Engineering Glossary

The internal moment at a section of a structural element that causes it to bend. It equals the sum of moments of all forces acting on one side of the section.

A sudden, lateral deflection of a structural member subjected to compressive loads. It is a stability failure that can occur at stress levels well below the material's compressive strength.

The transfer of heat through a material by direct molecular contact, without bulk movement of the material itself. The rate depends on thermal conductivity, area, and temperature gradient.

The transfer of heat by the bulk movement of a fluid (liquid or gas). It can be natural (driven by buoyancy) or forced (driven by a fan or pump).

The gradual degradation of a material, usually a metal, through chemical or electrochemical reactions with its environment, such as rusting of steel in the presence of moisture and oxygen.

The time-dependent, permanent deformation of a material under constant stress, typically significant at elevated temperatures. It is critical in applications such as turbine blades and nuclear reactors.

The number of independent parameters that define the state or configuration of a system. In mechanics, a rigid body in 3D space has six degrees of freedom: three translational and three rotational.

The branch of mechanics that studies the forces and torques that cause or change the motion of bodies, combining kinematics with Newton's laws of motion.

The ability of a material to return to its original shape and dimensions after the removal of an applied load, provided the load did not exceed the material's elastic limit.

A thermodynamic property equal to the internal energy of a system plus the product of its pressure and volume, commonly used to quantify heat transfer in constant-pressure processes.

A thermodynamic quantity representing the degree of disorder or randomness in a system. The Second Law of Thermodynamics states that the entropy of an isolated system never decreases.

The weakening and eventual failure of a material caused by repeatedly applied cyclic loads, even when each load cycle produces stresses below the material's ultimate tensile strength.

The study of the geometry of motion, describing position, velocity, and acceleration of bodies or systems without considering the forces that cause the motion.

The property of a material that allows it to undergo permanent deformation without fracture when subjected to stress beyond its yield point.

The transfer of energy through electromagnetic waves. Unlike conduction and convection, radiation does not require a medium and can occur through a vacuum.

A dimensionless number that predicts whether fluid flow will be laminar or turbulent, defined as the ratio of inertial forces to viscous forces.

A force that acts parallel or tangential to a surface or cross-section, causing one part of a body to slide relative to an adjacent part.

The branch of mechanics that studies bodies at rest or in equilibrium, where the net force and net moment acting on the body are both zero.

The measure of deformation in a material, defined as the change in length divided by the original length. It is a dimensionless quantity.

The internal force per unit area within a material resulting from externally applied loads, measured in Pascals (Pa) or pounds per square inch (psi).

The permissible range of variation in a physical dimension or measured value, specifying the acceptable limits of deviation from a nominal dimension during manufacturing.

A measure of the rotational force applied to an object, equal to the product of the applied force and the perpendicular distance from the axis of rotation.

The maximum stress a material can withstand while being stretched or pulled before necking or fracture occurs.

A measure of a fluid's resistance to flow or deformation. High-viscosity fluids (like honey) flow slowly; low-viscosity fluids (like water) flow easily.

The stress at which a material begins to deform plastically. Below this stress, the material will return to its original shape when unloaded; above it, permanent deformation occurs.