Aluminum-Matrix Composite [AMC] first appeared for automotive parts about 40 years ago, and now, as countless applications have demonstrated their functions and highlighted their sustainable appeal, it seems that they are beginning to attract manufacturers and engineers. The greater the interest in finding viable alternatives to existing materials.
As early as the 1980s, when AMC first appeared, their advantages were often oversold, and their attributes were largely unproven, which weakened their potential and had little impact on their reputation. With the wider adoption of carbon composite materials, AMC was quickly forgotten by manufacturers and engineers, and quickly out of sight. However, nearly four years later, the subsequent R&D investment in the manufacture of these composite materials has made progress, which is considered to have changed the market somewhat. Industries such as the automotive and aerospace industries are under constant pressure to improve performance, and as weight reduction plays a key role, AMC is no longer the bottom layer and is quickly becoming a “new” solution to meet the needs of legislation and other growing industries.
One of the pioneers of AMC was the British company Alvant. Originally established in 2003 at CMT, Alvant created a process called Advanced Liquid Pressure Forming (ALPF). The company combines aluminum as a matrix with high-strength reinforcing fibers to create high-performance aluminum-based composite materials. There are four series of AMC materials, which are similar in concept to sandwich materials. Traditional sandwich materials are usually assembled from carbon composite materials or unreinforced metal plates with various honeycomb cores. Metal plate sandwiches are usually flat 2D panels, while carbon composite materials can be in 3D form. Alvant uses a single manufacturing process for its CorXal products to provide ultra-high stiffness and low density (~1.9g/cc).
High-strength, high-performance AMC
Compared with non-reinforced metals, AMC also has lighter weight and excellent wear resistance, as well as special thermal and electrical properties, making it very suitable for the engineering design of durable lightweight components in harsh environments. Compared with polymer fiber reinforced materials (such as carbon composite materials), they also have many advantages. These include higher lateral strength and stiffness, higher thermal working range, better wear resistance, superior damage tolerance and easier repair.
In fact, Alvant believes that compared with steel, AMC is half the strength of steel. This means that high-load components made of traditional metals (such as steel, titanium, and aluminum) can be replaced by lightweight, low-inertia components without any increase in package size.
In order to manage cost and complexity, components do not necessarily have to be made entirely of aluminum-based composite materials; for example, if they have low-stress areas that do not require enhanced mechanical properties. In this case, the component can be locally reinforced by a method called hybrid AMC. In these applications, by applying AMC inserts to larger aluminum parts, performance can be accurately provided where needed. This limits fiber content, simplifies AMC blade geometry and reduces costs, while improving component performance and capabilities.
Wide range of applications
The production readiness of AMC also proved timely. As the automotive, aerospace, and marine industries continue to increase commercial demand for sturdy but lighter parts, manufacturers are looking for ways to improve product capabilities and performance while achieving ambitious goals for fuel efficiency and sustainability. They also proved their ability, especially when safety and reliability are of paramount importance, with potential application value in high-pressure sealing, safe landing gear and seats. Where performance, efficiency, and accuracy are critical, other use cases include robots, electric motors, and car suspensions. Because AMCs can withstand high temperatures (~300oC), they are suitable for components in high-voltage battery systems.
Product manufacturers and the industry as a whole are increasingly aware of how AMC can sometimes be a better alternative to other composite materials or non-reinforced metals. This is obvious. Partners in the aerospace and automotive industries have signed new projects with Alvant. It is also obvious.
In recent years, aerospace companies, landing gear systems, and automakers have all launched cooperative projects with Alvant, showing that the industrial sector is queuing to become early adopters of AMC.
The company has completed a three-year, ￡1.2 million research and development program. The project collaborated with the industry’s world-leading GE Aviation, motor and controller manufacturers, and the National Composite Materials Center to create a new computer-aided engineering (CAE) software modeling package for AMC design and analysis to shorten the product Development cycle.
The project has reduced the weight of the rotor of axial flux motors (such as those used in electric vehicles) by 40% while increasing the power-to-inertia ratio potential of the rotor. In addition, the number of parts in the assembly line is reduced to shorten assembly time.
According to Alvant, with the increase in electrification, automakers are seeking to optimize motor efficiency maps; for example, by improving efficiency as a function of torque and speed that ultimately determine vehicle energy consumption. The challenge for the industry is to identify ways to improve efficiency and performance while simplifying manufacturing and overall costs.
"Using AMC, we have been able to reduce weight while maintaining the stiffness and strength of the electric rotor, minimizing parasitic mass and producing a better power-to-weight ratio of the entire motor, thereby improving efficiency, range and responsiveness," said the relevant person . "In addition, we can also provide better heat resistance up to 300°C, making AMC a more suitable material than polymer composites for applications such as motors, batteries, energy recovery systems, fans, and flywheels."
Current landing gear systems are usually stronger and heavier than necessary, as the proven safety record allows the continuation of the proven technology. However, they account for about 3% of the aircraft's weight and have a corresponding effect on fuel consumption.
"The project aims to use new materials and manufacturing methods to develop and demonstrate technologies that can reduce landing gear weight, fuel consumption and noise, while improving reliability and reducing maintenance, repair, and operating costs," the relevant personnel added.
Alvant's contribution to the project is the design, manufacture and testing of AMC brake levers. The goal is to reduce the weight by 30% compared to the same titanium parts while maintaining the same strength as steel.
“A key goal of the large landing gear project is to test and demonstrate as many technological advancements as possible,” Thompson continued. "Alvant provides fatigue and stress testing components to aerospace Tier 1 suppliers, marking a big step forward in demonstrating the reliability and airworthiness of our unique materials."
Alvant firmly believes in opening up important opportunities and urgently needs the industry to take different thinking and actions as we enter the future, by investing in sustainable materials for new and more fuel-efficient aircraft, helping to achieve net zero carbon emissions by 2050.
Alvant is currently considering exploring further potential aerospace and defense applications of its CorXal material. One example includes adding a single piece of AMC to the leading edge of an aircraft wing.
Aircraft wings are subject to great aerodynamics, huge changes in temperature, and are susceptible to birds and lightning strikes. It has been found that existing materials used in traditional wing manufacturing are susceptible to degradation of the bond between the skin and the core element. This may be caused by environmental factors such as temperature, moisture ingress and pollution, which can have a negative impact on the integrity of the bond. The result is to design components with excessive safety factors to compensate for this potential tendency to degradation.
AMC is driving environmental change
Arguably the most important thing is the sustainable characteristics of AMC, thanks to the ability to separate the fiber from the aluminum at the end of the life cycle. Manufacturers must increasingly incorporate the entire life cycle cost into the design, which is an area where AMC scores higher. Nowadays, people are increasingly aware of certain shortcomings of materials such as carbon composites and polymer composites. The nature of sustainability has now changed its scope, from only focusing on the development of sustainable materials to also considering the entire product life cycle and the ability to reuse. This is now a very important consideration in design and development.
Stakeholders now have different expectations of companies, putting unsustainable materials under stricter scrutiny, and promoting the sustainable development trend of manufacturing.
However, there is a bigger picture, an important call to action that requires immediate attention. It is clear that the earth is being threatened by the irreversible effects of climate change. The biggest challenge is not only trying to correct this, but also fighting the misconceptions of many manufacturing organizations that sustainability is difficult and difficult to achieve, and more importantly, it is costly and hurts profits. AMC is just one example of innovative materials, which to a large extent prove that manufacturing can be done not only in a more sustainable way, but also in a cheaper way, because sustainability can increase efficiency. Fundamentally, it's about using materials that optimize energy use in the production process and reduce waste, thereby saving costs.