Papers by Keyword: Flexure Strength

Abstract: The paper deals with the approximation of the time evolution of the strengths of selected alkali-activated aluminosilicate (AAAS) composites based on ceramic precursors. Composites made of brick dust as a precursor and an alkaline activator with a silicate modulus of M_s = 0.8, 1.0, 1.2, 1.4, and 1.6 were investigated. The filler consisted of standard quartz sand in one case, and crushed brick in the other. The test specimens had nominal dimensions of 40 × 40 × 160 mm and were tested in three-point bending after 7, 28, 90, and 300 days of maturation. From each composite, 3 specimens were tested and the compressive strength was determined from the 6 specimen parts that remained after the bending tests. The obtained flexural and compressive strength values for the abovementioned 4 composite ages were approximated by the exponential function , where the coefficient a represents a horizontal asymptote to the approximation curve, i.e. the theoretical strength of the composite at time t = ∞; the exponential term of the approximation with the coefficients b and c expresses the degree of the time-dependent change of the respective compressive strength in the interval t = (0, ∞). The approximation was performed with the least squares method using genetic algorithms implemented in the Java GA package with open source code.

Abstract: Banana fiber is agricultural waste that can be obtained after harvesting the fruit with no additional cost. Banana fiber has major drawbacks in composite product such as low interfacial bond strength between fiber and matrix as comparison with synthetic fiber. The aim of this research is to investigate the effect of alkaline concentration treatment conditions on tensile strength and flexural strength properties of banana fiber reinforced polyester resin composite. Banana fiber was treated using sodium hydroxide (NaOH) treatment. There are four variations of NaOH concentration treatment, 0%, 5%, 10% and 15% for 1 hour immersion time at room temperature. Hand lay-up technique was used in composite fabrication with 40% fiber volume fraction at random orientation of banana fiber. Based on this research result can be concluded that composite with NaOH treatment has a better tensile strength and flexural strength if compared with untreated fiber. Banana fiber composite treated with 5% NaOH concentration show the highest tensile and elasticity modulus, and also flexural strength and flexural modulus better compare the other treatment. Banana fiber composite specimens on macro picture observation show that the untreated fiber has a lot of fiber pull-out, it is occur the weak interfacial bond between matix and fiber. On the other hand, the treated banana fiber composite shows a slight fiber pull out, because composite has high interfacial bond between matrix and fiber.

Abstract: In this study, an experimental investigation was conducted in order to determine the effect of different adhesive thickness (i.e., 0.1, 0.5, 0.7 and 1 mm) on strength of ductile adhesive joint. The study scope covers both experiment and analysis. In particular, two different types of material, aluminum and stainless steel as adherents were used and joined by using a specific adhesive jig. By using universal tensile machine (UTM), three-point-bending (3PB) test was conducted. To obtain the result from the experiment, continuous load is applied to the adhesive until the adhesive become fracture. The result obtained has enabled the clarification of failure behavior mechanisms and characteristics of adhesive bonding.

Abstract: Cement-Treated Base (CTB) is a non-conventional method used in road bases materials to improve its engineering properties due to the hardening of cement when moisture is present and extends the period of curing times. This study investigates the effects of cement additive on properties of base layer using laboratory mechanistic evaluation of stabilized soil mixtures. Laboratory tests conducted were Unconfined Compressive Strength (UCS), Indirect Tension test for Resilient Modulus (ITRM) and Flexure Strength (FS) tests. The results revealed that by adding Portland cement, the mechanical properties of the mixture have improved where the UCS is found to be an important quality indicator. In addition, the variables that influenced these tests, which are cement content, curing time, moisture content, and dry density, play important role to determine the performance of CTB. This paper presents the finding of a correlation conducted to analyse the influences of these variables using regression and ANOVA to establish significant models with the aim of predicting the strength base on mixture parameters. Keywords: Cement-Treated Base, Unconfined Compressive Strength, Indirect Tension test for Resilient Modulus, Flexure Strength, Moisture Content, Dry Density, Regression Analysis.

Abstract: In order to investigate flexure properties of high-strength corrugated composite paperboard(HCCP), applying the method of flexure property test for sandwich structure, four kinds of thickness paperboard –10,15,20 and 30mm– were tested according to longitudinal and transverse direction respectively, then the curve of flexure load – deflection was analyzed, the paper focused on the relationship between flexure yield load, flexure strength of face sheet, shear strength of core and thickness and direction of paperboard. The investigation has a strong significance for HCCP’s application in practice.

Abstract: Objective. To investigate the flexure strengths and elastic modulus of four types of dental fiber posts. Methods. The flexure strengths of ParaPost Taper Lux, Tenax Fiber White, Luxa Post and Rebilda Post fiber post were measured. The rupture modes were analyzed with SEM. Results. There was no significant difference between ParaPost Taper Lux (591.47±35.15MPa) and Rebilda Post (614.67±58.36MPa) in flexure strength (P>0.05), and Tenax Fiber White (846.62±71.15MPa) had significantly higher flexure strength than the other groups. There was no significant difference between Tenax Fiber White (23.93±2.14GPa) and Luxa Post (22.67±1.39GPa) in elastic modulus (P>0.05), and Tenax Fiber White and Luxa Post had significantly lower elastic modulus than other groups. It could be observed by transverse SEM that the combine of fiber and resin was even and compact and plenty of resin fragment adhered to the surface of fiber in Tenax Fiber White group, multitudinous cracks were observed by lengthwise SEM. Conclusion. The flexural properties and rupture modes of four kinds of dental fiber posts were significantly different.

Abstract: Sintering is a key step in the metal injection moulding (MIM) process, which affects the mechanical properties of the sintered part. The mechanical property of the sintered compact is resulted from tremendous sintered part densification. The paper presents an optimisation of the sintering parameter for the best flexure strength of the fine SS316L water atomised powder compact. The L9 (34) orthogonal array is used in the study and four replication of the flexure strength has been recorded at each experiment trial. The analysis of variance (ANOVA) signifies the sintering variables are highly significant to the flexure strength, α = 0.005. The study demonstrates that the cooling rate is the most influential variable that contributes to the best flexure strength, followed by heating rate, dwell time and sintering temperature.

Abstract: A series of experiment based on different mixing time were carried out to investigate the effect of mixing time on slump, modified VC value and strength properties of concrete in different consistency. The flexural strength, compressive strength on the conditions of highly stiff s, stiff and plastic system was studied. The optimized mixing time was determined and its reason was analyzed. The examination result show that the highly stiff concrete have the best performance when the mixing time is at about 120s, the stiff system is at 60s, the plastic system is at 30s.

Abstract: The effect of Cs⁺ ion and Rb⁺ ion in the molten salt of different proportion on the single panel fire-resistant glass is discussed in this paper. The single panel fire-resistant glass was prepared by the method of ion-exchange, with proper amount of additives and adding KNO₃ and CsNO₃ , KNO₃ and RbNO₃ as the main part of molten salt. The proportion of the molten salt was changed separately, a contrast test was performed to measure the flexure strength. The results indicated that the flexure strength of the single panel fire-resistant glass increased firstly and then stabilized as the ratios of w(CsNO₃)/w(KNO₃) and w(CsNO₃)/w(RbNO₃) increased respectively. With the ratio of w(CsNO₃)/w(KNO₃) =1.5%, the mechanical property of the single panel fire-resistant glass was proper and the maximum flexure strength was 274 MPa. In the case of RbNO₃, the flexure strength of single panel fire-resistant was 244 MPa with the ratio of w(CsNO₃)/w(KNO₃) = 0.3%. According to the research, it is found that the method of ion-exchange of Cs+ and Rb+ into plain glass to prepare single panel fire-resistant glass is feasible, the sample melted under the condition of 1 hour and 780 without any trace of thermal explosion.

Abstract: SiO2 coatings and double layer films of SiO2/Si3N4 have been designed and prepared on sapphire (α-Al2O3) by radio frequency magnetron reactive sputtering in order to improve the optical and mechanical properties of infrared windows of sapphire. The transmission of the coated and uncoated sapphire in the wavelength range from 2.5 to 6.7um was determined. Surface morphology and roughness of coated and uncoated sapphire have been measured using a talysurf. The flexure strength of coated and uncoated sapphire samples has been studied by 3-point bending tests at room temperature and high temperatures. The results show that the coatings can improve the surface morphology and reduce the surface roughness of sapphire substrate. What’s more, the designed single layer of SiO2 film and two-layer of SiO2/Si3N4 films can both increase the transmission of sapphire in mid-wave IR and strengthen sapphire at high temperatures. Coated sapphire transmits over 95% at wavelength from 3 to 5um for the two designs. Flexure tests reveal that SiO2 coatings and SiO2/Si3N4 films increase the strength of c-axis sapphire by a factor of about 1.5 and 1.4, respectively, at 800°C.