IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS Composites materials (Nov. 2019) A. M. Metawea INTRODUCTION MATERIALS HAVE AN OBVIOUS INFLUENCE ON HUMANKIND, THAT PERIODS OF HISTORY HAVE BEEN NAMED AFTER MATERIALS. COMPOSITES MATERIALS ARE ONE OF THE DOMINANT MATERIALS THAT HAVE GROWN STEADILY OVER THE LAST FIFTY YEARS. COMPOSITES MATERIALS HAVE PENETRATED NEW MARKETS WITH SO MANY APPLICATIONS. COMPOSITES MATERIAL IS A MATERIAL MADE FROM MORE THAN ONE MATERIAL TO CHANGE THE PHYSICAL AND CHEMICAL PROPERTIES OF THE MAIN COMPONENTS. GETTING A NEW MATERIAL WITH MORE PREFERRED CHARACTERISTICS IS THE MAIN GOAL OF COMPOSITES MATERIALS. VARIOUS METHODS OF ADDING MATERIALS TOGETHER TO GET EXACT NEW COMPOSITES MATERIAL WITH EXACT CHARACTERISTICS, EACH HAS ITS ADVANTAGES AND DISADVANTAGES THAT SHOULD BE CHOSEN CAREFULLY TO PERFORM IT RIGHT. METHOD Choosing an exact manufacturing process mainly depends on the type of matrix and fibers, the costeffectiveness and the required temperature to form the part. Fiber Composite Matrix is mainly made of adding Fiber to provide strength and stiffness to Matrix to protect and transfer load through fibers. The manufacturing process is very important that it should be considered initially. Each manufacturing process has its advantages and disadvantages and its exact limitations on the structural design of the part. Therefore, limitations, cost, production rate, advantages, and disadvantages should be considered by the designer. There are three main types of composites manufacturing processes; open molding closed molding and cast polymer molding. Some methods will be illustrated properly including their pros and cons and technique. Open means that the raw material is exposed to air while their cure or hardening. Three methods are included. 1) Hand Lay-up Pros: • Common and cheapest. • Suitable for manufacturing a variety of composite products from all sizes (small to large). • Simple processing and low-cost tools. Cons: • Production quantity per mold is low, but this can be handled using many molds. • Need many skillful operators who can bear hard physical work. The technique: First, the gel coat is applied to the mold to preserve a high-quality surface. Roll stock fiberglass reinforcement is manually placed on the mold after the gel is cured. The laminating resin is then added by either pouring, brushing or using a paint roller (it is used to consolidate the laminate, remove the air and completely wet the reinforcement). Other layers of fiberglass reinforcement are added to build laminate thickness. Low-density core materials as end-grain balsa, foam, and honeycomb can be used to stiffen the laminate. 2) Spray-up Pros: Suitable for manufacturing a variety of composite products from all sizes (small to large). Faster than Hand Lay-up method in molding complex shapes. Simple processing and low-cost tools. Portable equipment allows for on-site fabrication with almost no size limitations. The operator can control thickness and consistency. Cons: Production quantity per mold is low, but this can be handled using many molds. It depends more on the operator. Technique: First, the gel coat is applied to the mold to preserve a high-quality surface. Strand glass and resin are then added using a chopper gun on the mold. The laminate is rolled to make all glass strands IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS saturated and compact the chop. More layers are added to get the needed thickness. Roll stock reinforcements, such as woven roving or knitted fabrics, can be used in conjunction with the chopped laminates. The third process is open molding is Filament Winding that also has its advantages, disadvantages, production rate and technique. A quick look at the other two types of molding; closed molding and cast polymer molding will be provided. In closed molding, raw materials cure inside a vacuum bag or a twosided mold. It is usually automated and requires special large equipment with a high production rate. Vacuum Bag Molding, Vacuum Infusion Processing, Resin Transfer Molding, Compression Molding, Pultrusion, Centrifugal Casting, and continuous lamination are all types of closed molding with their special pros and cons and techniques. The main disadvantage of the closed Molding is that it requires high-cost equipment and professional labors, while the advantages of these processes are a high rate of production and high efficiency. Cast polymers are unique; they don’t have fiber reinforcements. They are designed to make a specific shape and size with specific strength for an exact application. Gel Coated Cultured Stone Molding and Solid Surface Molding are types of Cast Polymer Molding. Results 3) Many applications are developed from the composites materials, which as shown has provided us with new preferred characteristics. With all these benefits, another aspect designers should consider carefully, which is a failure. Failure of a structural element happens when this element cannot perform its intended function. It seems obvious that material failure is the only type of failure, yet, it is not. Excessive deflection is also a type of failure that occurs when the performance of the structure is compromised. The element does not need to be collapsed to be considered failed, partially damaged materials could also be considered damaged. Fracture and damage are harder to predict than deflections. To design well, a designer should consider testing the strength of the design and developing tools to select materials with dimensions and configurations to help the structure perform its function safely. Discussion 1) A brief look at manufacturing processes has been provided with insightful describing of two important processes. The strength which is a significant factor of composites material was illustrated briefly. Many applications were developed to gain more efficiency when manufactured from composites materials. Wind turbines blades for example made from composites material to increase its strength and ability to bear high wind velocities and forces on the blades and also became lighter and perform better with higher efficiency. A good designer carefully considers the material is chosen, manufacturing process, strength, cost, and efficiency. Testing the design before construction can be done using finite element analysis. Materials may be tested during and after construction through ultrasonic, thermography, Shearography, and X-ray radiography. References E. J. Barbero, Introduction to composite materials design. Boca Raton, FL: CRC Press, Taylor & Francis, 2018. “Desktop Engineering Magazine - The Life of Composite Materials,” archive.is, 02-Dec-2007. [Online]. Available: https://archive.is/20071202141018/http://66.195.41.10/Ar ticles/Feature/The-Life-of-Composite-Materials200704101800.html. [Accessed: 01-Nov-2019]. “All You Need to Know About Composites,” Composites Lab. [Online]. Available: http://compositeslab.com/. [Accessed: 01-Nov-2019]. M. Hinton and A. Kaddour, “The background to Part B of the Second World-Wide Failure Exercise: Evaluation of theories for predicting failure in polymer composite laminates under three-dimensional states of stress,” Journal of Composite Materials, vol. 47, no. 6-7, pp. 643–652, 2013.
