarkably by 228.6 %. The dual-crosslinked strategy endows the GO@NC-poly(AAm-co-AAc) hydrogels with a fast, stable and repeatable self-healing ability, which can achieve 85.0 % of healing efficiency after only 600 s of self-healing and maintain 76.2 % of initial strength after 10 cycles of breaking–self-healing. The superb self-healing ability is similar to the muscle function. For potential applications, the hydrogels can achieve real-time, stable, and long-term sensing as smart wearable strain sensors (high gauge factor: 5.13), and can effectively purify Sudan IV wastewater as green recyclable adsorbents.

The combined effect of steel fibres and high-range carbon nanotubes on properties of high-strength concrete

The present study investigated the effect of the addition of steel fibres (SFs) and the synergy of SFs and carbon nanotubes (CNTs) on the mechanical properties of high-strength concrete (HSC). The addition of CNTs prevents the growth of micro cracks during loading, creates a denser composite and enhances the bond between SFs and cement paste. Three samples of HSC with a compressive strength of 68 MPa as a control sample, HSC with 1% volume fraction of SFs (HSC + SF1), HSC with 1% volume fraction of SFs and 0.8% cement weight of CNTs (HSC + SF1 + CNT) were prepared. The mechanical properties of samples including compressive strength, tensile strength, modulus of rupture, stress–strain curves and water absorption were investigated. The CNTs were mixed using an ultrasonic device in superplasticiser and water for 50 min to disperse homogenously. The results showed that adding 1% SFs to concrete improved the properties of concrete. The combined usage of SFs and CNTs in concrete increased the compressive strength, tensile strength and modulus of rupture up to 13.1, 39.7 and 49.3%, respectively, compared to HSC, and 6, 12 and 14.6%, respectively, compared to HSC + SF1. Furthermore, the combined use of steel fibres and CNTs improved the toughness of HSC by 35% compared to HSC + SF1 and reduced water absorption of HSC by about 15%.

Mechanical response to axial strain in WS2 nanotubes

In order to take advantage of inorganic nanotubes for their use with pragmatic purposes, characterization of their mechanical properties becomes a relevant issue. In the present study, a series of results on the mechanical properties of WS2 nanotubes of several diameters and two main lattice orientations was obtained by the implementation of molecular dynamics simulations using an interatomic potential of the Stillinger-Weber kind. A Young's modulus for nanotubes of H polytype close to 170 ​GPa was obtained in accordance with experimental results, and of ≈ 130 ​GPa for nanotubes of the T polytype, with almost no dependance on the diameter of the nanotube. The tensile strength was as large as 20 ​GPa ​(H armchair nanotubes, close to the value obtained in experiments), and the strain at the point of rupture reached values close to 0.24. The effect of several kinds of defects on the mechanical properties was investigated, and the results showed that when the defects consisted in the absence of a whole WS2 unit, the tensile strength and point of rupture dropped considerably, and the fracture became more brittle than in pristine nanotubes. The dependence of the mechanical properties on temperature was also investigated.

Mathematical Models for Tensile Resistance Capacities of Concrete

Although the uniaxial tensile strength (ft) of concrete is one of the most essential properties in designing and analyzing the tensile performance of a concrete member, a rational consensus to assess it is still lacking because of experimental difficulties. The objective of the present study is to generalize ft through mathematical analysis based on the plasticity of concrete. The principle of equivalent resultant tensile forces at failure planes is introduced to straightforwardly determine the splitting tensile strength (fsp) and modulus of rupture (fr) from ft. The accuracy and reliability of the proposed equations are confirmed at different ranges of the compressive strength and unit weight of concrete by comparing with test data, including 219, 674, and 242 data sets for uniaxial tension tests, splitting tension tests, and flexural tests, respectively. Thus, the present mathematical approaches proved the significance of considering the concrete unit weight and maximum aggregate size in predicting the tensile resistance capacities of the concrete. However, with the variations of the compressive strength and unit weight of concrete, the empirical equations recommended in previous studies and code provisions are insufficient.

Concrete Properties using Treated Recycled EPS

The study explores the mechanical properties of treated recycled extended polystyrene (TEPS) concrete, treated by two methods, one by heating, and the other by immersed recycled EPS in cement neat. By substituting 0 %, 15 %, 25 %, and 35 % of the coarse aggregate volume with treated recycled EPS, (for both method). Treated recycled TEPS concrete ratios are experimentally prepared, while the cement is substituted thru 10 % silica fume (SF). Tests were carried out, like compressive strength, splitting tensile strength, modulus of rupture, and density. The outcomes display the decreasing of the compressive strength, tensile strength and modulus of rupture of TEPS concretes with rise TEPS percentage around 26 %, 17 % and 32 %, respectively (35% TEPS) related to standard concrete. They also show that TEPS concrete density decrease about 30 % of normal concrete. The TEPS is suitable in concrete and meets provisions.

Mechanical Properties of Barchip Polypropylene Fibre-reinforced Lightweight Concrete Made With Recycled Crushed Lightweight Expanded Clay Aggregate

Concrete is one of the broadly used construction materials in the construction industry. This research intends to recommend the replacement of conventional coarse aggregates with recycled lightweight expanded clay aggregate (LECA) which offers several advantages such as lightweight, low cost, and easy availability. Lightweight concrete (LWC) offers numerous benefits; therefore, many researchers are using lightweight aggregate to produce lightweight structural composites concrete to compensate heavy loads by reducing the concrete self-weight due to lower density of lightweight concrete, improving in thermal properties and fire resistance, saving the cost of transportation and handling of precast units in the site. Different percentages (0, 0.15, 0.30, and 0.45%) of volume fraction of barchip polypropylene (BPP) fibre have been incorporated to improve the mechanical properties of lightweight aggregate concrete (LWA) concrete. In this study, the mixture of crushed lightweight expanded clay aggregate (CLECA) and barchip polypropylene (BPP) fibre have been used to achieve compressive strength between 28 and 37 MPa at 28-days with an oven-dry density ranged between 1900 and 2000 kg/m3. It is found that the inclusion of BPP fibres at an optimum volume fraction concrete enhances the compressive strength, splitting tensile strength and modulus of rupture. The compressive strength of the lightweight aggregate concrete containing 0.45% volume fraction of BPP fibre (CLLWAC-BPP0.45%) had achieved the highest compressive strength of 37 MPa at 28-days with a significant increment of about 31% compared to plain concrete. Hence, the findings of this research showed that the development of eco-friendly lightweight structural composites can be used as an alternative solution for conventional lightweight concrete, infrastructure and marine fields application.

Analysis of the Shear Lag Factor for Slotted Rectangular HSS Members

Rectangular HSS tension members are often connected by slotting two opposite walls and welding the slotted walls to a gusset plate. Due to a nonuniform stress distribution in these connections, the tensile rupture strength of the member is dependent on a shear lag factor. The accuracy of the 2016 AISC Specification provisions for the tensile rupture strength of slotted HSS tension members was evaluated using existing data from five previous research projects. The results revealed that the current equations are excessively conservative. The accuracy can be improved by replacing the existing equation for the connection eccentricity with the equation proposed in this paper.

Scaffold-free tissue-engineered arterial grafts derived from human skeletal myoblasts.

Tissue-engineered vascular grafts (TEVGs) are in urgent demand for both adult and pediatric patients. Although several approaches have utilized vascular smooth muscle cells (SMCs) and endothelial cells as cell sources for TEVGs, these cell sources have a limited proliferative capacity that results in an inability to reconstitute neotissues. Skeletal myoblasts are attractive cell sources as they possess high proliferative capacity, and they are already being tested in clinical trials for patients with ischemic cardiomyopathy. Our previous study demonstrated that periodic hydrostatic pressurization (PHP) promoted fibronectin fibrillogenesis in vascular SMCs, and that PHP-induced extracellular matrix (ECM) arrangements enabled the fabrication of implantable arterial grafts derived from SMCs without using a scaffold material. We assessed the molecular response of human skeletal myoblasts to PHP exposure, and aimed to fabricate arterial grafts from the myoblasts by exposure to PHP. To examine the PHP-response genes, human skeletal myoblasts were subjected to bulk RNA-sequencing after PHP exposure. Gene-set enrichment analysis revealed significant positive correlations between PHP exposure and vascular development-related genes. Real-time polymerase chain reaction (RT-PCR) demonstrated that PHP significantly upregulated collagen and elastic fiber formation-related gene expression, such as fibronectin, lysyl oxidase, collagen type I α1, collagen type IV α1, and tropoelastin. Based on these findings showing the potential role of PHP in vessel formation, we fabricated arterial grafts by repeated cell seeding and exposure to PHP every 24hours. The resultant 15-layered myoblast grafts had high collagen content, which provided a tensile rupture strength of 899±104mmHg. Human skeletal myoblast grafts were implanted as patch grafts in the aorta of immunosuppressed rats and found to be endothelialized and completely patent until the endpoint of 60 postoperative days. Implanted human myoblasts were gradually replaced by host-derived cells, which successfully formed vascular neotissues with layered elastic fibers. These findings suggest that human skeletal myoblasts have the potential to be a feasible cell source for scaffold-free implantable arterial grafts under PHP culture conditions.

Mechanical properties of MoS2 nanotubes under tension: a molecular dynamics study

ABSTRACT We investigate the tensile properties of MoS nanotubes by the implementation of a set of molecular dynamics runs, using a recently developed version of the Stillinger–Weber (SW) potential. The nanotubes considered are of the H and T polytypes, with zigzag and armchair chirality. We found that only nanotubes of diameter greater or equal than 30 Å are stable when modelled by the SW potential. Zigzag nanotubes have a larger elastic modulus than armchair nanotubes of the same polytype and diameter, and T nanotubes deform more easily than H nanotubes. We also found that elastic modulus, tensile strength, and point of rupture depend on diameter when the diameters are less than 60 Å. We investigate the role of defects on the mechanical response, finding that, while elastic modules is not appreciably affected by the presence of vacancies, tensile strength, and point of rupture value decrease significantly, in particular when the defect is a vacancy of a whole MoS unit. The presence of a defect also affects the nature of the rupture, with the fracture becoming brittle. Increasing the temperature makes Young's modulus and tensile strength decrease. The mechanical response of chiral nanotubes is also investigated.