CONSTRUCTION MATERIALS

aircraft is in flight, lift forces act upward against the wings, tending to bend them upward. The wings are prevented from folding over the fuselage by the resisting strength of the wing structure. The bending action creates a tension stress on the bottom of the wings and a compression stress on the top of the wings. Q4-1. The resistance to pulling apart or stretching produced by two forces pulling in opposite directions along the same straight lines is defined by what term? Q4-2. The resistance to crushing produced by two forces pushing toward each other in the same straight line is defined by what term? Q4-3. Define the term shear as it relates to an aircraft structure. Q4-4. Define the term bending. Q4-5. Define the term torsion. CONSTRUCTION MATERIALS LEARNING OBJECTIVE: Identify the various types of metallic and nonmetallic materials used in aircraft construction. An aircraft must be constructed of materials that are both light and strong. Early aircraft were made of wood. Lightweight metal alloys with a strength greater than wood were developed and used on later aircraft. Materials currently used in aircraft construction are classified as either metallic materials or nonmetallic materials. 4-3 TORSIONAL STRESS PROPELLER ROTATION ANfO4O2 Figure 4-2.—Engine torque creates torsion stress in aircraft fuselages. TENSION ANf0403 Figure 4-3.—Bending action occurring during carrier landing.