Strength Of Test Specimens Research Articles

Enhancement of the Tensile and the Compression Properties for Heat- Cured Acrylic Resin Denture Base Materials

This work aims to investigate the tensile and compression strengths of heat- cured acrylic resin denture base material by adding styrene-butadiene (S- B) to polymethyl methacrylate (PMMA). The most well- known issue in prosthodontic practice is fracture of a denture base. All samples were a blend of (90%, 80%) PMMA and (10%, 20%) S- B powder melted in Oxolane (Tetra hydro furan). These samples were chopped down into specimens of dimensions 100x10x2.5mm to carry out the requirements of tensile tests. The compression strength test specimens were shaped into a cylinder with dimensions of 12.7mm in diameter and 20mm in length. The experimental results show a significant increase in both tensile and compression strengths when compared to control (standard) results for the preparation material.

Mechanical Performance of Prefabricated External Wall Panel under Horizontal Displacement

In this paper, experiment and Finite Element Method (FEM) approaches are employed to study the mechanical performance of prefabricated external wall panel under lateral displacement. Tensile bond strength test and Z-shaped specimen direct shear test of the bonding interface of mortar to ceramsite concrete are performed, the normal and shear mechanical property of the interface is studied respectively. Scaled model test of prefabricated external wall panel under lateral displacement is then performed to obtain load-displacement curve, and mechanical behavior of prefabricated external wall panel in different stages is studied. Moreover, ABAQUS finite element analysis model for scaled model test panel is established based on previous study about bond interface and the results from experiment and FEM analysis are relatively consistent with each other. It is found that with the gradual increase in tangential contact stiffness of joint interfaces, the overall lateral stiffness of wall panels will approach complete joint consolidation conditions before the peak load. However, when the tangential contact stiffness of joint interfaces increases to a certain extent, there will be little change in initial lateral stiffness.

Specimen size effects on fracture behaviour of SiC/SiC tubes during circumferential tensile test

SiC fiber-reinforced SiC matrix (SiC/SiC) composites are expected as a high-temperature structural material for the application of aerospace and nuclear energy system due to their high-temperature stability, reduced-activation property, and excellent irradiation resistance. It was investigated the size effects of test specimen on the fracture behaviour and apparent strength of SiC/SiC tubes in order to minimize the size of test specimen, as well as to develop circumferential tensile test method for SiC/SiC fuel cladding of nuclear reactor. The tube specimens with a narrow width (less than 5 mm) represented the stable value of apparent strength. In case of wide width (>5 mm), the apparent strength of test specimen decreased with the increase in specimen width. It was observed that the fracture of the test specimen with wide width was initiated from the sides of test specimen due to the local contact between loading pin and the test specimen. It is required to use the material with high modulus as a loading pin material in order to avoid the stress concentration caused by local contact.

PERBANDINGAN KEKUATAN BETON DENGAN CAMPURAN DRAMIX STEEL FIBER DAN TULANGAN WIREMESH PADA RIGID PAVEMENT (Comparison of the Strength of Concrete with a mixture of Dramix Steel Fiber and Wiremesh Reinforcement on Rigid Pavement)

ABSTRACTConcrete has a weakness that is having a low tensile strength and brittle so that the concrete is given steel reinforcement to anticipate it. In this study, the concrete mixture was added with dramix steel fiber. This addition was carried out to study and determine the effect of dramix steel fiber on compressive strength, flexural strength on normal quality concrete with the addition of 0%, 10%, 20% and 30% in compressive loads. Compressive strength specimens in the form of cylinders with a diameter of 15 cm and a height of 30 cm and bending strength test specimens in the form of blocks with a length of 60 cm, width of 15 cm and height of 15 cm. Testing is done after 28 days. Concrete with the addition of dramix steel fiber is 30% more capable of producing a higher compressive strength than the others. The addition of dramix steel fiber resulted in an average compressive strength of 0%, 29.07 MPa, 10%, 29.33 MPa, 20%, 29.40 MPa, 30%, 29.58 MPa. For the highest flexural strength of concrete in the 15/15/60 beam sample, that is in the concrete mixture and the addition of dramix steel fiber of 5.44 MPa, it is higher than the addition of reinforcement iron m8, which is 4.96 MPa.Keywords:Dramix Steel Fiber, compressive strength, concrete flexural strength, m8 wiremesh

The Effect of Nano- ZrO2 and nano-Al2O3 Reinforcement on Flexural and Impact Strength of Repaired Acrylic Denture Base

Purpose: This study was conducted to evaluate the effect of reinforcementof different concentrations of nano-ZrO2 and nano-Al2O3 on the flexural strength and impact strength of repaired acrylic resin denture bases. Materials and Methods: A total of 100 specimens were prepared from heat-polymerized acrylic resin and then they were equally divided for the flexural and impact strength tests. 50 specimens were assigned for each testing group. For the flexural strength testing, metallic rectangular molds with rectangular-shaped (65 mm length x10 mm width x 2.5 mm thickness) were prepared. While specimens for the impact strength testing were prepared using rectangular-shaped molds with dimensions of (50 mm length x6mm width x4mm thickness). The prepared intact specimens were cut vertically in two halves along their long axis. For the flexural and impact strength testing, a repair gap was done. Specimens for each strength test were divided into one control group (specimen repaired with autopolymerizing acrylic resin with no fillers) and two repair groups with 2 concentrations (2% and 5%) of nano-ZrO2 fillers and two repair groups with 2 concentrations (2% and 5%) of nano-Al2O3 fillers. Flexural strength was measured using an Instron mechanical testing machine and impact strength was measured by Izod impact tester. Results: For the flexural strength results, the highest flexural strength was recorded with the 5% nano-ZrO2 fillers repair group followed by the 2% nano-ZrO2 group which also recorded higher significant mean value than the control group. In both nano-Al2O3 groups, there was a highly significant reduction in the flexural strength for both concentrations. For the impact strength results, the highest impact strength was recorded for the 2% nanoZrO2 fillers repair group followed by the 5% nano-ZrO2 group which also recorded higher significant mean values than the control group. In the 2% nano-Al2O3 repair group, there was a non-significant difference in the impact strength mean values compared with the control group. While the repair group reinforced with 5% nano-Al2O3 showed significant reduction in impact strength.Conclusions: The incorporationof nano-ZrO2 into repair resins may improve the flexural and impact strength of the repaired denture base whereas nano-Al2O3 caused reduction of both strengths.

Dentin Bond Strength of Experimental Composites Containing Bioactive Glass: Changes During Aging for up to 1 Year.

To investigate dentin bond strength of experimental composites based on a bis-GMA/TEG-DMA composite filled with a varying amount (0 to 40 wt%) of bioactive glass 45S5 (BG) at a total filler content of 70 wt%. Specimens for shear bond strength testing (diameter = 3.12 mm, height = 3 mm) were bonded to human dentin using a two-step self-etch adhesive and subjected to aging in water at 37°C for 1 week, 1 month, 3 months, 6 months, and 1 year. A total of 600 specimens were prepared (6 materials × 5 aging times × 20 specimens per experimental group). Bond strength was tested by loading specimens in a universal testing machine at a constant crosshead speed of 0.5 mm/min until fracture. Reliability analysis was performed using Weibull statistics. Experimental composites with a low BG content (up to 5 wt%) showed dentin bond strength and reliability comparable to those of the commercial reference composite. A further increase in the BG amount diminished both bond strength and reliability. The bond strength decline was linearly dependent on the amount of BG when observed within each aging time. One-year aging in water caused no deterioration of bond strength, but diminished bond reliability. The reliability after 1-year aging was similar among all composites, including the commercial reference composite. The variation in BG amount diminished the bond strength and reliability in a dose-dependent manner.

Development of hybrid aluminium metal matrix composite and study of property

Hybrid metal matrix composites are advanced materials used for light weight high strength applications in aerospace and automobile sector. Among the various techniques employed in fabricating hybrid metal matrix composites stir casting technique is simple and economical. The metal matrix choice was Aluminium 6061and the reinforcements are Zirconium di oxide (ZrO2) and Aluminium oxide (Al2O3) respectively. Aluminium 6061 was chosen due to its excellent cast ability, compatibility and application in aerospace and automotive sector. The key objective of exploiting zirconium di oxide as one of the reinforcement was, ZrO2adopts amonocliniccrystal structureat room temperature and transitions totetragonalandcubicat higher temperatures and holds very high refractory property. The key cause of selecting Aluminium oxide as one of the reinforcement includes that it possess a very high wear resistant property. The composite comprises of 90% of aluminium 6061, 5% of ZrO2 and 5% of Al2O3 which was restricted to 10 weight percentage in order to prevent cluster formation and to reduce weight. The average size of the reinforcing particle was 55-65 microns in order to attain good bonding with metal matrix. The developed composite casting was cut using wire EDM and test specimens were prepared .The various test consist of, micro graph study, tensile strength test, micro hardness test wear test and corrosion behaviour test. Micro graph study was carried and the images reveal the availability of reinforcement particles in the metal matrix phase. Tensile strength test specimens were cut as per ASTM- E8 standard, and the readings were tabularized. The tensile value show significant improvement. The hardness test was performed using Vickers micro hardness tester and its maximum value is 82.9 at 200kgf load. This accounts 70% increase when evaluate with parent alloy. Wear test was performed using pin on disc Ducom wear test device and the result shows significant increase in wear resistant property when compare with ground alloy Al6061. This is due to the excellent tribological property of ZrO2 and Al2O3. This research work comprises of successful invention of hybrid metal matrix composite with elevated property.

Enhancement of the Tensile and the Compression Properties for Heat- Cured Acrylic Resin Denture Base Materials

This work aims to investigate the tensile and compression strengths of heat- cured acrylic resin denture base material by adding styrene-butadiene (S- B) to polymethyl methacrylate (PMMA). The most well- known issue in prosthodontic practice is fracture of a denture base. All samples were a blend of (90%, 80%) PMMA and (10%, 20%) S- B powder melted in Oxolane (Tetra hydro furan). These samples were chopped down into specimens of dimensions 100x10x2.5mm to carry out the requirements of tensile tests. The compression strength test specimens were shaped into a cylinder with dimensions of 12.7mm in diameter and 20mm in length. The experimental results show a significant increase in both tensile and compression strengths when compared to control (standard) results for the preparation material.

Use of Sewage Sludge Ash and Hydrated Lime to Improve the Engineering Properties of Clayey Soils

Using various additives has been considered as one of the most common stabilization methods for improvement of engineering properties of fine-grained soils. In this research the effect of sewage sludge ash (SSA) and hydrated lime (HL) on compressive strength of clayey soil was investigated. For this purpose, 16 kinds of mixtures or treatments were made by adding different amounts of SSA; 0, 5, 10 and 15% by weight and HL; 0, 1, 3 and 5% by weight of a clayey soil. First, compaction characteristics of the treatments were determined using Harvard compaction test apparatus. So that, 12 unconfined compressive strength test specimens were made using Harvard compaction mold from each treatments taking into account four different curing ages, including 7, 14, 28 and 90 days in three replications. Therefore, a total of 192 specimens were prepared and subjected to unconfined compressive strength tests. The results of this study showed that the maximum dry density of the treated soil samples decreases and their optimum water content increases by increasing the amount of SSA and hydrated lime in the mixtures. It is also found that the adding of HL and SSA individually would increase the compressive strength up to 3.8 and 1.5 times respectively. The application of HL and SSA with together could increases the compressive strength of a clayey soil more efficiently even up to 5 times.

Prediction of unsaturated shear strength of expansive clays

The aim of this study is to predict the unsaturated shear strength of two locally expansive clays available in Saudi Arabia over a wide range of suction. A variety of prediction models categorised as semi-empirical or micromechanical were considered to examine their viability to estimate unsaturated shear strength of these clays over a wide range of suction. Soil water characteristic curves and effective shear strength parameters for both expansive clays were evaluated to serve as input for the prediction of unsaturated shear strength functions (USSFs). To verify the predicted USSF, data for unsaturated shear strength as a function of matric suction were generated from a series of unconfined compression strength (UCS) test specimens with different moisture (suction) levels. Comparison between experimental data and predicted USSF revealed that there is great discrepancy between predicted and experimental data; especially in the high-suction range; this was attributed to the emergence of desiccation cracks during drying. As an alternative approach, function fitting models were used and their viability was discussed.

KARAKTERISTIK SIFAT MEKANIS DAN STRUKTUR MIKRO PROSES AUSTEMPER PADA BAJA KARBON S 45 C DAN S 60 C

Abstract: Steel is an iron-carbon alloys containing concentrations of other alloys having a different composition and treatment materials, steel properties can be changed by heat treatment. The heat treatment process serves to increase the strength of a steel material. The nature of the material can be turned into a more robust and resilient heat treatment process, if done properly and correctly. Austempering process is just one example of the heat treatment process at steel that aims to improve the mechanical properties of the steel S 45 C and S 60 C. austempering process performed on the steel S 45 C and S 60 C aims to increase the hardness and toughness of the steel. Austempering process is done by austenisasi advance with temperature 8500C and held for 60 minutes, after which the process is carried out with 3 election austempering temperature of 3500C, 4500C, 5500C and held for 30 minutes. The method used to test the results of austempering is tensile testing using ASTM A370- 12a, Vickers hardness test and microstructure observation using a digital microscope. In the test results tensile steel S 45 C and S 60 C values obtained an increase in ductility and toughness of 17.1 % on steel S 45 C and 17 % on steel S 60 C. This value is obtained from the calculation of ultimate tensile strength test specimens that have not been in austempering process with a specimen that has been in the process of austempering at 3500C , and the results of testing hardness of the steel S 45 C and S 60 C obtained hardness value of 44% increase in steel S 45 C and 46 % on steel S 60 C. value this is obtained from the calculation of the average value of the test specimen is not in the process of austempering with a specimen that has been in the process of austempering at 3500C .

In-plane shear compression behaviour of steel-glass composite beams with laminated glass webs

Steel-glass composite beams with the combination of glass webs and steel flanges are known to be able to attain good ductility in contrast to pure glass panels. As a concentrated load is introduced away from the middle of the beam span, its resultant stress concentration can induce shear compression failure on the glass web which is distinguished itself from flexure failure as reported in the literature. This paper presents an experimental study on the in-plane shear compression behaviour of composite beams with laminated glass webs. Distinct failure mode related to load induced edge delamination traces on the glass web is reported. Based on the test results, the distribution of acting strains and stresses within the composite beams is plotted. The formation of inclined cracks on the glass web is justified as the stress trajectories are prone to bend to form a diagonal tension stress state. It is shown from the response of composite beams that the strength and elastic stiffness of composite beams are improved when the adhesives with better mechanical properties are used. Afterwards, it is shown that the strengths of test specimens are greater than these of counterpart glass stabilizing fins or stiffening fins due to the flexibility of adhesive joining. Finally, the test strengths have been evaluated based on the edge delamination traces and the equilibrium of the energy dissipation of proposed mechanism. It is demonstrated that the proposed mechanism in contrast to referred formulae is able to give a better prediction of strength.

Fabrication and mechanical characterization of continuous carbon fiber-reinforced thermoplastic using a preform by three-dimensional printing and via hot-press molding

A new 3D printer equipped novel nozzle structure for continuous carbon fiber-reinforced thermoplastics (C-CFRTP) was developed and the suitable printing conditions were studied. C-CFRTP filament and additional matrix resin were supplied independently using each extruder, which is useful for variety printing and precise form control in 3D printing. To measure the mechanical properties, specimens for tensile strength testing were fabricated using C-CFRTP filament (Vf:50%) without additional matrix resin. The experimental results indicate that the tensile strength and Young’s modulus were approximately 700 MPa and 53 GPa, respectively. The recrystallization effect through annealing after 3D printing yielded no drastic improvement. The mechanical properties were considerably improved by a hot-press treatment after 3D printing. The tensile strength and Young’s modulus increased to approximately 1400 MPa and approximately 90 GPa, respectively. These results suggest that one of the useful applications of C-CFRTP 3D printing technology is preforming of small parts in industrial products.

Short fiber reinforced 3d printed ceramic composite with shear induced alignment.

This paper accounts for utilization of shear induced alignment method during ceramic stereolithography. Lateral oscillation mechanism, combined with 3d printed wall pattern, was employed to generate necessary shear to align fiber in desired direction. First, semicircular channel pattern was printed to assess the effect of difference between wall direction and oscillation direction on the fiber alignment. Then, flexural strength of ceramic matrix was tested with nickel coated carbon fiber and ceramic fiber reinforcements. The results demonstrated that the shear induced alignment further improves the flexural strength compare to randomly distributed samples. Flexural strength of aligned samples with 1.0 wt% carbon fiber loading was improved by ~90% compared to randomly orientated samples and by ~333% compared to unreinforced samples. Finally, fracture surface morphology of the flexural strength test specimens was evaluated. The main fracture mechanism was observed as fiber pull-out.

Investigation of the influence of different surface regularization methods for cylindrical concrete specimens in axial compression tests

ABSTRACT This study was conducted with the aim of evaluating the influence of different methods for end surface preparation of compressive strength test specimens. Four different methods were compared: a mechanical wear method through grinding using a diamond wheel established by NBR 5738; a mechanical wear method using a diamond saw which is established by NM 77; an unbonded system using neoprene pads in metal retainer rings established by C1231 and a bonded capping method with sulfur mortar established by NBR 5738 and by NM 77. To develop this research, 4 concrete mixes were determined with different strength levels, 2 of group 1 and 2 of group 2 strength levels established by NBR 8953. Group 1 consists of classes C20 to C50, 5 in 5MPa, also known as normal strength concrete. Group 2 is comprised of class C55, C60 to C100, 10 in 10 MPa, also known as high strength concrete. Compression tests were carried out at 7 and 28 days for the 4 surface preparation methods. The results of this study indicate that the method established by NBR 5738 is the most effective among the 4 strengths considered, once it presents lower dispersion of values obtained from the tests, measured by the coefficient of variation and, in almost all cases, it demonstrates the highest mean of rupture test. The method described by NBR 5738 achieved the expected strength level in all tests.

Determination of the Effect of Surface Roughness on the Bonding Strength of Wooden Materials

The purpose of this study was to determine the effect of surface roughness on bonding strength in Oriental beech, cherry, Scots pine, and Taurus cedar woods. In conformance with this objective, after planing the wooden materials under different conditions, their surface roughness values were determined in accordance with various standards using scanning equipment. The bonding strength test specimens were prepared using polyvinyl acetate (PVAc) and polyurethane (PUR) adhesives after the wooden materials were separated into three groups of varying surface roughness values, after which bonding strength experiments were carried out. The data obtained from the experiments were evaluated statistically at a 95% level of confidence. According to the test results, the highest bonding strength was obtained in the Oriental beech (9.27 N/mm2), whereas the lowest bonding strength was obtained in the Scots pine (3.65 N/mm2). There was not a statistically significant difference between the bonding strength of the cherry and Oriental beech woods. The PVAc adhesive (7.61 N/mm2) produced more successful results than the PUR adhesive (5.63 N/mm2). Furthermore, it was found that in the specimens with low surface roughness values for each wood type and used adhesives had high bonding strengths.

Improvement in the Bonding of Y-TZP by Room-temperature Ultrasonic HF Etching.

To investigate the effects of room-temperature etching with hydrofluoric acid (HF) in the presence and absence of ultrasonic irradiation on the bonding of yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) to resin. Y-TZP specimens were etched with 40% HF at room temperature for different time periods (2, 5, 10, 15, 30, 60, and 90 min) with and without ultrasonic exposure. The surface roughness, micromorphology, dimensions, and phases of the treated Y-TZP specimens were evaluated by atomic force microscopy (AFM), scanning electron microscopy (SEM), digital caliper measurement, and x-ray diffraction, respectively. The HF etching conditions that resulted in the most drastic Y-TZP surface morphology and highest roughness values were used to prepare specimens for shear bond strength (SBS) testing; the effect of thermocycling on SBS was also examined. Alumina-sandblasted Y-TZP specimens were used as the control. The Y-TZP surfaces etched with HF without ultrasonic exposure for 30, 60, and 90 min and those surfaces ultrasonically etched with HF for 10 and 15 min were severely etched, although their dimensions were not changed by etching. Monoclinic-phase zirconia was observed only in the alumina-sandblasted Y-TZP specimens. Surface roughening from HF etching for 30 min and ultrasonic etching for 10 min resulted in higher mean SBS compared to roughening with alumina sandblasting. Ultrasonic etching with 40% HF at room temperature for 10 min may be used as an alternative roughening method for improving the bonding of Y-TZP.

Effect of interim cement application on bond strength between resin cements and dentin: Immediate and delayed dentin sealing

Statement of problemDespite the advances in materials and techniques, adhesion to dentin is challenging because of the complex composition of dentin’s mineral, organic, and fluid phases. PurposeThe purpose of this in vitro study was to evaluate the bond strength of 2 different resin cements (conventional and self-adhesive) with or without previous dentin sealing and the effect of interim cement. Material and methodsForty-five molars were embedded into acrylic resin blocks and a flat dentin surface was exposed. Twenty teeth (n=5 per group) were treated with the conventional resin cement associated with etch-and-rinse or self-etch adhesive approaches, applied before (immediate dentin sealing) or after (delayed dentin sealing) the application/removal of interim cement. Another 25 teeth (n=5, per group) were treated with self-adhesive resin cement with (self-etch mode [immediate dentin sealing or delayed dentin sealing]) or without adhesive application. Furthermore, in the self-adhesive resin cement group, the application of polyacrylic acid for dentin etching before cementation was evaluated. Composite resin blocks were cemented onto flat, treated dentin surfaces, and the assemblies were sectioned into bar-shaped specimens for microtensile bond strength testing. The data were subjected to 1-way ANOVA followed by the post-hoc Tukey test (α=.05). The failure patterns were classified as cohesive, adhesive, or mixed. ResultsThe application of adhesive before interim cement (immediate dental sealing) promoted the highest values of bond strength for both resin cements (P<.001). For self-adhesive resin cement, polyacrylic acid-enhanced bond strength after the application of interim cement. ConclusionsThe application of dental adhesive immediately after tooth preparation (immediate dentin sealing) and before the use of an interim cement promoted the highest values of bond strength to dentin with the resin cements tested.

An Experimental Study of pH Value and Flexural Strength of Cement Sand Mortar with Surface Untreated Multi-Walled CNTs

Background/Objectives: The paper describes the study carried out on test specimens of cement mortar composite admixed with multi-walled carbon nanotubes (CNTs) in order to investigate the physical property changes under nano-level hydration. Methods/Statistical Analysis: In this study, the standard engineering tests such as pH value identification, flexural strength test and compression strength tests were carried out for both control and test specimens which were cast and cured as per Indian Standard specifications. Test specimens of cement mortar composite consisted of ordinary Portland cement and river sand added with 0.2% (by weight of cement) pristine multi-walled CNTs ultrasonicated but without any surface treatment. Findings: The pH value of ultrasonicated multi-walled CNTs dispersed in de-ionised (DI) water was first determined and found to be 6.85. The pH of control mix without multi-walled CNTs was 12.64 and the pH of test mix with multi-walled CNTs was 12.37. The percentage addition of multi-walled CNTs was very small and hence the reduction in alkalinity was found to be equally small. Flexural strength of test specimens showed 23%, 31.41% and 31.46% increase at 7, 28 and 45 days respectively over control specimens. Compressive strength of test specimens showed 6.1% increase at 28 days over control specimens. Application/Improvements: In view of improvement in flexural strength in mortar, addition of multi-walled CNTs to concrete elements may help in improving their performance under dynamic loading. Further improvements are required to study the effect of an increased percentage addition of multi-walled CNTs without any surface treatment and without any surfactant in cement sand mortar (1:3).

다양한 표면처리에 따른 리튬이온 이차전지용 파우치 필름을 위한 접착성에 관한 연구

Pouch film is manufactured by laminating aluminum foil, polyamide film and polypropylene film with an adhesive or extrusion resin. However, a surface treatment is required for the aluminum because bonding does not occur easily between the aluminum foil and the polymer film. Thus, for this study, surface treatment experiments were performed in order to confirm the effect on adhesion strength. First, a variety of surface treatment solutions were coated on aluminum foil, and contact angle and surface morphology analysis was carried out for the surface-treated aluminum. For lamination of the surface-treated aluminum foil with polyamide film, a polyurethane base adhesive was prepared for the adhesive strength test specimens. The adhesive strength between the aluminum foil and the polyamide film of the resulting specimens was measured (UTM). With such an experiment, it was possible to evaluate the effect on adhesive strength of the various surface treatments.