Mechanical Engineering Glossary

A category of manufacturing processes that build 3D objects by depositing material layer by layer from digital models, including technologies like SLS, FDM, and SLA. It enables complex geometries impossible with traditional methods.

The use of computer software to create, modify, analyze, and document 2D and 3D design models, serving as the digital foundation for modern engineering design, simulation, and manufacturing workflows.

The use of computer software to control machine tools and automate manufacturing processes, translating CAD models into toolpaths and machining instructions for CNC equipment.

A branch of fluid mechanics that uses numerical analysis and algorithms to solve and analyze fluid flow problems, enabling virtual testing of aerodynamic and hydrodynamic designs.

The slow, time-dependent permanent deformation of a material under constant stress, typically significant at temperatures above approximately 40% of the material's melting point in Kelvin.

The ability of a material to undergo significant plastic deformation before rupture, typically measured by percent elongation or percent reduction in area during a tensile test.

A thermodynamic quantity equal to the internal energy plus the product of pressure and volume ($H = U + PV$), representing the total heat content of a system at constant pressure.

A thermodynamic property measuring the degree of disorder or randomness in a system. The Second Law dictates that the total entropy of an isolated system always increases in spontaneous processes.

The progressive structural damage that occurs when a material is subjected to cyclic loading, leading to crack initiation and propagation, and eventually fracture at stress levels below the material's ultimate tensile strength.

A numerical method that subdivides a complex geometry into a mesh of smaller elements to approximate the solution of boundary value problems in engineering, such as stress, thermal, and vibration analysis.

A standardized symbolic language (ASME Y14.5) used on engineering drawings to define the allowable variation in a part's geometry, ensuring proper fit, function, and interchangeability.

The ratio of the number of teeth (or diameters) of two meshing gears, determining the speed and torque relationship between the input and output shafts. A gear ratio greater than 1 reduces speed but increases torque.

A material's resistance to localized surface deformation, typically measured by indentation tests such as Brinell, Rockwell, or Vickers. Hardness often correlates with wear resistance and tensile strength.

The branch of engineering that uses pressurized liquids to transmit force and produce mechanical motion, based on Pascal's law. Hydraulic systems can generate very large forces in compact actuators.

An interdisciplinary field combining mechanical engineering, electronics, computer science, and control engineering to design and create intelligent systems and products such as robots, CNC machines, and automated manufacturing lines.

In structural analysis, the second moment of area quantifies a cross-section's resistance to bending. In dynamics, the mass moment of inertia quantifies an object's resistance to angular acceleration.

The branch of engineering that uses compressed air or gas to produce mechanical motion and perform work, commonly used in industrial automation, tools, and control systems.

A dimensionless number ($Re = \frac{\rho v L}{\mu}$) representing the ratio of inertial to viscous forces in fluid flow, used to predict whether flow will be laminar or turbulent.

The dimensionless measure of deformation, defined as the change in length divided by the original length. It can be elastic (recoverable) or plastic (permanent).

The internal force per unit cross-sectional area within a material, arising from externally applied loads. Measured in Pascals (Pa) or pounds per square inch (psi).

The branch of physics dealing with heat, work, and energy transformations, governed by four fundamental laws that dictate the behavior of thermal systems.

A rotational force that causes an object to rotate about an axis, calculated as the cross product of the force vector and the position vector from the axis of rotation. Measured in Newton-meters (N·m).

The twisting of a structural member when subjected to a torque, creating shear stresses that vary from zero at the center to a maximum at the outer surface of a circular cross-section.

A fluid's resistance to deformation under shear stress, often described as the 'thickness' of a fluid. Dynamic viscosity has units of Pascal-seconds (Pa·s), and it generally decreases with temperature for liquids.

The ratio of stress to strain in the linear elastic region of a material, representing its stiffness. A higher value means the material is more resistant to elastic deformation.