📚 Key Terminology Quick-Memorisation Guide for WJEC Pre-U Engineering | Pre-U WJEC 工程：词汇术语速记指南
Welcome to this quick-memorisation guide for WJEC Pre-U Engineering. Mastering the precise terminology is half the battle in technical examinations. This article breaks down essential engineering vocabulary by topic, providing clear definitions, memory aids, and contextual examples to help you recall terms under pressure.
欢迎阅读 WJEC Pre-U 工程术语速记指南。掌握准确术语是应对技术类考试成功的一半。本文按主题分解必备工程词汇，提供清晰定义、记忆技巧和情境示例，帮助你在压力下快速回忆。
1. Mechanics of Materials | 材料力学
In materials science, quantities often come in pairs: stress with strain, elastic with plastic. Knowing the Greek symbols and formulas is vital for calculations and graph interpretation.
在材料科学中，物理量常成对出现：应力与应变、弹性与塑性。熟记希腊字母符号和公式对计算和图形判读至关重要。
| Term | Definition | 中文 | Memory Aid |
|---|---|---|---|
| Stress (σ) | Force per unit area, σ = F/A | 应力：单位面积上的力 | 'Sigma' starts with S like 'Stress' |
| Strain (ε) | Extension per original length, ε = ΔL/L₀ | 应变：伸长量与原长之比 | 'Epsilon' for 'Elongation' |
| Young's Modulus (E) | E = σ / ε (within the linear elastic region) | 杨氏模量：弹性阶段内应力与应变之比 | Think 'E' for 'Elastic stiffness' |
| Poisson's Ratio (ν) | Negative lateral strain / axial strain | 泊松比：负横向应变/轴向应变 | 'Nu' for 'Narrowing' when stretched |
| Shear Stress (τ) | Force parallel to area, τ = F/A | 剪应力：平行于面积的力 | 'Tau' looks like a T-ruler for 'Tangential' |
imit marks the point beyond which the material will no longer return to its original shape – it enters the plastic region where permanent deformation occurs. Hooke's Law (F = kx) applies only up to this limit.
弹性极限标记着材料不再恢复原形的临界点——此后进入塑性区域，发生永久变形。胡克定律 (F = kx) 仅在此极限内有效。
2. Material Properties | 材料性能
Selecting the right material for an engineering application depends on understanding descriptors like hardness, toughness, ductility and brittleness. Misinterpreting these can lead to design failure.
为工程应用选择合适的材料，有赖于理解硬度、韧性、延展性与脆性等术语。误解这些可能导致设计失败。
| Term | Definition | 中文 | Memory Aid |
|---|---|---|---|
| Hardness | Resistance to indentation or scratching | 硬度：抵抗压入或划伤的能力 | 'Hard' to scratch |
| Toughness | Energy absorbed before fracture (area under stress-strain curve) | 韧性：断裂前吸收的能量（应力-应变曲线下面积） | 'Tough' materials absorb impact |
| Ductility | Ability to be drawn into a wire or undergo large plastic strain | 延展性：可拉成丝或承受大塑性应变的能力 | 'Duct' = tube, wire – stretchy |
| Brittleness | Little or no plastic deformation before fracture | 脆性：断裂前几乎无塑性变形 | 'Brittle' like glass – snap without warning |
| Yield Strength | Stress at which plastic deformation begins | 屈服强度：塑性变形开始时的应力 | 'Yield' = give way |
| Ultimate Tensile Strength (UTS) | Maximum stress a material can withstand while being stretched | 极限抗拉强度：材料被拉伸时能承受的最大应力 | 'Ultimate' = final peak on the curve |
A common exam pitfall is confusing strength with toughness. Strength is about how much load it can carry; toughness is about how much energy it can absorb. Think of a ceramic – very strong but not tough.
一个常见的考试陷阱是将强度与韧性混淆。强度关乎能承受多大载荷，韧性关乎能吸收多少能量。想想陶瓷——强度很高但韧性很差。
3. Manufacturing Processes | 制造工艺
Manufacturing vocabulary describes how raw materials are transformed into finished components. Each process has a distinct effect on material structure and suitable applications.
制造工艺词汇描述如何将原材料转变为成品零件。每种工艺对材料结构有独特影响，并适用于不同场合。
| Term | Definition | 中文 | Memory Aid |
|---|---|---|---|
| Casting | Pouring molten metal into a mould cavity | 铸造：将熔融金属浇入模具型腔 | 'Cast' a shape like casting a spell – it takes form |
| Forging | Shaping metal using compressive forces, often hot | 锻造：用压缩力成形金属，常加热进行 | 'Forge' = force – hammering metal |
| Extrusion | Forcing material through a die to create a fixed cross-section profile | 挤压：将材料强制穿过模具形成固定截面形状 | Like squeezing toothpaste – 'exit' through a die |
| Welding | Joining materials by melting the interface, often with a filler | 焊接：通过熔化接合处实现连接，常添加填充料 | 'Weld' = 'well' joined – fuses together |
| Injection Moulding | Molten polymer injected into a cooled mould under pressure | 注塑：将熔融聚合物在压力下注入冷却模具 | 'Inject' medicine into a 'mould' |
| CNC Machining | Computer numerical control – automated cutting, drilling, milling | 数控加工：计算机数字控制——自动切削、钻孔、铣削 | 'Computer' tells 'Numerical' tool where to go |
When describing why a process is chosen, always link it to the desired properties: casting for complex geometries, forging for enhanced grain structure and strength, extrusion for long continuous profiles.
描述为何选用某种工艺时，务必将其与所需性能联系起来：铸造用于复杂几何形状，锻造改善晶粒结构并提高强度，挤压用于长条形连续截面。
4. Thermodynamics and Heat Transfer | 热力学与传热
Engineering thermodynamics deals with energy, work, and heat. The three heat transfer modes – conduction, convection and radiation – appear regularly, as do terms like specific heat capacity and thermal expansion.
工程热力学研究能量、功与热量。三种传热方式——传导、对流和辐射——反复出现，比热容和热膨胀等术语亦然。
| Term | Definition | 中文 | Memory Aid |
|---|---|---|---|
| Conduction | Heat transfer through a solid by molecular vibration, described by Fourier's Law: Q̇ = -kA(dT/dx) | 热传导：通过固体分子振动传递热量，遵循傅里叶定律 | 'Conduct' like a conductor baton – direct contact |
| Convection | Heat transfer via fluid movement; Newton's Law of Cooling: Q̇ = hA ΔT | 对流：通过流体运动传热；牛顿冷却定律 | 'Convection' current in a pot of water |
| Radiation | Electromagnetic wave emission; Stefan-Boltzmann: Q̇ = εσAT⁴ | 辐射：电磁波发射；斯特藩-玻尔兹曼定律 | Sun 'radiates' across vacuum |
| Specific Heat Capacity (c) | Energy to raise 1 kg by 1 K: Q = mcΔT | 比热容：1 kg 物质升温 1 K 所需能量 | 'Capacity' to absorb heat |
| Thermal Expansion | ΔL = αL₀ΔT (linear); area and volume expansions are proportional | 热膨胀：线膨胀公式，面积和体积膨胀按比例计算 | Metals 'expand' in summer heat |
| Latent Heat | Energy absorbed/released during phase change at constant temperature (L) | 潜热：相变时在恒温下吸收或释放的能量 | 'Latent' = hidden, temperature stays flat |
Note that the 'heat transfer coefficient' h has units W/m²K, and it differs greatly between natural and forced convection. In calculations, always list the mode(s) involved before selecting the appropriate formula.
注意，“对流传热系数” h 的单位为 W/m²K，自然对流与强制对流的数值差异很大。计算时，务必先列出涉及的传热模式，再选择合适的公式。
5. Electrical and Electronic Principles | 电学与电子原理
Electrical terminology underpins everything from simple circuits to complex control systems. Ohm's Law, Kirchhoff's rules, and component descriptors are fundamental.
电学术语是简单电路到复杂控制系统的基础。欧姆定律、基尔霍夫定则以及元件描述词都是基石。
| Term | Definition | 中文 | Memory Aid |
|---|---|---|---|
| Resistance (R) | V = IR; opposition to current, unit Ohm (Ω) | 电阻：对电流的阻碍，单位欧姆 (Ω) | 'Resist' the flow |
| Capacitance (C) | Q = CV; stores charge, unit Farad (F) | 电容：储存电荷的能力，单位法拉 (F) | 'Capacitor' = a tiny 'capacity' tank for charge |
| Inductance (L) | V = L (dI/dt); opposes change in current, unit Henry (H) | 电感：阻碍电流变化，单位亨利 (H) | Coil 'induces' back EMF |
| Kirchhoff's Voltage Law (KVL) | Sum of voltages around a closed loop = 0 | 基尔霍夫电压定律：闭合回路中电压代数和为零 | 'Loop' rule – rises = drops |
| Kirchhoff's Current Law (KCL) | Sum of currents entering a node = sum leaving | 基尔霍夫电流定律：流入节点的电流之和等于流出之和 | 'Junction' rule – what goes in must come out |
| Power (P) | P = IV = I²R = V²/R; unit Watt (W) | 电功率：单位瓦特 (W) | 'Power' is voltage times current |
In AC circuits, terms like impedance (Z), reactance (X), and phase angle become important. Remember: capacitors cause current to lead voltage, while inductors cause current to lag.
在交流电路中，阻抗 (Z)、电抗 (X) 和相位角等术语变得重要。记住：电容使电流超前电压，电感使电流滞后。
6. Mechanical Systems | 机械系统
Mechanical systems vocabulary revolves around motion, forces, and energy transfer. Gear trains, linkages, and cams each have their own language describing advantages and efficiency.
机械系统词汇围绕运动、力和能量传递展开。齿轮系、连杆机构和凸轮各自拥有描述其优势和效率的专门用语。
| Term | Definition | 中文 | Memory Aid |
|---|---|---|---|
| Mechanical Advantage (MA) | MA = Load / Effort (ideal MA = distance ratio) | 机械利益：负载与施力之比（理想机械利益等于速比） | 'Advantage' = you get more out than you put in |
| Velocity Ratio (VR) | VR = distance moved by effort / distance moved by load | 速比：施力点移动距离与负载移动距离之比 | 'Ratio' of speeds |
| Efficiency (η) | η = (output work / input work) × 100% = MA / VR | 效率：输出功与输入功之比 | Never over 100% – friction always steals some |
| Gear Ratio | Ratio of teeth on driven gear to teeth on driving gear; affects torque and speed | 齿轮比：从动轮齿数与主动轮齿数之比，影响扭矩和转速 | More teeth on driven = more torque, less speed |
| Cam Follower | A component that traces the profile of a cam to produce reciprocating motion | 凸轮从动件：与凸轮廓线接触，产生往复运动的零件 | 'Follows' the cam's shape |
| Torque (τ) | τ = F × r (perpendicular lever arm), unit N·m | 扭矩：力乘以力臂长度，单位 N·m | 'Torque' turns things |
When analysing linkages, be able to identify four-bar chain, slider-crank, and quick-return mechanisms. The
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