Investigation of Mechanical Properties of Banana-Glass Fiber Reinforced Hybrid Composites

Banana stems are very cheap and abundant in nature which can be used to extract fiber. In this paper, banana fiber is used as a reinforcement and epoxy as a matrix to manufacture banana fiber-reinforced epoxy composite. Glass fiber mat, and roving are also used as reinforcement along with banana fiber to manufacture hybrid composites. The objective of this paper is to compare the mechanical properties of hybrid composites with that of pure banana fiber-reinforced composites. The hand lay-up method is used to manufacture all the composites, and tensile and flexural properties are investigated according to the corresponding ASTM standard. It is found that the tensile and flexural strength of banana and glass fiber roving hybrid composites are much higher compared to pure banana fiber-reinforced epoxy composites which make this hybrid composite suitable for low strength application.

Comparison of polymerization stresses of dental resin composites evaluated by two indentation fracture methods

BACKGROUND: Polymerization stress is a major problem in dental resin composite restorations. Two indentation fracture methods can be applied to evaluate the stress, however, they often calculate different values. OBJECTIVE: To compare polymerization stresses of dental composites determined by the two methods. METHODS: Glass disks with a central hole were used. Two indentation fracture methods (Methods 1 and 2) were employed to determine the polymerization stresses of low-shrinkage and bulk-fill composites. Method 1: Cracks were made in the glass surface at 300 μm from the hole. The hole was filled with the composite. Polymerization stresses at 30 min after filling were calculated from the lengths of crack extension. Method 2: The hole was filled with the composite. Cracks were introduced in the glass at 1,000 μm from the hole at 30 min after the polymerization and the stresses were calculated from the crack lengths. Stresses at composite-glass bonded interface were calculated from the stress values obtained by the two methods. RESULTS: The bulk-fill composite generated the smallest interfacial stress, and Method 1 revealed lower values than Method 2. CONCLUSIONS: The composites yielded relatively small stresses. Method 1 calculated smaller stress values, possibly affected by the lower threshold stress intensity factor.

ADDITION OF FLY ASH TO THE FIBER COMPOSITE GLASS ON COMPOSITE FUEL RESISTANCE PROPERTIES

The process of making composites into several main stages, namely preparation of tools, cutting of specimens. Then the base (glass) is cleaned and coated with molding wax and PVA. Mix the resin with the addition of variations of fly ash 0%, 10%, 20% and 30%. Next, apply resin and glass fiber to the base (glass) for up to 3 layers then press it. After 12 hours remove the specimen and cut it to size

Adaptive Powell’s Identification of Elastic Constants of Composite Glass Girder with Layered Shell Element Theory

For the composite glass box girder, the generalized Bayesian objective function of elastic constants of the structure was derived based on layered shell element theory. Mechanical performances of the composite glass box girder were solved by layered shell element method. Combined with quadratic parabolic interpolation search scheme of optimized step length, the adaptive Powell’s optimization theory was taken to complete the stochastic identification of elastic constants of composite glass box girder. Then the adaptive Powell’s identification steps of elastic constants of the structure were presented in detail and the adaptive Powell’s identification procedure was accomplished. From some classic examples, it is finally achieved that the adaptive Powell’s identification of elastic constants of composite glass box girder has perfect convergence and numerical stability, which testifies that the adaptive Powell’s identification theory of elastic constants of composite glass box girder is correct and reliable. The stochastic characteristics of systematic responses and elastic constants are well deliberated in generalized Bayesian objective function. And in iterative processes, the adaptive Powell’s identification is irrelevant with the complicated partial differentiation of the systematic responses from the layered shell element model to the elastic constants, which proves high computation efficiency.

Quasi-static and dynamic mechanical thermal performance of date palm/glass fiber hybrid composites

The present work reports an experimental study on the thermal and mechanical properties of hybrid composites obtained from Petiole Date Palm Fiber (PDPF)/Glass fiber (GF) as reinforcement and vinylester resin (VE). In order to improve the fiber/matrix adhesion, palm fibers were alkali treated with 5% NaOH solution for 24 h–72h. SEM and ATR-FTIR analysis revealed that the 48 h treatment of PDFP with NaOH solution led to rough fiber surface. Vacuum assisted resin transfer molding (VARTM) system was used to produce four hybrid composites (30PDPF/0GF, 20PDPF/10GF, 10PDPF/20GF and 0PDPF/30GF) where the weight ratio of total fiber reinforcement was kept 30%. The treated palm fibers were arranged as a nonwoven mat and placed between woven glass fabrics. Tensile, flexural, dynamic mechanical thermal analysis (DMTA), and thermogravimetric (TGA) were carried out to evaluate the performance of the hybrid composites. The flexural strength and modulus for pure PDPF composite were found to be 60 MPa and 3.87 GPa respectively. Addition of 20%wt glass fiber led an increase in the thermal stability and an enhancement in the tensile and flexural strength by 71.72% and 74.51%, respectively compared to pure PDPF composite. However, the incorporation of 10% of PDPF increases the damping factor from 0.2 for the composite glass/VE to 0.54 for the hybrid 10PDPF/20GF. According to findings of this study, PDPF based composites can be used as non-structural parts in automotive and boat industries.

COMPARATIVE EVALUATION OF RESTORATIVE TREATMENTS ON NON-CARIOUS CERVICAL LESIONS OF COMPOSITE AND GLASS IONOMER CEMENT

Background: Composite and Glass ionomer cement (GIC) are common restorative materials of non carious cervical lesions (NCCLs), which effects are controverisial. The aim of the present study was to compare the result of restorations on NCCLs between Composite and GIC. Materials and Methods: follow-up clinical trial with split-mouth design. Thirty-six patients with 96 NCCLs were divided into 2 groups (n=48/group): Group 1 restored by Composite, Group 2 restored by GIC. The restorations were evaluated at baseline, 1 and 3 months for pulpal sensitivity, restoration morphology and overall success grade. Results: GIC restorations gained 100% Good results for all parameters at 3 time points. Composite showed 87.5%, 93.8% and 97.9% Good results at baseline, 1 and 3 months, sequentially. At 3 weeks recall, 1 Composite restorations (2.1%) showed Moderate results of Retention and 2 Composite restorations (4.2%) changed colour. Conclusions: There was no statistically significant difference seen among the three groups for 3 parameters. Key words: non-carious cervical lesion, Composite, Glass ionomer cement