Papers by Keyword: Flexural Strain

Abstract: The objective of this research is to investigate how the quantity of laminate layers impacts the Ramie-Eglass fiber hybrid composite utilized in the Jaloe Kayoh material, specifically concerning mechanical properties such as tensile strength and flexural properties. In this research, the authors conducted tensile and flexural testing on composites with varying quantities of laminate layers. The research findings indicate that incorporating a laminate layer into the hybrid composite positively affects its mechanical properties. The composites with 5 laminate layers had the maximum tensile strength, measuring approximately 59.79 MPa, and the highest tensile modulus, measuring around 3.15 GPa. The results suggest that adding a suitable number of laminate layers can enhance the composite's resistance to tensile stress and preserve its structural stiffness. Furthermore, the composite consisting of 6 laminate layers demonstrated the largest elongation at break, measuring at 2.04%. This result suggests that the material has a commendable ability to withstand strain before reaching its breaking point. For flexural properties, the configuration with 3 layers of lamina shows the most optimal results with flexural strength of around 161.11 MPa, flexural strain of around 0.021, and flexural modulus of around 3.47 GPa. Therefore, this configuration is recommended as the most optimal to withstand flexural stress on Jaloe Kayoh. This study offers valuable insights into the correlation between the quantity of laminate layers and the mechanical properties of Ramie-Eglass fiber hybrid composites. These insights can be utilized to create advanced composite materials for Jaloe Kayoh boats.

Abstract: Positron Annihilation Lifetime Spectroscopy (PALS) is used to study the nanoporosity and fractional free volume in Ultra High Molecular Weight Polyethylene (UHMWPE) and composites with the addition of Martian Regolith (UHMWPE-MR) as-made and irradiated with ⁵⁶Fe heavy ions at an energy of 600 MeV/u to three different doses (10, 32, 64 Gy). The positron lifetime spectra were obtained using ²²Na positron source and the spectra were analyzed to two lifetime components using POSFIT program. First short lifetime component around 0.28 ns is related to positron annihilation in material including vacancy defects and the second long lived component around 1.7 ns is due to Positronium formation in free volume pores. UHMWPE-MR composites were shown to be less porous with much lower nanopores concentration compared to the UHMWPE polymer. The average size of the nanopores is around 0.5 nm (obtained from a simple model). Larger variations in positron lifetime parameters are observed with increasing irradiation dose for UHMWPE polymer compared to UHMWPE+MR composites. The 3-point bend test results also showed larger variations with increasing irradiation dose for the UHMWPE polymer. The variations in PALS parameters may indicate an increasing competition between two processes at higher irradiation doses: 1) vacancy defects aggregation and 2) escape of vacancy defects as the local temperature increases at higher doses resulting in increased vacancy defects mobility. Present results clearly indicate a qualitative inverse relationship between nanoscale porosity measured by positron life time and mechanical properties of UHMWPE and its composite with MR.

Abstract: The prestressed concrete beam with pretensioned bent-up tendons combines many advantages of the straight-line pretensioned prestressed beams and the curvilinear posttensioned beams. To improve its application in bridges, long-term deformation should be exactly predicted and controlled. Three prestressed concrete beams with pretensioned bent-up tendons XPB1,XPB2, XPB3 were fabricated, and XPB1 and XPB3 were put in standard curing room, but XPB2 were put in outdoor environment. All the experimental beams were simple supported under long-term loads. Their deformation such as creep strain and long-term deflection in mid-span section were observed about 600 days. By analyzing the influence factor and time-history law of creep coefficient and long-term coefficient, creep coefficient equation of the test beams was fitted and compared with the code model such as ACI209R-92, CEB-FIP MC90 and 86 model proposed by China Academy of Building Research, and the ±10% margin error of this model was pointed out. All these results may offer the initial value of long-term deformation of the prestressed concrete beams with pretensioned bent-up tendons.

Abstract: This study investigates the effectiveness of the damage detection methods depending on the data measured by strain and deflection sensors. The experimental work considers the damage detection by measured data only without the baseline data of intact structure. It is shown that the strain sensor cannot indicate the damage if the sensor doesn’t locate at the damage. But the deflection sensor provides the information on the damage from the deflected curve by collected data. The results are illustrated in experimental work.

Abstract: Epoxy resin was filled with glass powder with a view to increasing strength of the composite for structural applications by a research Centre on composites, University of Southern Queensland (USQ). In order to reduce costs, the Centre wishes to fill as much glass powder as possible subject to maintaining sufficient strength of the composites in structural applications. This project varies the percentage by weight of the glass powder in the composites which are then subjected to flexural tests. The results show that composite with 25 % by weight of the glass powder produces the highest flexural strength and Young’s modulus combined with a reasonable fluidity for casting; the highest flexural strain was achieved when the percentage by weight of glass powder is 10 %.

Abstract: Vinyl ester resin was filled with of glass powder with a view to increasing the flexural strength of the composites for civil and structural applications by a research Centre on composites, University of Southern Queensland (USQ). In order to reduce costs, the Centre wishes to fill as much glass powder as possible to the resin subject to maintaining sufficient strength of the composites in civil and structural applications. This project varies the percentage by weight of the glass powder in the composites, which are then subjected to flexural tests. The flexural strength and strain of the glass powder filled vinyl ester composites decreased with increasing filler content but the flexural modulus was highest at 20 w/t % of glass powder. Scanning Electron Microscope (SEM) was used to analyze the fractured samples and it was found that the fractured surfaces examined were correlated with the flexural properties.