DelftX: AEASM1x Introduction to Aerospace Structures and Materials

Material with mechanical properties depending on the direction.

Structure that takes up all forces during operation of the vehicle.

Property of material that allows little bending or deformation without shattering.

Engineering materials containing two or more distinct and structurally complementary substances with different physical or chemical properties, having structural or functional properties not present in the individual substances.

Reaction produced in material as the result of heating or cooling.

In general: degradation of engineering materials due to chemical reaction with its environment.

Metal specific; electrochemical oxidation in reaction with an oxidant such as oxygen.

The ability of the structure to sustain anticipated loads in the presence of fatigue, corrosion or accidental damage until such damage is detected through inspections or malfunctions and is repaired.

Weight of a unit volume of material

Property of metal that allows it to be permanently drawn, bent, or twisted into various shapes without breaking.

The ability of the structure to sustain degradation from sources as fatigue, corrosion, accidental damage and environmental deterioration to the extent that they can be controlled by economically acceptable maintenance and inspection programs.

Property enables material to return to its original shape when the force which causes the change of shape is removed.

Load divided by the original cross-section of the material or component.

Fail-safe is the attribute of the structure that permits it to retain required residual strength for a period of un-repaired use after failure or partial failure of a principal structural element.

Damage phenomenon induced by multiple load cycles below ultimate strength of material or structure causing permanent deterioration of material or structure resulting in a reduction in load bearing capability.

Composite material combining metal sheets and fiber reinforced composites.

Measure of energy needed to fail a specimen containing a crack.

Electrochemical process in which one metal corrodes when in electrical contact with a different type of metal or material and both metals are immersed in a substance containing electrolyte.

Maximum variation allowed in form or positioning.

The temperature at which polymers exhibit a transition from a more glassy (hard/brittle) state to a rubbery (elastic/flexible) state.

Ability to resist abrasion, penetration, cutting or permanent distortion.

Measure of energy needed to fracture a notched specimen.

Material having identical mechanical properties in all directions.

Measure for material resistance against imposed Elastic deformation. The value of this Young’s modulus is a characteristic value for a material; a high value indicates a stiff material, a low value a flexible material

Stress that acts perpendicular to the surface of the material

Normalized change in axial length of an object.

Material with properties that differ in all three directions.

The ratio between the transverse strain and the axial strain in a material.

Critical load bearing structure of an aircraft or spacecraft that in case of severe damage will fail the entire aircraft/spacecraft.

Approximation of isotropic material by placing multiple anisotropic layers in different directions.

A simple first estimate of properties of a composite, based on the properties of its constituents: $$\rho_{FRP}=\rho_F\frac{V_F}{V_{FRP}} + \rho_M\frac{V_M}{V_{FRP}}$$

Resin Transfer Moulding

Safe-life of a structure is the number of flights, landings, or flight hours, during which there is a low probability that the strength will degrade below its design strength.

Disturbances in the stress field remain limited to the direct neighbourhood of the location of disturbance.

Structural elements of an aircraft or spacecraft that carry only air and inertial loads generated on or in the secondary structure

Measure for material resistance against shear. It is related to the modulus of Elasticity: $$G = \frac{E}{2(1 + \nu)}$$

Ratio of deformation of a material due to shear. It it the angle a square block deforms at when a parallel force is applied.

Stress that acts parallel along the surface of a material.

Material property divided by its density.

Parameter describing the relation between the peak stress at the (blunt) notch root and the nominal (netto) stress in the cross-section.

Parameter describing the severity (intensity) of stresses near the crack tip.

Resistance against fracture. Represented by the area under the stres-strain curve. Expressed in J/m³

Load divided by the actual cross-section of the material.

Vacuum Assisted Resin Transfer Moulding

Vacuum Infusion