Basque PAU Technology & Eng II flashcards

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

Hooke's law

In the elastic region, stress is proportional to strain: σ = E·ε, where E is Young's modulus, measured as the slope of the linear part of the stress–strain curve.

Martensite

A hard, brittle phase formed when austenite is quenched rapidly; carbon is trapped in a body-centred tetragonal lattice. Tempering afterwards restores toughness.

Vickers hardness test

A diamond pyramid indenter is pressed into the surface; hardness HV is calculated from the diagonal of the indentation. It works across the full range of materials.

Grashof condition

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

Gear module

The module m = d/z, where d is pitch diameter and z the number of teeth. Two gears can mesh only if they share the same module.

Mechanical advantage

Ratio of output force to input force in a machine. For an ideal lever it equals the ratio of input arm to output arm: MA = Li/Lo.

Moment of inertia

A body's resistance to angular acceleration. For a solid cylinder about its axis I = ½mr²; rotational kinetic energy is Ec = ½Iω².

Thevenin's theorem

Any linear two-terminal network can be replaced by a voltage source V_th in series with a resistance R_th, found from the open-circuit voltage and the deactivated-source resistance.

Power factor

cosφ = P/(V_rms·I_rms), the ratio of real to apparent power in AC circuits. Low values mean reactive current and higher line losses.

Resonance in RLC circuit

Occurs when inductive and capacitive reactances cancel (XL = XC), giving minimum impedance and maximum current at f0 = 1/(2π√(LC)).

Bridge rectifier

Four diodes arranged so both half-cycles of AC are rectified. Output DC is about 0.637 times peak voltage before filtering.

De Morgan's laws

Boolean identities: NOT(A AND B) = (NOT A) OR (NOT B), and NOT(A OR B) = (NOT A) AND (NOT B). Used to simplify logic circuits.

Closed-loop control

A system where a sensor measures the output and feeds it back; the controller acts on the error between setpoint and measured value to reduce it.

PID controller

Controller output u = Kp·e + Ki∫e dt + Kd·de/dt. Proportional acts on present error, integral removes steady-state offset, derivative damps overshoot.

PLC scan cycle

A programmable logic controller repeatedly reads inputs, executes the stored program and updates outputs in a fixed cyclic order, typically in milliseconds.

Strain gauge

A resistive sensor bonded to a surface; its resistance changes with elongation. Used to measure force, pressure or deformation through a bridge circuit.

Pascal's principle

Pressure applied to a confined fluid is transmitted equally in all directions. This underlies hydraulic presses: F1/A1 = F2/A2.

5/2 directional valve

A pneumatic valve with five ports and two positions. It directs supply air to one cylinder side while exhausting the other, controlling extend and retract.

Meter-out circuit

A flow-control valve placed in the exhaust line of a cylinder. It gives stable speed control and prevents runaway with overrunning loads.

FRL unit

Filter, regulator and lubricator group that conditions compressed air: removes particles and water, sets pressure and adds oil mist for pneumatic components.

Cutting speed

Surface speed of the workpiece or tool relative to the cutting edge, v = π·D·n/1000 in m/min. It depends mainly on tool and workpiece material.

ISO fit H7/g6

A clearance fit: hole tolerance H7 starts at nominal size, shaft tolerance g6 lies below it, guaranteeing a small clearance between shaft and hole.

Micrometer

Precision measuring instrument with a screw spindle, typically reading to 0.01 mm; used for external diameters and thicknesses with high accuracy.

Carnot efficiency

The maximum possible efficiency of a heat engine between two reservoirs: η = 1 − T_cold/T_hot, with absolute temperatures in kelvin.

Wind power equation

Power available in wind is P = ½ρAv³. Because it depends on the cube of wind speed, doubling wind speed gives eight times the power.

Transformer principle

Two coils on a common magnetic core transfer AC power; voltage ratio equals turns ratio V1/V2 = N1/N2, with nearly no power loss in an ideal transformer.

First-angle projection

European drawing convention: the object sits between observer and plane. The top view is placed below the front view and the left view to the right.

Geometric tolerance

Symbol on a drawing that limits form, orientation or position deviation (flatness, perpendicularity, position) relative to a datum, beyond size tolerance.

Gantt chart

A bar chart showing project tasks along a timeline, their duration, start and end dates and overlaps; used for planning and progress control.

Parametric CAD

Modelling approach where geometry is driven by dimensions and constraints; changing a parameter updates the model and associated drawings automatically.

G-code G01

CNC command for linear interpolation at a programmed feed rate F, moving the tool in a straight line to the specified coordinates.

Additive manufacturing

Production of parts layer by layer from a 3D model, using FDM, SLA or SLS. Suited to prototypes and complex geometries without specific tooling.