Balearic PAU Technology & Engineering II flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Allotropic transformation

Change of crystal structure of a solid element with temperature or pressure, as pure iron changes from BCC ferrite to FCC austenite near 912 °C; this enables steel hardening by quenching.

Yield strength

Stress at which a material begins permanent plastic deformation, taken at 0.2% offset strain for metals without a clear yield point; the design limit for structural parts.

Specific strength

Ratio of strength to density (σ/ρ), used to compare lightweight structural materials; high values favour titanium and aluminium alloys over steel in weight-critical designs.

Embodied energy

Total energy consumed to extract, process, manufacture and deliver one kilogram of a material, expressed in MJ/kg; primary aluminium is high, recycled aluminium and timber are low.

Static equilibrium conditions

A body at rest satisfies the sum of forces equals zero and the sum of moments about any point equals zero; used to compute support reactions of beams and trusses.

Gear velocity ratio

Ratio of input to output angular velocity in a gear pair, equal to the output tooth count divided by the input tooth count; external meshing reverses the direction of rotation.

Grashof condition

A four-bar linkage has at least one fully rotating link when the shortest plus longest link length is less than or equal to the sum of the other two lengths.

Mechanical power

Rate of doing work in a machine, computed as force times linear velocity or torque times angular velocity; efficiency is output power divided by input power, always below one.

Kirchhoff current law

At any electrical node the algebraic sum of currents is zero: currents entering equal currents leaving. It applies to DC and AC circuits and underpins nodal analysis.

Thevenin theorem

Any linear two-terminal network can be replaced by one voltage source Vth in series with one resistance Rth, simplifying load calculations; Vth is open-circuit voltage.

Resonance in RLC

Condition where inductive and capacitive reactances cancel, so impedance equals resistance and current is maximum; resonant frequency is one over two pi root LC.

Power factor

Cosine of the phase angle between voltage and current; active power equals RMS voltage times RMS current times this factor, and low values increase cable losses.

Zener diode

Silicon diode designed to operate in reverse breakdown at a specified voltage, holding that voltage nearly constant; used for simple voltage regulation and overvoltage protection.

Closed-loop control

Control scheme where a sensor measures the output, a comparator computes the error against the setpoint, and the controller acts to reduce that error despite disturbances.

PID controller

Controller combining proportional, integral and derivative action on the error signal: proportional speeds response, integral removes steady-state error, derivative damps overshoot and noise.

NTC thermistor

Resistive temperature sensor whose resistance decreases as temperature rises; cheap and sensitive, used in measurement bridges and temperature compensation circuits.

PLC scan cycle

Repeated sequence of reading input modules, executing the stored ladder program and updating output modules; total duration is the scan time, typically milliseconds.

Stepper motor

Actuator that rotates in fixed angular steps when pulses arrive, allowing open-loop position control by counting pulses; used in printers and positioning tables.

Pascal's principle

Pressure applied to an enclosed fluid is transmitted equally in all directions; a hydraulic press multiplies force by the ratio of piston areas while the smaller piston travels farther.

5/2 directional valve

Pneumatic valve with five ports and two positions that directs supply to one cylinder side while exhausting the other; two pilot or solenoid actuators switch the positions.

Meter-out speed control

Throttle valve placed in the exhaust line of a cylinder to limit rod speed; it gives smoother, more stable motion than meter-in control when the load overruns.

FRL unit

Combined filter, pressure regulator and lubricator installed at the inlet of a pneumatic circuit to clean air, set working pressure and add oil mist for moving parts.

Material removal rate

Volume of material cut per unit time in machining, approximately cutting speed times feed times depth of cut; governs machining time and required power.

Break-even point

Production volume at which total revenue equals total cost, computed as fixed cost divided by unit price minus unit variable cost; below it the product loses money.

Just-in-time production

Lean strategy where materials arrive and parts are made only as demanded, minimising inventory; requires reliable suppliers, short set-ups and kanban signalling.

First-angle projection

Drawing convention used in Europe where the object is placed between observer and projection plane, so the top view is drawn below the front view.

ISO tolerance fit

Combination of a hole basis letter and shaft letter defining clearance, transition or interference; H7/h6 gives a sliding fit with small clearance.

Critical path method

Network planning technique where the longest path through dependent activities sets project duration; activities on that path have zero slack and delay the whole project.

Bill of materials

Itemised list of every component, quantity, material and reference code needed to build a product, used for purchasing, assembly and cost estimation.

Life-cycle analysis

ISO 14040 method quantifying environmental impacts of a product from raw material to disposal, structured as goal and scope, inventory, impact assessment and interpretation.

Circular economy

Economic model that keeps materials in use through reuse, repair, remanufacture and recycling, reducing virgin resource extraction and waste compared with the linear take-make-dispose model.

Technology transfer

Process by which knowledge, patents or prototypes move from research centres to industry through licences, spin-offs or joint ventures, turning research into marketable products.