Electronic Universal Testing Machine Research Articles

Preparation and Mechanical Properties of Short Carbon Fiber Networks Reinforced Anionic Polymerized Nylon 6 Composites

Short carbon fiber three-dimensional network reinforcement (SCFNR) was prepared by bonding two different lengths of short carbon fibers (SCF) with phenolic resin powder (PF), and then carbonized at 800 °C. Two kinds of SCFNR/anionic polyamide 6 (APA6) composites were fabricated via vacuum assisted impregnation process (VAI). The microstructures and mechanical properties of the composites were characterized by scanning electron microscopy and universal testing machine. The thermal stability of the composites was evaluated by thermogravimetric. The results show that the carbonized phenolic resin can effectively bond SCF to form a rigid three-dimensional network reinforcement, both types of SCFNR can significantly improve the mechanical properties of the composites. The maximum thermal decomposition temperature of SCFNR/APA6 composite prepared with the carbon fiber length of 1 mm is 150 °C higher than that of APA6

The study of microstructure and mechanical properties of Ti6Al4V/MB3 metallurgical joint by tungsten inert gas welding-brazing process

MB3 Mg alloy and Ti6Al4V alloy were joined by tungsten inert gas (TIG) welding-brazing process with AZ91 filler. The microstructures and mechanical properties of Ti-Mg weld were analyzed by optical metalloscope, scanning electron microscope and universal testing machine. Results reveal that Ti-Mg dissimilar alloys were successfully joined by TIG welding-brazing process. A Ti-Al intermetallic compound layer formed at the brazing area, and grain coarsening accompanied with Mg17Al12 precipitates occurred in the fusion area. The former is the key to realize the reliable joining of Ti-Mg, whereas the latter is the week point of whole joint. Besides, under optimized welding parameter of 65 A, the maximum mechanical property of 202 N mm−1 was obtained and fracture location was at the fusion area.

Effects of pre-stretching on microstructure and properties of WE43A-alloy after aging treatment

ABSTRACTEffects of pre-stretching on microstructure and mechanical properties of WE43A alloy were investigated by optical microscope, transmission electron microscope, scanning electron microscopy and electronic universal material testing machine. The experimental results showed that a large number of dislocations and twins were formed in the matrix with the increase of deformation strain. During subsequent aging, β1 phases precipitated in dislocation area and distributed in matrix in a combined manner, honeycomb network and random. The precipitation of β1 increased the ultimate tensile strength and yield strength of WE43A alloy to 272 and 241 MPa, in comparison with the samples without pre-stretching (226 and 180 MPa). The fracture morphology of sample with strain 9% was transgranular cleavage fracture.

Compressive properties and micro-structural characteristics of Ti–6Al–4V fabricated by electron beam melting and selective laser melting

Bulk Ti–6Al–4V material and its lattice structures with rhombic dodecahedron unit cells are fabricated by electron beam melting (EBM) and selective laser melting (SLM) method respectively. The effect of part size on the compressive properties and failure modes of the material is taken into consideration. Electronic universal testing machine and Split Hopkinson pressure bar (SHPB) system are adopted for experiments, and the compressive behavior of the additively manufactured materials is investigated accordingly. Meanwhile, multiscale observations are conducted to reveal the macro- and microscopic deformation mechanism. The results showed that the mechanical response of the dense struts as well as micro-lattice structures manufactured by the two processes are quite different. The geometric imperfections are considered to reduce the strength of the undersized struts prepared by EBM. The specimens fabricated by both of the two approaches exhibit elastic-plastic deformation. Besides, the SLM made material is found to be more sensitive to strain rate especially for that below 1000/s than the EBM parts.

The potential use of cross-linked alginate/gelatin hydrogels containing silver nanoparticles for wound dressing applications

In this study, alginate/gelatin (Alg/Gel) hydrogels containing silver nanoparticles (AgNPs) cross-linked with 1.0, 2.5, and 5.0% w/v calcium chloride (CaCl2) were fabricated using solvent casting method. The morphology and mechanical properties of Alg/Gel hydrogels containing AgNPs were observed by scanning electron microscopy and universal testing machine. The mechanical performance demonstrated that the Alg/Gel hydrogels containing AgNPs cross-linked with CaCl2 showed improved mechanical properties with increasing CaCl2 concentration. The water swelling and weight loss behaviors of these hydrogels were investigated in an acetate buffer solution. Increasing concentration of CaCl2 from 1.0 to 5.0% w/v, the hydrogels manifested the lower swelling and weight loss behaviors. For in vitro AgNP release, the results showed that the released silver (Ag+) ions amount from the hydrogels cross-linked with 5% w/v CaCl2 was the highest followed by those of 1.0% and 2.5% w/v CaCl2, respectively. Moreover, these hydrogels showed the antibacterial activity against S. aureus, P. aeruginosa, and E. coli. Lastly, these hydrogels were non-toxic to both NHDF and NCTC clone 929 cells. Thus, these Alg/Gel hydrogels containing AgNPs had a potential for use in various wound dressing and biomedical fields.

Effects of different silane coupling agents on structure and properties of starch–chitosan–kaolin composites

ABSTRACTEffects of different silane coupling agents on clay surface modification were studied. Herein, functionalized superfine kaolin was compounded with starch–chitosan (SCS) to prepare starch–chitosan‐functionalized superfine kaolin composite. The characterization results showed that kaolin (K) was successfully modified; the composite formed a dense intercalated structure. The glass‐transition temperature (T g) was measured by differential scanning calorimetry and dynamic mechanical analysis. It decreased by 60 °C which attested the crystallinity of SCS. The results of thermogravimetric analysis showed that the fastest weight‐loss temperature (Tmax) was elevated by over 50 °C for composites. Mechanical properties of the composites were explored by electronic universal testing machine. Tensile strength and elongation of composites were improved by 4.7 and 10.9 times. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48050.

Effects of laser processing parameters on microstructure and mechanical properties of additively manufactured AlSi10Mg alloys reinforced by TiC

AlSi10Mg alloys reinforced by TiC particles were fabricated on 5052 aluminum alloys by laser additive manufacturing. The surface morphology, microstructure, microhardness, and tensile properties of the alloys fabricated with different processing parameters were investigated by optical microscope (OM), scanning electron microscope (SEM), Vickers hardness tester, and high-precision electronic universal testing machine. The results show that appropriate laser energy input leads to uniform distribution of TiC particles in the alloy. Fine needle-like TiC particles are precipitated from the grain boundary, which is beneficial to the improvement of mechanical properties of the alloy. The optimum process parameters are found to be 2500–3500 W for laser power, 600 mm/min for scanning velocity, and 2.0 mm for hatch spacing. For lower or higher laser energy input, aggregations are formed in the coatings. At the optimum processing parameters, the maximum microhardness and tensile strength of the TiC/AlSi10Mg alloys are much higher than those of others, which are 139.1 HV0.05 and 278.8 MPa, respectively. A large number of dimples have been found on the fracture surface of the alloys, which indicates the fracture mechanism of the alloy is ductile fracture.

Designing a castor oil-based polyurethane as bioadhesive

Based on the stealth behavior of castor oil and poly(ethylene glycol), we selected a polyurethane system to obtain an ideal surgical adhesive. The polyurethane adhesives with varying concentrations of castor oil were investigated by Fourier transform infrared spectrometer, differential scanning calorimetry, scanning electron microscopy, goniometer, and universal testing machine. Curing results show that a 7-min to 25-min room temperature curing can be achieved, providing one possibility of shortening the surgery time. In vitro biodegradation test demonstrates that a certain proportion of the polyurethane film will be hydrolyzed in a foregone manner after a period of time (7 weeks). The adhesion strengths of these adhesives show a strong bonding between pieces of tissue, which makes them qualified for application in a moist environment.

Effect of component and surface structure on poly(l-lactide-co-ɛ- caprolactone) (PLCA)-based composite membrane

To obtain an ideal guided bone tissue regeneration (GBR) membrane, a novel double-layered composite membrane was developed by combining the technology of solvent casting and electrospinning, which was composed of poly (l-lactide-co-ɛ-caprolactone) (PLCA) cast layer and Mg-substituted nano-hydroxyapatite (Mg-n-HA)/PLCA composite electrospun layer. The effect of different Mg-n-HA contents of 10 wt%, 20 wt%, 30 wt% and 40 wt% and membrane surface porous structure on mechanical properties, in vitro apatite deposit, cell biocompatibility and in vivo tissue regeneration of the composite membrane were investigated, using electronic universal testing machine, scanning electron microscope (SEM), in vitro simulated body fluids (SBF) soaking, cell culture experiment and in vivo skulls repair experiment of rabbits. The results showed that the addition of Mg-n-HA did not bring about negative effect on the mechanical properties, porous structure consisting of nanofibers and the degradation rate of the composite membrane. Instead, the high Mg-n-HA content and membrane surface porous structure greatly promoted the apatite deposit. Moreover, the Mg-n-HA/PLCA composite double-layered membranes displayed better cell proliferation and tissue biocompatibility, suggesting it had a great potential to be used as GBR membrane.

Activated B Lymphocyte Inhibited the Osteoblastogenesis of Bone Mesenchymal Stem Cells by Notch Signaling.

Estrogen is very important to the differentiation of B lymphocytes; B lymphopoiesis induced by OVX was supposedly involved in osteoporosis. But the effects of B lymphocytes on the osteogenic differentiation of bone mesenchymal stem cells (BMSCs) are not clear. In this study, we detected bone quality and bone loss in a trabecular bone by electronic universal material testing machine and microcomputed tomography (micro-CT) in OVX and splenectomized-ovariectomy (SPX-OVX) rats. Additionally, changes in lymphocytes (B lymphocyte, CD4+ and CD8+ T lymphocytes, and macrophages) in the bone marrow were analyzed by flow cytometry. The osteogenesis of BMSCs cocultured with normal and LPS-pretreated B lymphocytes was detected by BCIP/NBT and Alizarin red S staining. Measurement of the Notch2, Notch4, Hey1, Hey2, Hes1, and runt-related transcription factor 2 (Runx2) expression in BMSCs cocultured with B lymphocytes was done using real-time PCR. The effects of dexamethasone and DAPT (inhibitor of Notch signaling) on osteogenesis of BMSCs were detected by BCIP/NBT, Alizarin red S staining, and real-time PCR. Osteoporosis happened in OVX rats, more serious in SPX-OVX rats, B lymphocytes increased in OVX rats, and sharply higher in SPX-OVX rats. Osteoporosis did not happen in SPX rats which is still companied with a high increase of B lymphocytes. LPS-pretreated B lymphocytes suppressed the osteogenesis of BMSCs, but the normal B lymphocytes could not. The LPS-pretreated B lymphocytes upregulated the expression of Notch4, Hes1, and Hey2 and downregulated the expression of Runx2 in BMSCs. Dexamethasone and DAPT could downregulate the high expression of Notch4, Hes1, Hey2 and upregulate the low expression of Runx2 in BMSCs which cocultured with LPS treated B lymphocytes, the inhibited ALP and Alizarin red staining in BMSCs which cocultured with LPS treated B lymphocytes also partly restored.

Biomimetic preparation of a ceramic combined with sea urchin stereom structure and nacre mineral bridge structure

Multibiological multiscale biomimetic design is a novel bionic idea that involves multi-mechanisms. Porous ceramics with a sea urchin stereom structure on a micrometre scale and a nacre mineral bridge structure on a submicron scale have been fabricated via organic foam impregnation and controlled crystallisation. The microstructure and mechanical properties of biomimetic ceramics are, respectively, characterised using scanning electron microscopy and universal testing machine. Moreover, the porosity, reliability and grain boundary stress of biomimetic ceramics are calculated via Archimedes method, Weibull theory and finite element method, respectively. Results show that the ceramic produced in this work has a porosity of 88.16% and an average pore size of 284.65 μm. Mineral bridges of Al2TiO5 with a thickness of 30–230 nm are widely and randomly distributed in the grain boundary glass phase of Al2O3 and improved the compressive strength (2.32 MPa) and Weibull modulus (7.85) of ceramics by the multi-mechanisms of crack deflection, reducing maximum stress and homogenising stress on the grain boundary. These investigations would be of great value to the design and synthesis of novel biomimetic materials.

Effect of different mixing modes of enoxaparin sodium on biomechanics of bone cement

Objective To observe the biomechanical effects of enoxaparin sodium added to bone in different mixing modes. Methods The enoxaparin sodium for injection was mixed with polymethylmethacrylate (PMMA) bone according to different dosages and different mixing methods. Group A was used as blank control group without enoxaparin sodium. Groups B (8 000 AxaIU), C (16 000 AxaIU) and D (24 000 AxaIU) served as control groups in a powder mixture. Groups E (8 000 AxaIU), F (16 000 AxaIU) and G (24 000 AxaIU) served as experimental groups. The enoxaparin sodium for injection was dissolved and added to the PMMA bone cement. Under the environment of sterility, temperature (23±1) ℃, relative humidity higher than 40% (operating room environment), according to the international standard ISO5833: 2002 Implants for surgery-Acrylic resin cement regulations, bone cylinder specimens and cuboid specimens were prepared. After measurement and X-ray irradiation, 5 specimens of each group were selected, and the compressive strength, flexural strength and flexural modulus were measured on an electronic material universal testing machine. Results The compressive strength, flexural strength and flexural modulus in groups E, F and G were significantly lower than those in the control groups (t=12.731, 41.646, 3.128, P<0.05). The lowest values were (57.17±1.15) MPa, (67.93± 0.55) MPa, and (19.2± 0.114) GPa respectively. Conclusion The addition of enoxaparin sodium to PMMA bone in a liquid mixture can significantly reduce the biomechanical properties of bone cement. Key words: Polymethylmethacrylate bone cement; Enoxaparin sodium; Biomechanics

Interfacial characterization and mechanical properties of 316L stainless steel/inconel 718 manufactured by selective laser melting

The multi-material selective laser melting (SLM) technology has been widely studied in recent years. In this paper, 316L stainless steel (316SS) and Inconel 718 (IN718) multi-material parts were manufactured by SLM and their interfacial characteristics and mechanical properties were investigated by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electronic universal testing machine and microhardness tester. The interface metallograph and higher comprehensive mechanical performance with elasticity modulus (103 ± 3 MPa), elongation (28.1 ± 2%) and ultimate tensile strength (596 ± 10 MPa) proved good metallurgical bonding at the interfaces (∼100 μm) between 316SS and IN718. Nevertheless, some cracks and holes, which were found at or near the interfaces, suggested special SLM processing parameters (such as laser power, laser scanning speed, layer thickness, hatch spacing, remelting, fabrication sequence and layers of interface) should be applied at the interfaces.

Effect of saturation on mechanical behavior of cement mortar based on 8-type tensile test

Based on the purpose of revealing the effect of saturation on static tensile mechanical behaviour of cement mortar, the single-axis static tensile test was carried out for 8-type cement mortar specimens with the saturation of 0%, 50%, and100% respectively. The WDW-20 microcomputer controlled electronic universal testing machine was used in this paper. The date obtained from test indicates that the stress-strain curves of different saturation cement mortar are similar, stress with strain increases, the stress growth rate increases gradually. With the increase of saturation, the static tensile strength of cement mortar gradually decreases, and the stiffness of cement mortar gradually decreases, and the deformation performance gradually improves, and the maximum tensile strain increases gradually. Compared with dry cement mortar specimens, the tensile strength of saturated cement mortar specimens is decreased by 23.36%; the maximum tensile strain of semi-saturated and saturated cement mortar specimens is increased by 4.79% and 23.43% respectively. The elastic modulus of the dry and the semi-saturated cement mortar specimens are similar, when they are under pulled, and are larger than the elastic modulus of saturation cement mortar specimens.

Microstructure and mechanical properties of TiC/AlSi10Mg alloy fabricated by laser additive manufacturing under high-frequency micro-vibration

TiC/AlSi10Mg alloys were successfully fabricated by laser additive manufacturing under high-frequency micro-vibration. The application of high-frequency micro-vibration during laser processing could accelerate the melt flow, promote the floating of gas and slag in the molten pool and significantly reduce the pores in the alloys, which could obtain refined and homogenous microstructure with superior alloy density as well as good performances with relatively high production efficiency. The effects of different vibrational frequencies on the microstructure and properties of the alloys have been systematically investigated. The microstructure, chemical composition, phase constituent, hardness distribution and tensile properties of the TiC/AlSi10Mg alloys were investigated by optical microscope (OM), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffractometer (XRD), Vickers micro-hardness tester, and high-precision electronic universal testing machine, respectively. The results shows that the structures of the TiC/AlSi10Mg alloys are refined by high-frequency micro-vibration. The size of the cellular grain is decreased from 4 to 13 μm to 2–4 μm. The overlap region of the molten pool could be divided into three parts: fine zone, coarse zone and heat affected zone (HAZ). The number of pores in the alloys is reduced by high-frequency micro-vibration and the density of the alloys is effectively improved. When the vibration frequency is 969 Hz, the structure is more compact and the defect in the alloy is the lowest, providing a good density (99.1%). In addition, the maximum average hardness is 183.3 HV0.05 at the vibration frequency of 969 Hz, and the maximum tensile strength and elongation are 314.7 MPa and 8.81% respectively at this vibration frequency, which are higher than those at other vibrational frequencies.

Dynamic response and failure mechanism of Ti-6AL-4V hi-lock bolts under combined tensile-shear loading

This paper is focused on the dynamic mechanical behavior and failure characteristics of Ti-6AL-4V hi-lock bolt (HLB) under combined tensile-shear loading. Firstly, the dynamic mechanical properties of Ti-6AL-4V alloy under the quasi-static, intermediate strain rate and high strain rate are investigated by using an electronic universal testing machine, a high velocity hydraulic servo-testing machine and Split Hopkinson Pressure Bar (SHPB). A Johnson-Cook model is established to describe the dynamic constitutive relationship of Ti-6AL-4V alloy on the basis of the experimental results. A novel experimental fixture and a new collision-type loading method are proposed to investigate the dynamic failure characteristics of HLB. The dynamic pure tensile, 30° tensile-shear coupling, 45° tensile-shear coupling, 60° tensile-shear coupling, pure shear experiments of HLB are conducted at the velocities of 0.01 m/s, 0.1 m/s and 1 m/s, respectively. Furthermore, a finite element model is established to validate the experimental results, and good agreement is obtained between the experimental and the simulation results. The experimental results show that the failure mode and the failure load of the HLB are greatly affected by the loading condition but less by the loading speed.

Preparation and biomechanics of new enoxaparin sodium bone cement

Objective To explore the preparation of new enoxaparin sodium bone and its biomechanics. Methods The enoxaparin sodium injection was mixed with polymethylmethacrylate (PMMA) bone at different doses and divided into seven different mass fractions: A (0 AxaIU), B (4 000 AxaIU), C (8 000 AxaIU), D (12 000 AxaIU), E (16 000 AxaIU), F (20 000 AxaIU) and G (24 000 AxaIU). In the operating room environment, the final setting time was measured by standard Vicat instrument. According to the ISO5833: 2002 Implants for surgery-Acrylic resin cement , we made the cemented cylinder specimens and cuboid specimens. The compressive strength, flexural strength and flexural modulus were measured on the electronic material universal test machine. Results The final setting time in A-G groups was (9.52±0.09), (9.48±0.08), (9.46±0.11), (9.48±0.08), (9.56±0.11), (9.68±0.08) and (9.74±0.15) min. The biomechanical results showed that the compressive strength, flexural strength and flexural modulus in the A-G groups decreased with the increase of the dose of enoxaparin sodium for injection. The lowest values of compressive strength, flexural strength and flexural modulus of each group were (83.75±0.42) MPa, (86.65±0.62) MPa, and (2.11±0.12) GPa, which were higher than the international standards. Conclusion The enoxaparin sodium injection can be added to the PMMA bone cement. When it is not higher than 8 000 AxaIU, it will not have a significant effect on the mechanical properties of the bone cement, which fulfills the biomechanical requirements of clinical application. Key words: Enoxaparin sodium; Bone cement; Biomechanies; Thrombus

Effect of laser remelting on microstructure and wear resistance of plasma sprayed Al2O3-40%TiO2 coating

The Al2O3-40%TiO2 coating fabricated by plasma spraying on carbon steel substrate were remelted by laser, and the effect of laser remelting on microstructure and wear resistance of plasma sprayed Al2O3-40%TiO2 coating were studied. The microstructure and phase composition of plasma sprayed and laser remelted coatings were analyzed using scanning election microscopy (SEM), energy disperse spectroscopy (EDS) and X-ray diffraction(XRD). The micro-hardness and adhesion strength of two coatings were measured using micro-hardness tester and electronic universal tensile testing machine. The wear resistance of two coatings was tested through a slurry rubber wheel abrasion test machine, and the wear behaviour was also studied by SEM.The results show that metastable phase γ-Al2O3 in coating is completely transformed into stable phase α-Al2O3 after laser remelting. The laser remelted coating becomes much denser, and then its microhardness and adhesion strength have been greatly improved. The laser remelted coating exhibits better wear resistance compared to the plasma-sprayed coating, and the main wear mechanism responsible for wear was microcrack and fracture wear.

Preparation and characterization of magnetorheological elastic polishing composites

Magnetorheological elastic polishing composites, a new type of polishing material using magnetorheological elastomers as a binder, were developed to solve the problems of low processing efficiency and difficulty controlling the machining process in current polishing technology. A set of heat–magnet–force-coupled devices was designed and used to prepare isotropic and anisotropic silicon rubber–based magnetorheological elastic polishing composites by magnetic field–assisted compression molding technology. Then, the microstructure and properties of magnetorheological elastic polishing composites were characterized by X-ray diffraction, optical microscope, electronic universal testing machine, and microscratch tester. The results show that magnetorheological elastic polishing composite is a polymer-based composite composed of rubber and micro/nanoparticles, and the magnetic field applied during the preparation process causes the interior of the magnetorheological elastic polishing composites to appear as chains and columns formed by iron particles. The compressive elastic modulus and scratch resistance of magnetorheological elastic polishing composites increase with the increase in the surrounding magnetic field strength. The main reason for the above phenomena is related to the change in the microstructure of magnetorheological elastic polishing composites induced by an external magnetic field. Finally, a simple application of magnetorheological elastic polishing composites in polishing proves that magnetorheological elastic polishing composites can be applied to mechanical processing to achieve magnetically controlled polishing.

Preparation and properties of fluorosilicone polyether polyurethane underwater acoustically transparent encapsulant

Fluorosilicone polyether polyurethane (FSPU) was successfully prepared from polytetramethylene glycol, hydroxyl fluorosilicone oil, toluene diisocyanate and chain extender 2,4-diamino-3,5-dimethylthiotoluene. The obtained material was characterized by Fourier transform infrared spectroscopy, dynamic mechanical analysis and scanning electron microscopy. And the water resistance, mechanical and acoustic performance of the materials were tested by video optical contact angle measuring instrument, electronic universal testing machine and sound field, respectively. The results showed that the glass transition temperature of FSPU was lowered and the cold resistance was improved with the addition of hydroxyl fluorosilicone oil. When the amount of hydroxyl fluorosilicone oil was 40 wt%, the water contact angle of FSPU increased to 113.6°, and the water absorption reached a minimum of 0.7%. Compared with polyurethane, the hydrophobic performance of FSPU was significantly improved. The insertion loss of FSPU-40 at 1000 kHz was only 220.60 dB/m, which was 68.7% lower than that of polyurethane. Above all, FSPU has excellent water resistance, cold resistance and acoustic performance, and is an ideal material for underwater acoustically transparent encapsulant.