As molded and fibrous skeleton showing how fine features such as a pin boss are maintained due to the skeletal network of the long fibers long glass fiber in PES resin. As seen, in Figure 8, the fibers are long enough to form a skeleton network and retain the shape of the molded part. The fiber-matrix interface is less open to designing, since the coupling agent in the fiber-sizing is mostly proprietary information of fiber manufacturers. However, its impact cannot be minimized as shown in the figure below.
Poor Fiber-Matrix Adhesion. Good Fiber-Matrix Adhesion. Figure 9. Impact of fiber-sizing on fiber-matrix adhesion. In the above micrograph, the arrow points to good fiber-matrix adhesion in fractured samples. Poor adhesion or less than critical fiber-lengths lead to fiber pull-out and weakening of the composite. It is appropriate to introduce fiber orientation at this juncture.
The fiber orientation at mold edges is influenced by the shear forces and is parallel to flow velocity fronts or mold edges. In large cross-sections, an extensional fiber orientation develops away from the mold walls. The ideal fiber orientation is always in the direction of the stress induced in the part. The next figure illustrates the situation.
Figure Arrows point to the changes in part design to facilitate injection molding. As shown in the above figure, the original part A was a die-cast alloy. To convert it to a LFT composite, it was important to first, reduce cross sections so that fiber orientation would not vary in the middle of the cross sections. The optimized part is shown to the right B , with the arrows indicating the changes made to the part design. These changes must not compromise the structural integrity.
Hence, a structural analysis FEA was conducted to analyze the state of stress, as shown below. Stresses in the part light colors and their direction indicated by the arrow. It was therefore important to orient the fibers in the direction shown in Figure This was achieved by locating the gate in an unusual location in comparison to the one recommended by Mold Flow analytical software MFA. As shown in Figure 12, the recommended gate location is in the plane of symmetry of the part.
However, through an iterative process of FEA and MFA, the selected gate location was finally located to the side of the part to achieve a fiber orientation parallel to the stress. A Best gate location indicated by arrow and B selected gate location. As the final consideration, weld lines were monitored for various gate locations until it could be verified that the chosen gate location would not give rise to weld lines in the critically stressed portions of the part.
The figure below illustrates this strategy. Selected gate location yields fibers oriented in the stress direction and weld lines are herded out of the stressed region. Injection molding and its variants such as Injection-Compression molding also influence fiber orientation and resulting properties. Tensile samples were cut out and properties measured across the panel.
As shown in Figure 14, test plaques were molded using injection and injection-compression molding processes. In the figure below, we show how traditional injection molding, i. Alternatively, injection-compression, where the mold-cavity is filled prior to applying the injection press tonnage causes lower shear gradients in the melt. Injection Molding. Injection-Compression Molding. The large shear force gradient in conventional injection molding leads to high shear-induced fiber-orientations.
In a low shear environment, fiber orientations are fairly random across the molded plaque. Hence, test specimens from across the molded panel show lower variations. As seen in Figure 16, injection-compression molding is beneficial to orthotropic fiber orientation in the molded part. Variation of tensile strength across the molded panel in injection and injection-compression processes. We have attempted to showcase a systematic approach to designing for metal replacement with LFT composites.
Traditionally, the only variable available to the design engineer is the fiber content in the selected matrix.
However, as we show, the design space can be expanded by the judicious combination of other choices available to design and manufacturing engineers. PlastiComp's long fiber technology experts can help you get from concept to production using our composite materials that will enable you to make better products. Emily Schultz Business Development Rep. Solution Collaboration We work with you to design and make your products better.
Custom Composites We produce materials to your performance and design needs. Velocity Improved flow fills thin walls or enhances surface aesthetics. Efficient fatigue analysis for metals was developed by understanding the microscopic behavior crack nucleation and initiation and bringing it to the macroscopic level by combining it with the matching test data SN curves etc.
Similar approaches can be applied to composite materials as well. The paper gives a comprehensive review of fatigue simulation of fiber reinforced composite, based on the authors' experience in this field for different types of composites like random fiber reinforced to textile reinforcements, from detailed micro-structure analysis to efficient multi-scale algorithms, and from structural applications to detailed fatigue analysis. Article :. Need Help? Gem Mathew, Laly A. Pothen, Sabu Thomas, Influence of polarity parameters on the mechanical properties of composites from polypropylene fiber and short banana fiber, Composites: Part A 41 Asaithambi, G.
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Ganesan, S. J, Dr. Srinivasa Rao, Madhusudan. All Rights Reserved. Log In. Paper Titles. Article Preview. Abstract: In the recent scenario, the focus for the environmental pollution and the piling of products from non-renewable and non-biodegradable resources has forced many researchers to develop new eco-friendly and biodegradable materials.
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- Action: A Selection of Passages from the Teachings of J. Krishnamurti (1st Edition).
Add to Cart. Applied Mechanics and Materials Volume Main Theme:. Mechanical Engineering Design. Edited by:. Selvaraj, Dr. Alphin, Dr. Nalla Mohamed, Dr. Online since:. September Cited by. Related Articles. Paper Title Pages.
Aerospace & Defense
Authors: Piyush P. Gohil, A. Abstract: Development of composite materials requires reinforcement and matrix in which fiber is finest suitable material for reinforcement which improves properties of materials. The use of high strength fiber leads to birth of advanced composites, which are mainly used, for high strength application or aerospace application.
However, the use of medium strength and low strength fiber available in nature are also having enough potential for other application where high strength are not critical but it can provide a feasible range of alternative materials to suitable conventional material.
Simulating Fiber-Reinforced Composites
Several billion tons of fillers and reinforcements are used annually in the plastics industry, and there is a huge potential market for recyclable, energy efficient and more environmentally friendly composite materials. The present work examines the different types of natural fiber available for the development potential composites.
The attempts are already made for jute, flax and sisal natural fibers provides data from literature but there is lack of experimental data availability for unidirectional natural fiber composite like cotton, pineapple, banana fiber reinforced unidirectional composite. It is decided to carry out the systematic experimental study for the effect of volume fraction of reinforcement on longitudinal strength as well as elastic modulus using developed mould-punch set up and testing aids.