Blasted: How Laser Peening Helps the F-35 Stealth Fighter Stay Stealthy

https://www.reutersconnect.com/all?id=tag%3Areuters.com%2C2018%3Anewsml_RC1CC4943C30&share=true

Blasted: How Laser Peening Helps the F-35 Stealth Fighter Stay Stealthy

This innovative, high-tech method is much better than the old way of preparing airframes for war.

The U.S. Navy is increasing its investment in sustaining the stealth properties of its F-35 fleet through a deal modification with Lockheed aimed at back-fit engineering the aircraft, providing materials support and strengthening an existing process aimed at preserving the F-35s stealth coating functionality through “laser shock peening.” 

The process, which has now been in development for several years, is described in a previous Navy report as a unique process producing a uniform result across the surface treated:

In laser shock peening, the surface of the media is first coated with an ablative layer and covered with a water tamping layer. A high-energy laser beam is fired at the metal, which creates an area of plasma on the metal’s surface. The impact creates a shock wave, which travels through the metal, and compressive residual stresses remain. This compression helps improve the metal’s damage tolerance, fatigue life and strength…” as written in a Navy news report published on Navy.mil.

Laser peening will replace the legacy approach, called “shot peening,” which sprays solid material such as glass beads or metals in kind of a sandblast fashion, explained Matthew Crisp, the F-35 Joint Program Office site lead at FRCE. (Fleet Readiness Center East)”

“With shot peening, you just randomly throw it at the surface, and it creates all these surface dimples. What you get is a very inconsistent surface profile, because it’s not controlled,” Crisp explained.

The shock peening extends and potentially improves the stealth properties of the F-35’s blend of radar-absorbent, composite materials without adding any metal or weight. Sustaining a smooth exterior to the jet is fundamental to maintaining stealth functionality, as the materials are not only built to be radar-absorbent but also devoid of any small indents or rough surfaces. Electromagnetic pings are able to send a clearer return signal when they can bounce off edges, shapes or other configurations able to render an image of an object. 

The laser shock peening is intended to complement and preserve elements of the aerodynamic exterior of the F-35 which, according to Lockheed Martin engineers, is built with specific bolts, seams, curved edges and smooth, curved protruding structures by design from its inception. Continued functionality, it goes without saying, relies upon the sustainment of the effects of these engineering techniques.

The Navy report also details some of the technical elements of the advantages laser treatment provides. Lasers bring heat, precision and an ability to blanket an area without needing to use small projectiles. Crisp explained the impact of laser peening this way:

It “creates a laser beam that’s actually square, and the intensity is consistent across the entire laser beam—it’s the exact same at the very edge of the beam as it is in the middle,” he said. “They come up with a grid pattern and stack the squares up right beside each other, so the entire surface of the part is completely uniform. You don’t have the weak spots in between these areas that would then induce cracking later.”

Kris Osborn is the defense editor for the National Interest. Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University.

Image: Reuters.