Annual Book Of Astm Standards

Search for novel energy-efficient, eco-friendly, and time-saving manufacturing techniques has gained momentum in the recent times. Polymer composites have been increasingly adapted for variety of industrial applications, however, their efficient processing remains challenging. Microwave curing technique has been employed to process thermoset-based composites since 1980, however, processing of thermoplastic-based composites with natural-fibers as reinforcement, calls for additional data and hence investigations. The current work presents an overview of the basics of microwave heating and the physics behind the microwave processing of polymer composites. A state-of-the-art on microwave processing of thermoset and thermoplastic-based composites and developments in microwave joining has been reviewed. The major constraints in adopting microwave technology for curing composites at the industry scale are highlighted. The article also highlights the challenges during microwave processing of sustainable thermoplastic-based polymer composites. Future scope of work to 3D print the polymer matrix composite parts, through microwave scanning route has been indicated. 

Processing of polymer matrix composites using microwave energy: A review

Natural fibre-reinforced composites have attracted a great deal of attention by the automotive industry mainly due to their sustainable characteristics and low cost. The use of sustainable composites is expected to continuously increase in this area as the cost and weight of vehicles could be partially reduced by replacing glass fibre composites and aluminium with natural fibre composites. Adhesive bonding is the preferred joining method for composites and is increasingly used in the automotive industry. However, the literature on natural fibre reinforced polymer composite adhesive joints is scarce and needs further investigation. The main objective of this study was to investigate experimentally adhesively bonded joints made of natural, synthetic and interlaminar hybrid fibre-reinforced polymer composites. The effect of the number of the interlaminar synthetic layers required in order to match the bonded joint efficiency of a fully synthetic GFRP bonded joint was studied. It was found that the failure load of the hybrid jute/glass adherend joints increased by increasing the number of external synthetic layers (i.e. the failure load of hybrid 3-layer joint increased by 28.6% compared to hybrid 2-layer joint) and reached the pure synthetic adherends joints efficiency due to the optimum compromise between the adherend material property (i.e. stiffness and strength) and a diminished bondline peel stress state.

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Adhesively bonded joints of jute, glass and hybrid jute/glass fibre-reinforced polymer composites for automotive industry

ABSTRACT The recent global pandemic has created a grave concern and awareness about the importance of the environment. The researchers/engineers/scientists are now focusing their efforts on the development of technologies that can ensure the sustainable growth of communities. Materials are at the core of every technological advancement. Natural fiber-based composites are a class of sustainable materials being used in diverse engineering applications, ranging from automotive to household goods. The processing methods, such as hand lay-up, injection, and compression molding are used extensively to fabricate simple composite parts. However, for complex/intricate product designs, the parts/components are made independently and these are assembled to get the final product. Joining thus becomes an inevitable process ensuring the assembly of parts/components. In the current experimental investigation, the hot-plate welding (HPW) behavior of sisal/jute fiber (both woven and short) reinforced polypropylene (PP) composite specimens fabricated using direct compression molding(DCM) and Extrusion injection molding (EIM) have been analyzed. The process parameters optimization has been achieved using the Taguchi experimental design approach. The hot plate welded joints of jute/sisal/PP composites were further investigated on the basis of their flexural and tensile properties. The failed joint specimens were characterized using TGA and XRD characterization techniques to analyze any changes occurred in their thermal degradation and crystalline behavior during welding process. The failure mechanisms of the joints have been thoroughly analyzed using SEM micrographs.

Hot-Plate welding behavior of Sisal and Jute Polypropylene composites

ABSTRACT In this study, different combinations of Hemp, Bamboo and Coir fiber are considered as reinforcement materials, while AW106 epoxy resin and HV953 are used as hardeners. The composite lamina was prepared and tested using the hand layup technique with short and random fibers. The tensile and compressive test performed for the analysis of mechanical properties shows that 15% hemp fiber composite is better than bamboo and coir fiber composite. With the increase in fiber volume fraction mechanical properties increases up to a certain limit and a further increase in fiber volume ratio shows adverse effect. Numerical modeling of 15% hemp fiber composite, 15% bamboo fiber composite and 15% coir fiber composite has been done for the calculation of natural frequency and damping factor of natural fiber composite. Numerical modelling was performed using ANSYS 2021 R1 and the specimen was considered in the form of a cantilever beam with a size 200 mm × 20 mm × 4 mm. The damping factor was calculated with the help of the half-power bandwidth method. Numerical analysis reveals that natural frequency and damping values of hemp fiber composite are better than bamboo and coir fiber composite. The worst results were obtained for coir fiber composite. The nondimensional frequency response of hemp fiber composite is better than bamboo and coir fiber composite.

Experimental and numerical analysis of different natural fiber polymer composite

Growing awareness about sustainable development and the environmental problems involved in using nonbiodegradable materials has motivated the research community to develop environment-friendly mate...

Adhesive joining of sisal/jute/hybrid composites with drilled holes in lap area:

The natural fiber-based polymeric composites are being used extensively in various engineering applications, especially in the non-structural parts and components. Although, a large number of prima...

Joining Behavior of Jute/Sisal Fibers Based Epoxy Laminates Using Different Joint Configurations

Polymer matrix composites (PMCs) fabricated using natural fibers as reinforcement are preferred in many engineering applications including marine, automotive and aerospace industry due to their eco-friendly nature. The components fabricated using natural fiber-based PMCs often need the joining of different sections to fabricate an industrial component. Usually, adhesive joining is used to join the thermoplastic-based composite parts. However, achieving adequate mechanical strength is challenging due to moisture entrapment in between the joining adherents and uneven transfer of heat, which causes the burning of matrix material and damage to the natural fibers. In the present work, PMCs were developed through the compression molding technique using jute fibers as reinforcement and polypropylene (PP) as matrix material. Subsequently, developed composite samples were lap joined using microwave energy at 2.45 GHz and 900 W. A special fixture was designed and developed to concentrate microwave energy around the joining area. The study demonstrates that microwave energy provides rapid heating (75 s) for joining on the samples. Using the developed fixture, the tensile test results for fabricated composite joints revealed that the maximum joint efficiency was 81% with the maximum tensile strength of 21 MPa. The present study indicates that microwave energy can be further exploited as a potential rapid joining process for polymers in the future.

Design of a Customized Fixture for Joining Jute Fiber-Based Composites Using Microwave Energy

Fiber Reinforced Plastics (FRPs) are being used extensively in various engineering applications ranging from aerospace to sports goods. In recent years, environmental concerns and awareness have challenged engineers and scientists to develop materials that are sustainable and have the potential to replace the traditional FRPs. Natural fiber-based polymeric composites (NFRPC) are now being investigated and proposed worldwide for various applications, especially automotive components and domestic products. To ensure the fabrication of highly intricate composite products, joining becomes inevitable. Adhesive joining is the most commonly employed fabrication process for composite joints. However, the performance of adhesive joints is susceptible to their exposure to different environmental conditions. In the present experimental investigation, the joint strength of woven fiber mat (sisal, jute, and hybrid) reinforced epoxy composites has been investigated in Three Months Cyclic Temperature Variation, and the natural fiber reinforced epoxy adherends have been successfully joined using adhesive along with two/four holes in the overlap area. The performance of the adhesive joints has been investigated under a daily thermal cycle from 5 °C (12 hrs.) to 40 °C (12 hrs.), for three consecutive months. It was observed that the hybrid composites recorded better-joining performance. Moreover, the Field Emission Scanning Electron Microscopy (FE-SEM) has been used to understand the failure mechanisms during tensile testing of adhesively bonded natural fiber-reinforced composite laminates. It has been found that the exposure of the composite joints to a variable temperature during the day has a significant effect on their tensile behavior. The major factors affecting the performance of joints exposed to the thermal cycle are; the type of natural fiber, the number of holes in the adherend area, and the duration of exposure. The results are important for the designers of composite structures with adhesively bonded joints. 

Kassahun Gashu Melese

Papers

Adhesive joining of sisal/jute/hybrid composites with drilled holes in lap area:

Joining Behavior of Jute/Sisal Fibers Based Epoxy Laminates Using Different Joint Configurations

Hot-Plate welding behavior of Sisal and Jute Polypropylene composites

Design of a Customized Fixture for Joining Jute Fiber-Based Composites Using Microwave Energy

Adhesive behavior of sisal and jute composite exposed to three months cyclic temperature variation