Advanced Materials Human Powered Aircraft Group Advanced Materials

Advanced Materials Human Powered Aircraft Group

Advanced Materials Advanced materials are used in aircraft design to: -Reduce weight -Improve strength -Design morphing wings -Create self-healing structures

Examples of Advanced Materials • Memory Polymers • Composites • Biocomposites • Thermoplastics • Alloys

Memory Polymers: Veriflex and Veritex • Veriflex is a shape memory polymer resin which • • modifies its shape in response to temperature changes. Veritex is a dynamic composite that utilizes Veriflex resin as its matrix. When heated, Veritex is pliable and maintains shape as it cools, regaining structural stiffness. Once reheated it returns to its original shape and can be remolded without degrading. Future polymers may respond to light, electric fields and magnetic fields.

Composites • Composites are a combination of two or more organic or inorganic components one of which serves as a matrix holding the materials together and then other of which serves as reinforcement in the form of fibers • Composites are lightweight and strong but they are complex to manufacture, expensive and hard to inspect for flaws

Thermoplastics • Thermoplastics are a new type of materials that is replacing thermosets such as epoxy, bismaleimide, or polyimide, as the matrix for composites • Thermoplastics are easier to produce and are much more durable and tougher than thermosets

Biocomposites • Biocomposites combine plant fibers with resins to create • • natural based composite materials. High tensile plant fibers including, kenaf, industrial hemp, and flax, can be combined with traditional resins to create an alternative to traditionally steel or fiberglass applications. Some advantages over traditional composites: – – – – Reduced weight Increased flexibility Greater moldability Less expensive Sound insulation Renewable resource Self-healing properties

Alloys • Benefits of Alloys: – Decreased weight – Durable – Easy to manufacture and repair

Application to Morphing Wings • Stronger, shape memory and self-healing polymers are applicable to the design of morphing wings – Lockheed’s 14 ft remote-control aircraft makes use of Veriflex and Veritex polymers to change shape and ensure a streamline profile as the wings morph. – Nextgen Aeronautics tested a wing that's structure of aluminum lattices expanded and compressed consequently stretching and shrinking the wings silicone-rubber skin and causing the wing tips to move forward and back, and changing the wing span and chord.

Future development of Personal Air Vehicles (PAV), calls for safer, easy to fly planes. – Self-healing (often biocomposite) materials can be utilized to reduce maintenance. – An Aeronautic Vehicle Integrated Health Management System is looking into selfhealing materials that will fill cracks in the structure by breaking capsules and releasing adhesive.

Aeronautical Integrated Vehicle Health Monitoring System (IVHM) • Detection of damaging events • Characterization of the damage • Prioritization of the seriousness of the damage • Identification of the cause of the damage • Formulation of the response • Execution of the response

What is IVHM? • Intelligent sensing system – Detects and measures quantities and uses this information to make forward looking decisions – Uses thousands and perhaps millions of different sensors used to measure different quantities (stress, strain, temperature, acoustics, etc…)

How Does IVHM work? • Separates structures (skin, ribs, components, etc. . . ) into a series of cells • Each cell is equipped with a group of sensors • The sensors communicate with neighboring cells as well as a central computer.

Types of Sensors • Fiber Optic • Piezoelectric • Infrared imaging

Fiber Optic Sensors • Can measure strain, temperature and pressure • Specifically they can measure bond line integrity, • acoustic emissions, and corrosion Uses Bragg grating to measure changes in light signal – A change in stress moves the Bragg grating producing a shift in the reflected wavelength • Fiber Optics are brittle so they must be embedded into materials, this is very expensive and complicates manufacturing and repair practices.

Piezoelectric Materials • Convert mechanical input into an electrical signal • • (sensor) or convert and electrical pulse into a mechanical action (actuator) Can detect energies caused by impact events or defect generation (cracks, delamination) Arrays of sensors allow a pinpoint determination of the damage location Sensors have been able to detect cracks 0. 005 inches in length of six inches Will be embedded or surface mounted. Less expensive option

Infrared Imaging • Detects heat signatures in • • order to detect leaks, cracks, debonding, corrosion, poor electrical wiring and contacts, and to assess overall thermal profiles of components. Most often used to detect defects or damage in the propulsion system. Widely used, inexpensive

Joint Strike Fighter • Airframe Structures • Engine • Electronics • Mission Systems • Components – – Hydraulics Drive Shafts Fuel system Electrical system

Summary of IVHM • Rapidly growing field dependant on the improvement • and development of sensing technologies. It will enable less reliance on statistical based scheduled maintenance and moves towards a condition based maintenance which will greatly reduce ownership costs

References • http: //showcase. netins. net/web/creativecomposites/Biocomposites. html, Creative • • • Composites, Ltd. , 19 September 2006 http: //www. crgrp. net/veriflex. htm, CRG Industries, LLC. , 19 September 2006 “Flying off the Drawing Board”, Jeff Wise, Popular Mechanics, volume 183 no. 7, July 2006 http: //www. crgindustries. com/veritex. htm, CRG Industries, LLC, 19 September 2006 http: //www. centennialofflight. gov/essay/Evolution_of_Technology/composites/Tech 4 0. htm, U. S. Centennial of Flight Commission, 23 September 2006 http: //ammtiac. alionscience. com/pdf/2004 Material. EASE 27. pdf#search=%22 Vehicle% 20 Integrated%20 Health%20 Monitoring%20 System%22, The AMPTIAC Quarterly, Volume 8, Number 3, “Sensors and Sensing Technologies for Integrated Vehicle Health Monitoring Systems”