Linear-nonlinear stiffness responses of carbon fiber-reinforced polymer composite materials and structures: a numerical study

The stiffness response or load-deformation/displacement behavior is the most important mechanical behavior that frequently being utilized for validation of the mathematical-physical models representing the mechanical behavior of solid objects in numerical method, compared to actual experimental data. This numerical study aims to investigate the linear-nonlinear stiffness behavior of carbon fiber-reinforced polymer (CFRP) composites at material and structural levels, and its dependency to the sets of individual/group elastic and damage model parameters. In this regard, a validated constitutive damage model, elastic-damage properties as reference data, and simulation process, that account for elastic, yielding, and damage evolution, are considered in the finite element model development process. The linear-nonlinear stiffness responses of four cases are examined, including a unidirectional CFRP composite laminate (material level) under tensile load, and also three multidirectional composite structures under flexural loads. The result indicated a direct dependency of the stiffness response at the material level to the elastic properties. However, the stiffness behavior of the composite structures depends both on the structural configuration, geometry, lay-ups as well as the mechanical properties of the CFRP composite. The value of maximum reaction force and displacement of the composite structures, as well as the nonlinear response of the structures are highly dependent not only to the mechanical properties, but also to the geometry and the configuration of the structures

Design and fabrication of natural woven fabric reinforced epoxy composite for household telephone stand

In the recent era there has been an increasing interest in composite materials for its applications in the field of aerospace, sports, industries, medical, and in many other fields of engineering including household furniture. This paper deals with the design and fabrication of banana woven fabric reinforcement epoxy composite for household telephone stand. A systematic approach of total design process is presented for better understanding of the best design concept for the product. The fabrication process of composite telephone stand using banana woven fabric is also described in this paper

Mechanical and thermal properties of sugar palm fiber reinforced thermoplastic polyurethane composites: effect of silane treatment and fiber loading

The aim of the present study was to develop sugar palm fiber (SPF) reinforced thermoplastic polyurethane (TPU) composites and to investigate the effects of fiber surface modification by 2% silane treatment and fiber loading (0, 10, 20, 30, 40 and 50 wt%) on the mechanical and thermal properties of the obtained composites. Surface treatment was employed to improve the fiber-matrix interface, which was expected to boost the mechanical strength of the composites, in terms of tensile, flexural and impact properties. Thermal properties were also investigated by thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) to assess the thermal stability of the developed composites. Furthermore, scanning electron microscopy (SEM) was used to study the tensile fracture samples of composites with a view towards evaluating the effects of fiber surface treatments on the fiber/matrix interfacial bonding. The findings of this study reveal that the silane treatment has determined good bonding and linkage of the cellulose fiber to the TPU matrix, hence contributing to enhanced mechanical and thermal properties of the composites. The composite formulation with 40 wt% sugar palm fiber loading showed optimum values such as 17.22 MPa for tensile, 13.96 MPa for flexural, and 15.47 kJ/m2 for impact strength. Moreover, the formulations with higher fiber content exhibited satisfactory values of storage modulus and thermal degradation, while their good interfacial adhesion was evidenced by SEM images

Mechanical performance of roselle/sugar palm fiber hybrid reinforced polyurethane composites

The effect of sugar palm fiber (SPF) loading was studied relative to the mechanical properties of roselle (RF)/SPF/thermoplastic polyurethane (TPU) hybrid composites. RF/SPF/TPU hybrid composites were fabricated at different weight ratios (100:0, 75:25, 50:50, 25:75, and 0:100) by melt mixing and hot compression. The mechanical (tensile, flexural, and impact test) and morphological properties of tensile fractured samples were examined using a universal testing machine, impact machine, and scanning electron microscope. It was found that the hybridization of RF/SPF increased its impact strength corresponding to the increases in the SPF content of the composites. The tensile and flexural properties of the hybrid composites decreased due to poor interfacial bonding between the fiber and matrix. Scanning electron micrographs of the tensile fractured surface of the RF/SPF hybrid composites revealed fiber pullouts and poor adhesion bonding. In conclusion, the hybridization of SPF with RF/TPU composites enhanced its impact strength while decreasing the tensile and flexural strength

Mechanical properties study of pseudo-stem banana fiber reinforced epoxy composite

The source of banana fiber is the waste banana trunks or stems which are abundant in many places in the world. Therefore, composites of high–strength pseudo-stem banana woven fabric reinforcement polymer can be used in a broad range of applications. The objective of this paper is to study the tensile, flexural, and impact properties of pseudostem banana fiber reinforced epoxy composites

Development and characterization of sugar palm starch and poly(lactic acid) bilayer films

The development and characterization of environmentally friendly bilayer films from sugar palm starch (SPS) and poly(lactic acid) (PLA) were conducted in this study. The SPS-PLA bilayer films and their individual components were characterized for their physical, mechanical, thermal and water barrier properties. Addition of 50% PLA layer onto 50% SPS layer (SPS50-PLA50) increased the tensile strength of neat SPS film from 7.74 to 13.65MPa but reduced their elongation at break from 46.66 to 15.53%. The incorporation of PLA layer significantly reduced the water vapor permeability as well as the water uptake and solubility of bilayer films which was attributed to the hydrophobic characteristic of the PLA layer. Furthermore, scanning electron microscopy (SEM) image of SPS50-PLA50 revealed lack of strong interfacial adhesion between the SPS and PLA. Overall, the incorporation of PLA layer onto SPS films enhances the suitability of SPS based films for food packaging

Effect of seaweed on physical properties of thermoplastic sugar palm starch/agar composites

The aim of this paper is to investigate the physical properties of thermoplastic sugar palm starch/agar (TPSA) blend when incorporated with seaweed. The ratio of starch, agar, and glycerol for TPSA was maintained at 70:30:30. Seaweed with various contents (10, 20, 30, and 40 wt.%) were mixed with TPSA matrix via melt mixing before compression were molded into 3 mm plate at 140oC for 10 minutes. The prepared laminates were characterized for moisture absorption, water absorption, thickness swelling, water solubility, and density. The results showed that increasing seaweed loading from 0 to 40 wt% has led to a drop in moisture content from 6.50 to 4.96% and 9% reduction of the density. TPSA matrix showed 52.5% water uptake and 32.3% swelling whereas TPSA/seaweed composites (40 wt% loading) showed 97% water uptake and 74.8% swelling respectively. Higher water solubility was also shown by TPSA/seaweed composites (57 wt%) compared to that of the TPSA matrix (26 wt%). After 16 days of storage, the equilibrium moisture content for TPSA and TPSA/seaweed (40 wt% loading) were 23.2 and 25.2% respectively. In conclusion, TPSA/seaweed composites show good environmental friendly characteristics as a renewable material. In future, the properties of this material can be further improved by hybridization with more hydrophobic fillers for better resistance against water

Characterisation of cassava biopolymers and the determination of their optimum processing temperatures

This work reports the characterisation of cassava biopolymers. Moreover, the effects of processing temperature on the tensile properties and phase morphology of cassava biopolymers were investigated. Eight diff erent temperatures were selected as processing temperatures in sample preparation of the cassava biopolymers. Variance analysis justifies that 165 and 170°C are the optimum processing temperatures in producing maximum tensile properties. The present study reveals that the range of processing temperatures for cassava biopolymer was relatively lower as compared to the majority of the petroleum-based polymer. However, its low processing temperature makes this biopolymer has enormous potential in the development of fully biodegradable composites

Characteristics of thermoplastic sugar palm Starch/Agar blend: Thermal, tensile, and physical properties

The aim of this work is to study the behavior of biodegradable sugar palm starch (SPS) based thermoplastic containing agar in the range of 10–40 wt%. The thermoplastics were melt-mixed and then hot pressed at 140◦C for 10 min. SEM investigation showed good miscibility between SPS and agar. FT-IR analysis confirmed that SPS and agar were compatible and inter-molecular hydrogen bonds existed between them. Incorporation of agar increased the thermoplastic starch tensile properties (Young’s modulus and tensile strength). The thermal stability and moisture uptake increased with increasing agar content. The present work shows that starch-based thermoplastics with 30 wt% agar content have the highest tensile strength. Higher content of agar (40 wt%) resulted to more rough cleavage fracture and slight decrease in the tensile strength. In conclusion, the addition of agar improved the thermal and tensile properties of thermoplastic SPS which widened the potential application of this eco-friendly material. The most promising applications for this eco-friendly material are short-life products such as packaging, container, tray, et

Characteristics of Eucheuma cottonii waste from East Malaysia: physical, thermal and chemical composition

The aim of this paper was to examine the characteristics of Eucheuma cottonii waste in order to analyse its potential as renewable material. The morphology of Eucheuma cottonii (raw and wastes) was investigated through scanning electron microscopy (SEM), the thermal behaviour through thermogravimetric analysis (TGA) and the physical properties through FT-IR, XRD, gas pycnometer, particle size analyser, water absorption and moisture content analysis. The chemical compositions were determined by using acid detergent fibre (ADF), neutral detergent fibre (NDF) and acid detergent lignin (ADL) analysis. It was found that Eucheuma cottonii wastes have better thermal stability, higher crude fibre content, lower moisture content and similar density to the raw Eucheuma cottonii, which suggests that these biomass wastes have good potential as renewable filler material