The leading edge of the wing that the airflow first contacts when the aircraft travels has high requirements on the hydrophobicity of the material, insect adhesion, and corrosion resistance.
North Carolina State University (North Carolina State University) recently invented a composite metal foam material, which is said to have better performance in all aspects than the currently widely used aluminum alloy material.
Afsaneh Rabiei, a professor of mechanical and aerospace engineering at North Carolina State University, one of the researchers, said: "We call this hybrid material "infiltrated CMF". It has the same weight as aluminum, but is harder and has other characteristics. It is also more conducive to aircraft performance, safety and fuel efficiency."
The CMF consists of hollow metal balls embedded on a metal support. The material of the metal balls can be stainless steel or titanium, and the metal support can also be made of steel, aluminum or alloy. In this study, the metal balls and brackets used by the researchers were made of steel. Previous research has shown that this material is very strong and can withstand .50 caliber bullets and high temperatures.
It is called "infiltration CMF" because during the manufacturing process, the material is immersed in an impermeable epoxy resin, and the resin is sucked into the metal ball and the small gaps between the metal brackets with vacuum suction. In other words, 88% of the voids in the CMF material are filled with epoxy resin.
The researchers then tested the performance of this material in terms of contact angle, insect adhesion and corrosion resistance.
The contact angle refers to the angle formed by the liquid contacting the solid surface and is an important indicator of the hydrophobicity of the material surface. The smaller the contact angle, the more water sticks to the surface of the material. The accumulation of moisture on the wings will reduce the performance of the aircraft, so the larger the contact angle of the selected material, the better. Experiments show that the contact angle of this new material is 130% larger than that of aluminum.
In addition, the wreckage of insects that unfortunately hit the aircraft is also a very unfavorable factor for the aircraft. Insect attachment index has two parts: the maximum height of the debris continuously accumulating into blocks, and the maximum area of accumulated flakes. CMF material also shows better characteristics than aluminum. The maximum accumulative height of insect stains is only 60% of aluminum; the area is only 30%.
Finally, the sandblasting experiment is used to simulate the performance of the material after a period of use and wear. The results show that in the case of maximum wear, the contact angle of the material surface is still 50% larger than that of aluminum.
The researchers said that these data show that CMF as a wing leading edge material will be more durable than aluminum, and reduce maintenance and replacement costs. It is currently a good replacement material for aluminum.