Tensile Testing Device Research Articles

A method to characterize asymmetrical three-stage creep of ordinary refractory ceramics and its application for numerical modelling

During operation, thermomechanical stresses occur in refractory linings. Under elevated stress and temperatures, these ceramics experience primary creep, which can further proceed to the secondary and tertiary creep stages. This necessitates a characterization of their three-stage creep behavior. Hence, two advanced uniaxial tensile and compressive creep testing devices are utilized. The Norton-Bailey creep equations and an inverse identification procedure are applied for the evaluation of the creep curves. To account for the full three-stage creep behavior in thermomechanical modelling activities, a creep-stage transition criterion is identified and subsequently implemented together with the Norton-Bailey creep-strain rate representations in a new developed creep model. The finite element simulation results from different creep testing procedures are in accordance with the corresponding experimental results of a magnesia-chromite refractory ceramic. The study also reveals the temperature-dependent asymmetrical creep behavior of the material in terms of the creep-strain rates and critical creep strains.

Dorsiflexion and Plantarflexion Test and Analysis for a new Carbon Fiber Ankle-Foot Prosthesis

Dorsiflexion and plantarflexion are an important dynamic function by which the ankle-foot prosthesis must simulate the human foot. Dorsiflexion and plantarflexion are essential functions to the walking pattern. However, most ankle-feet prostheses have a notice lack in mimicking the normal gait dorsiflexion and plantarflexion functions. A new carbon fiber ankle-foot prosthesis has been designed and manufactured. Dorsiflexion and plantarflexion tests achieved using a 25 KN tensile test device. The tests have been simulated and analyzed using ANSYS l6 and the results compared with the experimental results. Both test approaches pointed that the new prosthesis satisfy the ISO 10328 requirements that can be classified as multiaxial as it flexed 10oand 8oin dorsiflexion and plantarflexion respectively, under testing loading less than 1230 N.

Study of tensile properties of multiwalled carbon nanotube/polyether ether ketone polymer composites at the nanoscale

This study demonstrates the microscale and nanoscale mechanical properties of a multiwalled carbon nanotubes/polyether ether ketone (MWCNTs/PEEK) composite utilizing a novel in situ testing method. Nanoscale testing specimens of a composite of PEEK thin film dispersed with 6.5 wt% MWCNTs were successfully prepared using focused ion beam (FIB) and investigated by a tensile testing device accommodated inside a field emission scanning electron microscope. The average tensile strength of the nanocomposite was measured to be 388.66 MPa. The average Young's modulus measured at 6.52 GPa demonstrated a 23% increase compared to that of the bulk specimen, suggesting a size‐dependent mechanism that limits the plastic deformation of the microscale specimens possibly due to the limited defects distribution and motion constraint of the polymer chain in the small specimen and the amorphous regions of the PEEK matrix. POLYM. ENG. SCI., 59:1209–1214 2019. © 2019 Society of Plastics Engineers

Design of a biaxial tensile testing device and cruciform specimens for large plastic deformation in the central zone

A critical issue in biaxial tensile tests is that the central area of the cruciform specimen does not deform to a desired level when the specimen has fractured in other areas. Contrary to the central area thickness reduction approach adopted by the bulk of researchers, this study introduces a thickness-increased sandwich specimen for large strains in the central zone to evaluate the formability and hardening behaviors of sheet metals under complex forming situations. The initial cruciform specimen is strengthened outside the central area by attaching a metal plate in similar shape to each side. This novel specimen has the ability to avoid the inherent characteristics of materials being altered in a thickness-reduced specimen during the material-removing process; moreover, it is applicable to thin sheet metals. Finite element simulations are used for parameter optimization. The optimum set of three key parameters: fillet (R) between the arms, radius (r) of the central zone, and line angle between the notch edge and the horizontal axis (θ), appear to be R = 5.0 mm, r = 4.0 mm, and θ = 21°. The optimized design is corroborated using a new testing device with better synchronization on which various displacement ratios of 1:0 and 0:1 can be implemented by applying 90° wedges so that plane strain conditions in the central zone can be achieved. A maximum equivalent plastic strain of approximately 15% is achieved in the central zone, indicating the effectiveness of the strengthened specimen in increasing the plastic deformation in the desired zone.

Loading frequency improvement in fatigue test of single crystal silicon using parallel tensile testing device

Loading frequency improvement in fatigue test of single crystal silicon using parallel tensile testing device

Performance and testing of adhesive bandage tape

The adhesive plaster or bandage is used to cover non-serious wound or cut in the skin. It is formed by a basic layer of plain fabric coated with the adhesive material. There are several factors that affect the performance of the produced adhesive bandage. One of the frequent reported problems is the strong engagement with the skin that causes severe pain to the patient when it is removed from the skin. The peel test is used to determine the force required to remove the bandage from the skin, tissue or other adhesive tape. The aim of research is to study the factors that affect the performance of adhesive bandage—starting from the raw fabric used and some of the manufacturing machine settings (speed, slit knife height). An attachment was made to test the peeling force of adhesive tape on an ordinary tensile testing device. Results show that the storage of the adhesive bandage tape is the most significant factor that affects the mechanical properties of the adhesive tape.

RANCANG BANGUN ALAT UJI TARIK SERAT ALAM UNTUK MENDUKUNG INDUSTRI NASIONAL

Currently the development trend of composite materials shifts to the reuse of natural fiber (back to nature) as a substitute for synthetic fibers. Measurement of the mechanical properties of fiber (reinforcement) plays an important role in quality control. One of the most important mechanical properties of fiber is its tensile strength. Tensile strength of fiber can be known through tensile test (tensile test). To do tensile test (tensile test) fiber required tensile test machine (tensile test machine). The tensile test equipment used today is a foreign-made commercial tensile test device imported at an exorbitant price. These conditions cause obstacles in the development of basic industries and natural fiber technology. Most laboratories in higher education institutions and other technology research institutions do not have tensile test equipment support. The purpose of this research is to design a natural fiber tensile test apparats which is cheap and easy to operate. The research method using design tool design (design and manufacture). The result of this research is prototype of natural fiber tensile test which has been successfully tested with technical data: 5N loading capacity, calibration curve accuracy: N = 1.052 V and loading rate 0.014 N/s. The result of tensile test to one natural fiber that used abaca fiber obtained the value of tensile strength of an average of 579,90 MPa. The result of tensile test obtained is comparable with the data of tensile test results in existing literatures then there is conformity with the value of tensile strenght. The results of this study are expected to provide benefits for researchers, academics and industry in supporting the development of national natural fiber industry to increase the competitiveness of industries at the international level.

Uniaxial Tensile Testing Device for Measuring Mechanical Properties of Biological Tissue with Stress-Relaxation Test under a Confocal Microscope

Biological soft tissue is a non-linear and viscoelastic material and its mechanical properties can greatly affect quality of life. Many external mechanical factors can alter the tissue, for example the tissue of talipes equinovarus congenitus, also known as clubfoot, which is the most frequent congenital deformity affecting lower extremities with pathological changes of connective tissue. In clubfoot, the presence of disc-like mass of fibrous tissue, resembling intervertebral disc tissue, is described to be between the medial malleolus and the medial side of the navicular bone. The clubfoot tissue is often referred to be stiffer or rigid by clinicians, or it is referred to as contracted and less contracted tissue, however relevant evidence about mechanical properties is missing. Therefore, the description "disc-like" is informing only about relative mechanical properties of clubfoot tissue. We aim to prepare methodical approach to quantify mechanical properties of biological tissue with uniaxial tensile stress-relaxation test, in order to help clinicians and scientist to identify precisely the mechanical properties of normal and pathological tissue and their structural behaviour during mechanical testing. In this study, we test and tune the uniaxial tensile stress-relaxation test on biological tissue with high content of connective tissue such as collagen. The model tissue is porcine pericardium. The tissue has clear collagen fibres aligning parallel to the force applied. Modulus of elasticity measured here is comparable to other studies.

Identification of regional/layer differences in failure properties and thickness as important biomechanical factors responsible for the initiation of aortic dissections

Thoracic aortic dissections involving the ascending aorta represent one of the most dramatic and lethal emergencies in cardiovascular surgery. It is therefore critical to identify the mechanisms driving them and biomechanical analyses hold great clinical promise, since rupture/dissection occur when aortic wall strength is unable to withstand hemodynamic stresses. Although several studies have been done on the biomechanical properties of thoracic aortic aneurysms, few data are available about thoracic aortic dissections. Detailed mechanical tests with measurement of tissue thickness and failure properties were performed with a tensile-testing device on 445 standardized specimens, corresponding to 19 measurement sites per inner (intima with most of media)/outer layer (leftover media with adventitia); harvested from twelve patients undergoing emergent surgical repair for type A dissection. Our data suggested inherent differences in tissue properties between the origin of dissection and distal locations, i.e. thinner and stiffer inner layers that might render them more vulnerable to tearing despite their increased strength. The strength of tissue circumferentially was greater than that longitudinally, likely determining the direction of tear. The relative strengths of the inner: ∼{65,40}N/cm2 and outer layer: ∼{350,270}N/cm2 in the two principal directions of dissected tissue were differentiated from the intima: ∼{100,75}N/cm2, media: ∼{150,55}N/cm2, and adventitia: ∼{270,190}N/cm2 of non-dissected ascending aortic aneurysms (Sokolis et al., 2012), in favor of weaker inner and stronger outer layers, allowing an explanation as to why the presently-studied tissue suffered dissection, i.e. tear of the inner layers, and not rupture, i.e. full tearing across the entire wall thickness.

Influence of microfibers length on PDLA/cellulose microfibers biocomposites crystallinity and properties

Numerous researches have paid attention to biocomposites. Biocomposite material can be defined as a composite material obtained by products derived from renewable resources such as polylactide acid. The aim of this work was to study biodegradable composites prepared by using cellulose microfibrils (CMFs) as the reinforcement and poly (d-lactic) acid as a matrix. Five average fiber lengths, from 8 to 300 μm, were used for the biocomposite preparation. The thermomechanical properties, crystallization, and the composites morphology were characterized by the means of dynamic mechanical thermal analysis (DMTA), tensile test device, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. The effect of fiber length on the thermomechanical properties and crystallinity rate of the composites was investigated. The DMTA results showed that the storage modulus increases with the addition of CMFs. The X-ray diffraction studies, performed on the biocomposites, showed that the crystallinity rate of the blends was improved.

Open-source micro-tensile testers via additive manufacturing for the mechanical characterization of thin films and papers.

The cost of specialized scientific equipment can be high and with limited funding resources, researchers and students are often unable to access or purchase the ideal equipment for their projects. In the fields of materials science and mechanical engineering, fundamental equipment such as tensile testing devices can cost tens to hundreds of thousands of dollars. While a research lab often has access to a large-scale testing machine suitable for conventional samples, loading devices for meso- and micro-scale samples for in-situ testing with the myriad of microscopy tools are often hard to source and cost prohibitive. Open-source software has allowed for great strides in the reduction of costs associated with software development and open-source hardware and additive manufacturing have the potential to similarly reduce the costs of scientific equipment and increase the accessibility of scientific research. To investigate the feasibility of open-source hardware, a micro-tensile tester was designed with a freely accessible computer-aided design package and manufactured with a desktop 3D-printer and off-the-shelf components. To our knowledge this is one of the first demonstrations of a tensile tester with additively manufactured components for scientific research. The capabilities of the tensile tester were demonstrated by investigating the mechanical properties of Graphene Oxide (GO) paper and thin films. A 3D printed tensile tester was successfully used in conjunction with an atomic force microscope to provide one of the first quantitative measurements of GO thin film buckling under compression. The tensile tester was also used in conjunction with an atomic force microscope to observe the change in surface topology of a GO paper in response to increasing tensile strain. No significant change in surface topology was observed in contrast to prior hypotheses from the literature. Based on this result obtained with the new open source tensile stage we propose an alternative hypothesis we term ‘superlamellae consolidation’ to explain the initial deformation of GO paper. The additively manufactured tensile tester tested represents cost savings of >99% compared to commercial solutions in its class and offers simple customization. However, continued development is needed for the tensile tester presented here to approach the technical specifications achievable with commercial solutions.

Molecular deformation of wood and cellulose studied by near infrared spectroscopy

Wood (Eucalyptus regnans and Pinus radiata) and paper samples were stretched to different strain levels using a purpose-built tensile test device fitted into a near infrared (NIR) spectrometer while collecting transmission spectra. Consistent spectral changes caused by mechanical strain, assigned to OH stretching bands, were observed for all three sample types. Bands at 6286 ± 5 cm−1 and 6470 ± 10 cm−1 were tentatively assigned to the OH groups connected with the 2OH⋯6O and 3OH⋯5O intramolecular hydrogen bonds of crystalline cellulose Iβ, respectively. Both bands shifted to higher wavenumbers indicating the elongation of the hydrogen bonds. A linear relationship was found between band shifts and mechanical strain. Band shift rates for the 3OH bond were more than twice that of the 2OH bond, consistent with bending of the glycosidic bond. Bending tests showed that the band at around 6286 cm−1 shifted in opposite direction when under tension or compression.

EFFECT OF VARIOUS PULLING SPEEDS ON THE MECHANICAL PROPERTIES OF VARIOUS FIBER MIXTURE COMBINATIONS OF POLYAMIDE 6 AND 6.6 MATERIALS

Nowadays, thermoplastic composites have increasingly wide application areas due to their high stiffness and impact strength properties, superior fracture toughness, long duration of raw material shelf life and ease of production processes. Besides, they provide safer work environment. In this study, it has been examined that how the pulling speeds effects mechanical properties of thermoplastic composites. Non-reinforced, 15 percent reinforced and 30 percent reinforced polyamide 6 and polyamide 6.6 samples are produced with using plastic injection molding method and they are subjected to tensile testing at five different pulling speeds using the Tensile Testing Device. The results obtained from testing and those gathered from the plastics manufacturer company are compared with data obtained from the literature to check mechanical properties of thermoplastic composites which have been used in pulling speed test. It is observed that the experimental results were highly consistent with those in literature. According to these results, the positive effect of higher pulling speeds is observed. In this way, the different types of unreinforced and fiber glass reinforced polyamide 6 / polyamide 6.6 samples behavior under different pulling speeds have been determined. The results are in similar behavior with all types of polyamides. In order to gain an understanding of the effect of the overall testing procedure for all speeds, stress–strain graphics are constructed. Article DOI: https://dx.doi.org/10.20319/mijst.2018.41.162179 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Development of an Equibiaxial Tensile Test Device and Associated Test Method for Parameter Identification of Hyperelastic Ogden Model of Soft Material

Abstract Three different tensile tests are required to characterize a soft solid material that exhibits large deformations under external loading. The tensile tests include the uniaxial tensile, planar tensile, and equibiaxial tensile tests. In this study, a novel equibiaxial tensile test device was developed, and a test method combining the test device and a universal testing machine was proposed. Additionally, uniaxial tensile, planar tensile, and equibiaxial tensile tests of a silicone rubber were conducted, and stress-strain curves obtained from the three tests were then utilized to identify the parameter values of the hyperelastic Ogden model. The parameter values were validated by reconstructing the three tests in a finite element analysis software via the identified hyperelastic Ogden model. The findings indicated that the simulation results were in strong agreement with the test results. This validated the test method and the identified hyperelastic Ogden model. Furthermore, parameter values identified only by the uniaxial tensile test were used to perform the reconstruction analysis. The results of the analysis indicated that it was important to incorporate results from several types of tensile tests in the parameter identification process in order to obtain better simulation results.

Design, manufacture and test of a high temperature tensile and compression testing device

This paper describes the design and manufacture of a low-cost laboratory test device capable of testing metallic materials at elevated temperatures. The device, which consists of an environmental chamber, specimen gripping mechanism, and associated instrumentation, is fitted to a standard tensile-compression machine. Standard tensile test samples, notched specimens and compression test samples can be tested in the device at temperatures up to 1200oC. This paper describes the operation of the device and the results of a series of validation tests, on various metallic materials, carried out on the machine.

Fatigue performance of bituminous mixtures made with recycled concrete aggregates and waste tire rubber

Fatigue cracking is one of the main hot-mix asphalt (HMA) failure modes. The current laboratory investigation analyses the fatigue performance of HMA made with recycled concrete aggregates (RCA). An HMA type AC 22 bin S made with 0%, 35% and 42% of RCA was tested in the indirect tensile fatigue test (ITFT) device. Three constant stress levels, ranging from 150kPa to 350kPa were used. Mixtures were manufactured at the optimum bitumen content using two types of bitumen: a B35/50 penetration grade bitumen and a 10% waste tire rubber modified bitumen, BC35/50. This investigation demonstrates the beneficial effect on fatigue life of the incorporation of RCA. Additionally, the use of crumb rubber could lead to RCA bituminous mixtures with higher fatigue life in medium traffic roads.

A comparison of the material properties of natural and synthetic vascular walls

Characterization of the mechanical properties of native and synthetic vascular grafts is an essential task in the process of designing novel vascular constructs. The aim in this study was to compare the mechanical behavior of ovine left Subclavian artery with that of POSS-PCU (a commercial biomaterial which is currently under clinical investigation. ClinicalTrials.gov Identifier: NCT02301312). We used Delfino's strain energy potential within the framework of quasilinear viscoelasticity theory to capture the viscoelastic response of the considered materials. The material parameters of the quasilinear viscoelastic constitutive equation were determined through a combination of experimental and computational method. First, a uniaxial tensile testing device was used to perform a series of stress relaxation tests on ring samples. Then, the derived quasilinear viscoelastic models were implemented into finite element system. With the aid of mechanical experimentation and finite element simulation, the material parameters were obtained, modified and used for comparison of the mechanical properties of vascular walls. The results showed that the stiffness and the long term viscoelastic parameters of POSS-PCU may lead to different stress responses of the vascular walls. These two factors can be improved by modifications in manufacturing parameters of the synthetic vessel.

Tissue Perfusion Alters Mechanical Properties Of Human Tendons. A Human Cadaver Study

Tendons exhibit viscoelastic properties reflected by a non-linear force-deformation relation and energy loss upon stretching and release. It is known that tendons change mechanical properties acutely after loading, which is attributed in part to tissue viscosity. Although sparse, tendons are vascularized but whether blood flow or viscous pressure influences the mechanical properties acutely is unknown. Human cadaver specimens with intact vessels can be perfused at physiological pressure, which combined with tensile testing may yield information of the role of tissue perfusion on tendon function. PURPOSE: To examine if tissue perfusion influences the mechanical properties of tendons during loading and unloading. METHODS: Four fresh intact cadaver hand specimens were sectioned proximal to the processus styloideus. The a. ulnaris was cannulated to enable saline perfusion of the hand at physiological pressure. The flexor digitorum profundus tendon of the middle finger was mounted in a tensile testing device, and distally, the tip of the intact finger was clamped allowing repetitive loading of the tendon. Four series of 10 tendon loadings were conducted: 2 with perfusion and 2 series without. Series were separated by 5 min with or without perfusion. Subsequently the specimens were perfused with ink and upon dissection the vincular arteries were colored indicating that the tendons had received perfusion. RESULTS: Hysteresis was reduced over all series of loadings but the reduction was greater when the tissue was not perfused (40%) compared to loading series with perfusion (30%, P<0.05). Hysteresis recovered in rest periods, but recovery was doubled during perfused rest compared to rest without perfusion. Tendon stiffness increased through loading series but perfusion did not significantly influence the increase. However, reduction of tendon stiffness during rest periods was greater with perfusion (9%) compared to no perfusion (3%, P<0.05). CONCLUSIONS: Despite non physiological conditions the present data indicate that tissue perfusion may influence the mechanical properties of the force bearing tissues both with respect to stiffness and ability to store and release energy. It should be noted that a limited number of cadavers were available suggesting that caution be taken when data are interpreted.

Mechanical Properties of a Partially Solidified Cu-Zn Alloy

For predicting solidification cracking by thermal stress analysis, the mechanical properties in the partially solidified state based on the experimental results are the best hope. However, the Young’s modulus has never been investigated for copper alloys. In this study, stress–strain curves of a Cu-Zn alloy in the partially solidified state for various solid fractions were obtained using a specially developed horizontal tensile test device. Furthermore, by removing the load during the tensile test, the spring-back (elastic behavior) was observed and the Young’s modulus was obtained.

Tensile creep measurements of ordinary ceramic refractories at service related loads including setup, creep law, testing and evaluation procedures

Abstract 1 The performance of refractories under operating conditions is often influenced by tensile creep. This paper proposes a high-temperature tensile testing device which allows for long term creep measurements at operating loads. The chosen specimen geometry is more adequate for the testing of ordinary ceramic refractories which may be heterogeneous with respect to grain size (maximum grain size e.g. 5 mm) and chemical composition. For this application the innovative design exhibits not only improved specimen and loading alignments, but also reliable specimen holding and cooling systems. Specific procedures were followed to avoid uneven stress distribution along the specimen gauge length. The testing procedure was optimized by simulating experimental creep conditions with a finite element (FE) model built with the software Abaqus. Measurements were performed on magnesia–chromite material at different temperatures and applied stresses. Under these testing conditions, three creep stages emerged. The Norton-Bailey creep rate equation was employed to describe the creep behavior for the three stages. An evaluation using the Generalized Reduced Gradient (GRG) algorithm was then performed in order to identify the three creep stages and inversely estimate the Norton-Bailey creep parameters n , a and K for each stage.