Balearic PAU Technology & Engineering II key terms

Within the elastic range, the deformation of a material is directly proportional to the applied stress, so stress divided by strain gives a constant called the elastic modulus.

The maximum stress a material can bear while still recovering its original shape completely when the load is removed; beyond it, permanent deformation begins.

The ratio of tensile stress to tensile strain in the linear elastic region, measuring how stiff a material is: higher values mean less deformation for the same load.

The stress at which a material begins to deform plastically, so that removing the load leaves a permanent change of shape.

The energy a material absorbs before fracturing, combining strength and ductility; brittle materials such as glass have low toughness despite high hardness.

Resistance of a surface to being scratched or indented by another body. It is measured by standard indentation tests and does not by itself indicate toughness.

Controlled heating and cooling of a metal to change its internal structure and therefore its mechanical properties, for example quenching to harden steel or annealing to soften it.

A metallic material made by melting a base metal with other elements to obtain properties the pure metal lacks, such as stainless steel or brass.

A material formed by combining two or more constituents with different properties, so the result performs better than either alone, as in glass-fibre reinforced polyester.

The condition in which a material's properties differ depending on the direction of measurement, typical of laminated composites and of rolled or drawn metals.

A sketch of a body isolated from its surroundings showing every external force and moment acting on it, used to write equilibrium equations.

The state of a body at rest in which the vector sum of all forces and the sum of all moments about any point are both zero.

The force exerted by a support or constraint on a structure in response to applied loads, obtained from the equilibrium conditions of the whole system.

The ratio between the output force (or torque) delivered by a machine and the input force applied to it, always limited in practice by friction losses.

The ratio between the distance moved by the effort and the distance moved by the load in a machine, fixed by its geometry and independent of friction.

The ratio of the number of teeth on two meshing gears, which sets the relationship between their speeds and torques in the opposite sense.

A transmission pairing a screw-like worm with a toothed wheel, giving a large speed reduction and self-locking behaviour in one direction.

A mechanism of four rigid links joined by four turning pairs, used to convert a continuous rotation into an oscillating or complex motion.

A rotating profile that pushes a follower to produce a specific, often non-uniform, output motion determined by the cam's shape.

The number of independent input motions a mechanism needs to define its position completely, calculated from the number of links and joints.

For a resistive element at constant temperature, the voltage across it equals the current through it multiplied by its resistance.

A connection in which components form a single path, so the same current flows through all of them and the supply voltage divides among them.

A connection in which components share the same two nodes, so the voltage across each is equal and the total current is the sum of branch currents.

The total opposition of a circuit to alternating current, combining resistance with reactance and expressed as a complex quantity in ohms.

The cosine of the phase angle between voltage and current in an AC circuit; it equals one for purely resistive loads and is reduced by inductive reactance.

A supply arrangement of three voltages of equal magnitude displaced 120 degrees in phase, allowing constant power delivery and efficient motor operation.

A high-gain differential voltage amplifier used with external feedback networks to build comparators, filters, amplifiers and signal-conditioning stages.

The path that returns a measured portion of the output to the controller so it can compare it with the setpoint and correct the error.

A control scheme in which the actual output is measured and compared with the desired value, and the resulting error drives corrective action.

A control scheme that acts on the system without measuring the result, so it cannot compensate for disturbances or drift.

The reference value that a control system is required to maintain, against which the measured output is compared to compute the error.

A device that converts a physical quantity such as temperature, position or light into an electrical signal usable by a controller.

A component that converts a control signal into physical action, for example a motor, solenoid valve or pneumatic cylinder.

A programmable logic controller: an industrial digital computer that runs a stored program to read inputs and drive outputs in real time.

A graphical programming language for programmable controllers drawn as rungs between supply rails, resembling relay logic circuits.

A pneumatic valve with five ports and two stable positions, used to extend and retract a double-acting cylinder by redirecting supply and exhaust.

A linear actuator in which compressed air is applied alternately to both sides of the piston, producing powered motion in both directions.

A schematic representation of compressed-air components and their connections using standard symbols, showing flow paths and control logic.

A valve that regulates the rate of fluid passing through it, used to set actuator speed by restricting flow or bypassing it.

Material removal carried out by machine tools guided by a stored numerical program, giving repeatable geometry and complex toolpaths.

The standard instruction language for numerically controlled machine tools, specifying motions, feed rates, spindle speeds and tool changes.

The permissible variation in a dimension or geometric feature, stated on a drawing so that parts assemble correctly without unnecessary precision.

The intentional relationship between the sizes of mating parts, classified as clearance, interference or transition according to the intended assembly.

A drawing method representing a three-dimensional object by views projected onto perpendicular planes, typically front, plan and side elevations.

The ratio between a dimension on a technical drawing and the corresponding real dimension of the object, such as 1:20 for a reduction.

An itemised list of every component, material and quantity needed to build a product, used for purchasing and cost estimation.

A forecast of the income and expenditure of a project, itemising materials, labour, tooling and contingencies to control cost.

A systematic assessment of the environmental impacts of a product from raw material extraction through manufacture, use and end-of-life disposal or recycling.

Designing a product to reduce its environmental impact throughout its life, by choosing materials, reducing energy use and planning recyclability.

The total greenhouse gas emissions, expressed as carbon dioxide equivalent, caused directly or indirectly by a product, activity or organisation.

Meeting present needs without compromising the ability of future generations to meet theirs, balancing environmental, social and economic criteria.