Researchers from Tokyo University of Science have developed a new design method that could lead to lighter, faster, and cleaner vehicles and airplanes. Their technique, published in Composite Structures, simultaneously optimizes fiber thickness and orientation. As a result, it reduces the weight of reinforced plastic parts commonly used in aerospace, civil engineering, and sports equipment.
Traditionally, efforts have mostly focused on enhancing the strength of carbon fiber composites. However, the Tokyo researchers’ new design method optimizes both fiber thickness and orientation. Typically, carbon fibers are combined with other materials to make a composite, such as carbon fiber reinforced plastic (CFRP), which is popular for its strength, rigidity, and high strength-to-weight ratio. Some studies have examined how to improve CFRPs, particularly through a technique called “fiber-steered design,” which optimizes fiber orientation to enhance strength. The fiber-steered design approach, however, had a major flaw.
“Fiber-steered design only optimizes orientation and keeps the thickness of the fibers fixed, preventing full utilization of the mechanical properties of CFRP,” research team member Dr. Ryosuke Matsuzaki told Canadian Plastics. “A weight reduction approach, which allows optimization of fiber thickness as well, has been rarely considered.”
“Simultaneous Optimization Technique” Reduces CFRP Weight Without Affecting Strength
Faced with this dilemma, the researchers proposed a new design technique for simultaneously optimizing orientation and thickness depending on the composite structure’s location, which reduced the CFRP’s weight without affecting strength. According to their research, the method includes three phases.
- The Preparatory Phase:
During this phase, the researchers performed an analysis using the finite element method (FEM). As we discussed in a previous post, FEM is a numerical solution that breaks down a much larger, complex problem into a series of smaller ones (“finite elements”) in order to make the overall problem easier to examine. This equation is then used to create a digital simulation known as the finite element analysis, which gives engineers a more detailed look into the design and how its various elements work together. The team used the simulation “to determine the number of layers, enabling a qualitative weight evaluation by a linear lamination model and a fiber-steered design with a thickness variation model.”
- The Iterative Phase:
The team implemented the iterative process to “to determine the fiber orientation by the principal stress direction and iteratively calculate the thickness using ‘maximum stress theory.’”
- The Modification Phase:
During this step, the researchers made “modifications accounting for manufacturability by first creating a reference ‘base fiber bundle’ in a region requiring strength improvement and then determining the final orientation and thickness by arranging the fiber bundles such that they spread on both sides of the reference bundle.”
This simultaneous optimization technique led to a weight reduction of more than five percent and allowed for higher load transfer efficiency than what fiber orientation achieves by itself. In the future, the method could reduce the weight of CFRP parts that support greener transportation systems.
“Our design method goes beyond the conventional wisdom of composite design, making for lighter aircraft and automobiles, which can contribute to energy conservation and reduction of CO2 emissions,” Dr. Matsuzaki told Canadian Plastics.
FEM analysis is becoming an increasingly popular research tool, including in the field of photonics, where the method has contributed to a number of recent breakthroughs. Check out some of the latest innovations in optics research supported by this simulation tool.
Finite Element Method (FEM) for Photonics
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Tokyo University of Science. (24 May 2021). New optimization approach helps design lighter carbon fiber composite materials. ScienceDaily.
Tokyo University of Science. (2 June 2021). Tokyo researchers hit on new design method to reduce weight in reinforced plastics. Canadian Plastics.