Year 12 Edexcel Engineering: Glossary of Key Terms & Quick Memorization Guide

📚 Year 12 Edexcel Engineering: Glossary of Key Terms & Quick Memorization Guide | 词汇术语速记指南

Mastering the precise vocabulary of engineering is essential for Year 12 Edexcel students: it sharpens your exam answers, enriches your technical reports, and builds a solid foundation for advanced study. This guide presents essential terms grouped by topic, each accompanied by a quick memory tip, so you can confidently recall definitions under pressure.

掌握精准的工程词汇对 Year 12 Edexcel 学生至关重要：它能让你的考试答案更精准、丰富你的技术报告，并为进阶学习打下坚实基础。本指南将按主题分组列出核心术语，每条都附上一个快速记忆窍门，帮助你在压力下也能自信地回忆起定义。

1. Introduction to Key Engineering Terminology | 工程关键术语简介

Before diving into calculations, it is crucial to understand the language of engineering. Terms like ‘system’, ‘component’ and ‘mechanism’ appear in almost every question. Visualising a bicycle can help: the frame is a structure, the chain and gears form a mechanism, and the entire bicycle represents a system.

在深入计算之前，理解工程语言至关重要。诸如“系统”、“组件”和“机构”这类术语几乎会出现在每道题中。想象一辆自行车会有帮助：车架是结构，链条和齿轮组成了机构，而整辆自行车则代表了一个系统。

Term (术语)	Definition (定义)	Memory Aid (记忆辅助)
System	A set of interrelated components working together to achieve a common goal.	Think ‘System = Set of parts with the Same aim’.
Subsystem	A smaller system that forms part of a larger system.	A car’s braking subsystem is part of the whole vehicle system.
Mechanism	An assembly of moving parts that perform a specific function, often involving force and motion transformation.	‘Mecha-‘ means moving; think of mechanical watch gears.

2. Forces and Moments | 力与力矩

A force is a push or pull that can cause an object to accelerate. The moment of a force, often called torque when dealing with rotation, is its turning effect about a pivot. Always specify the direction (clockwise or anticlockwise) when describing a moment; it is a vector quantity and marks are often lost for ignoring its directional nature.

力是一种推或拉，能使物体加速。力的力矩（在涉及转动时通常称为扭矩）是其绕支点的转动效应。描述力矩时一定要指明方向（顺时针或逆时针）；力矩是矢量，忽视方向性往往会丢分。

Resultant force (合力): The single force that has the same effect as all the original forces acting together. Tip: Replace several arrows with one equivalent arrow. (合力：与所有原始力共同作用效果相同的单一力。提示：用一根等效箭头替代多根箭头。)
Equilibrium (平衡): A state where the resultant force and the resultant moment on a body are both zero. Tip: A seesaw perfectly balanced – no movement, no turning. (平衡：物体所受合力与合力矩均为零的状态。提示：一个完美平衡的跷跷板——不移动、不转动。)
Reaction force (反作用力): The force exerted by a surface or support in response to a load, perpendicular to the contact surface. Tip: Table pushes back up on your book. (反作用力：表面或支撑物响应载荷而施加的力，垂直于接触面。提示：桌子向上推着你的书。)
Coefficient of friction (摩擦系数, μ): Ratio of frictional force to normal reaction. Tip: μ = F/R, like ‘My car’s tyres grip the Road’. (摩擦系数：摩擦力与法向反力的比值。提示：μ = F/R，就像“我车轮胎抓地”。)

Moment (M) = Force (F) × Perpendicular distance from pivot (d)

力矩 (M) = 力 (F) × 支点的垂直距离 (d)

3. Stress, Strain and Material Properties | 应力、应变与材料性能

Stress quantifies how much internal force is being distributed over a material’s cross‑sectional area, while strain measures the deformation relative to the original dimension. Never confuse stiffness (resistance to deformation) with strength (ability to withstand load without failure); a glass rod is stiff but not strong in tension.

应力量化了材料横截面上分布的内力大小，而应变则衡量相对于原始尺寸的变形量。切不可将刚度（抵抗变形的能力）与强度（在未破坏的情况下承受载荷的能力）混淆；一根玻璃棒很硬但在拉伸下并不强。

Term (术语)	Formula / Key point (公式/要点)	Memory Aid (记忆辅助)
Tensile stress (拉伸应力)	σ = F / A	Stress Stretches the Section (area).
Tensile strain (拉伸应变)	ε = ΔL / L₀ (no units, often %)	Strain is the Stretch ratio.
Young’s modulus (杨氏模量, E)	E = stress / strain (within limit)	Stiffness: steep slope on σ-ε graph.
Yield strength (屈服强度)	Stress at which plastic deformation begins.	Yield = You pass the elastic limit.
Toughness (韧性)	Energy absorbed before fracture (area under σ-ε curve).	Tough = absorbs a lot of energy; tough workout.
Hardness (硬度)	Resistance to surface indentation or scratching.	Hard to scratch a diamond.

4. Mechanical Power Transmission | 机械动力传递

Power transmission systems use gears, belts, chains and couplings to transfer rotational motion and torque. Gear ratio directly affects speed and torque; a small gear driving a large gear multiplies torque but reduces speed, which is why you climb hills in a lower gear on a bicycle.

动力传动系统使用齿轮、皮带、链条和联轴器来传递旋转运动和扭矩。齿轮比直接影响转速和扭矩；小齿轮驱动大齿轮会增大扭矩但减小转速，这就是骑自行车爬坡时要换到低档的原因。

Gear ratio (齿轮比): Teeth on driven gear / teeth on driver gear. Tip: Output teeth ÷ Input teeth. (齿轮比：从动齿轮齿数/主动齿轮齿数。提示：输出齿数÷输入齿数。)
Torque (扭矩, T): A measure of rotational force; T = F × r. Tip: Torque Turns the shaft. (扭矩：旋转力的量度；T = F × r。提示：扭矩转动轴。)
Shaft coupling (联轴器): Connects two shafts to transmit power, can be rigid or flexible. Tip: Couple = bring together. (联轴器：连接两根轴以传递动力，可为刚性或柔性。提示：Couple = 连接在一起。)
Chain drive vs. belt drive (链传动与带传动): Chains have positive engagement (no slip), belts can slip but are quieter and absorb shock. Tip: Chain = no slip; belt = quiet slip possible. (链传动具有正向啮合（无滑动），带传动可能打滑但噪音小、可吸收振动。提示：Chain 无滑动；belt 可能滑动但安静。)

5. Electronics and Circuit Theory | 电子学与电路理论

Understanding basic circuit quantities and components is vital for engineering students. Ohm’s law (V = I × R) is the anchor; think of it as ‘Voltage pushes Current through Resistance’. The distinction between analogue (continuously varying) and digital (discrete steps) signals appears in control systems and sensor analysis.

理解基本电路量和元器件对工科学生至关重要。欧姆定律（V = I × R）是基石；可以记作“电压推动电流通过电阻”。模拟信号（连续变化）与数字信号（离散阶跃）的区别会出现在控制系统和传感器分析中。

Symbol (符号)	Term (术语)	Unit (单位)	Memory Aid (记忆辅助)
V	Voltage (电压)	Volt (V)	Voltage = Electrical ‘push’.
I	Current (电流)	Ampere (A)	Current = flow of charge.
R	Resistance (电阻)	Ohm (Ω)	Resistance restricts current.
P	Power (功率)	Watt (W)	P = V × I; Power is product.

Analogue vs. Digital (模拟与数字): An analogue signal can take any value within a range, like a traditional vinyl record groove. A digital signal only takes discrete levels (0 or 1), like a CD’s pits and lands. (模拟信号可以在一个范围内取任意值，如同传统黑胶唱片的沟槽。数字信号只取离散电平（0或1），如同光盘的坑与岸。)

6. Manufacturing Processes | 制造工艺

Manufacturing transforms raw materials into finished products through processes such as casting, forming, machining and joining. The choice of process depends on material, production volume, tolerance and surface finish. A key concept is ‘subtractive vs additive’ manufacturing: machining removes material, while 3D printing adds it layer by layer.

制造通过铸造、成形、机械加工和连接等工艺将原材料转化为成品。工艺选择取决于材料、产量、公差及表面光洁度。一个关键概念是“减材与增材”制造：机械加工移除材料，而 3D 打印则逐层添加材料。

Casting (铸造): Pouring molten metal into a mould cavity. Tip: Think of making a chocolate shape using a mould. (铸造：将熔融金属浇入模具型腔。提示：想象用模具做巧克力形状。)
Forging (锻造): Shaping metal using compressive forces, often hot, to refine grain structure. Tip: Blacksmith hammering hot iron – increases strength. (锻造：用压力、通常是热压使金属成型，以细化晶粒结构。提示：铁匠锤打热铁——提高强度。)
Milling / Turning (铣削/车削): Milling uses a rotating cutter to remove material from a stationary workpiece; turning rotates the workpiece against a fixed cutting tool. Tip: The tool moves around the workpiece in milling; the workpiece spins in turning. (铣削：旋转刀具从固定工件上切除材料；车削：工件旋转，固定刀具切削。提示：铣削是刀具绕工件，车削是工件旋转。)
Additive manufacturing (增材制造): 3D printing builds objects layer by layer from digital models. Tip: Add layer upon layer. (增材制造：3D 打印根据数字模型逐层构建物体。提示：一层一层地添加。)

7. Health and Safety Terms | 健康与安全术语

Engineers must design and operate within a culture of safety. Hazard identification, risk assessment and the use of personal protective equipment (PPE) are not optional extras but legal requirements under UK regulations such as the Health and Safety at Work Act 1974. A hazard is the potential source of harm; risk is the likelihood of that harm occurring.

工程师必须在安全文化下进行设计和操作。危险识别、风险评估及个人防护装备（PPE）的使用并非可选项，而是根据英国《1974 年工作健康与安全法案》等法规的法定要求。危害是潜在的伤害源；风险则是该伤害发生的可能性。

Hazard (危害): Anything that may cause injury or ill health (e.g., rotating shaft, hot surface). (危害：任何可能导致伤害或健康损害的事物（如旋转轴、热表面）。)
Risk (风险): The chance, high or low, that somebody will be harmed by the hazard. (风险：某人被该危害伤害的机会，不论高低。)
PPE (个人防护装备): Equipment worn to minimise exposure to hazards (gloves, goggles, hard hat). Tip: The last line of defence. (PPE：为最大程度降低危害暴露而穿戴的装备（手套、护目镜、安全帽）。提示：最后一道防线。)
COSHH (有害物质控制法规): Control of Substances Hazardous to Health – requires assessment and control of chemicals, fumes, dusts. (COSHH：《有害健康物质控制法规》——要求对化学品、烟雾、粉尘进行评估和控制。)
Risk assessment (风险评估): 5-step process: identify hazards, decide who may be harmed, evaluate risks and precautions, record findings, review. (风险评估：五步法：识别危害、确定可能受伤害的人员、评估风险与预防措施、记录结果、审核。)

8. Standards and Tolerances | 标准与公差

Interchangeability and quality rely on agreed standards (BS, ISO) and precise tolerances. A tolerance defines the permissible variation in a dimension; without it, parts would not fit together in assembly. Bilateral tolerance allows variation in both directions from a nominal size, while unilateral tolerance permits variation in only one direction.

互换性和质量依赖于公认的标准（BS、ISO）和精确的公差。公差定义了尺寸允许的变动范围；没有它，零件装配时便无法配合。双边公差允许偏离公称尺寸的双向变动，而单边公差只允许单方向变动。

Nominal size (公称尺寸): The intended or named dimension, e.g., 20 mm diameter. (公称尺寸：预期或命名的尺寸，例如直径 20 mm。)
Upper deviation / Lower deviation (上偏差/下偏差): Maximum and minimum limits minus the nominal size. (上偏差/下偏差：最大极限和最小极限减去公称尺寸。)
Fits: Clearance, Interference, Transition (配合：间隙、过盈、过渡): Clearance fit always leaves a gap (shaft smaller than hole); interference fit requires force to assemble (shaft larger than hole); transition fit can be either a small clearance or interference. (间隙配合始终留有间隙（轴小于孔）；过盈配合需要用力压装（轴大于孔）；过渡配合可能为小间隙或小过盈。)
BS 8888 (英国标准 8888): The UK standard for technical product specification and documentation. (BS 8888：英国技术产品规范与文档标准。)

9. Fluid Mechanics Basics | 流体力学基础

Fluid mechanics examines the behaviour of liquids and gases at rest or in motion. The continuity equation and Bernoulli’s principle are central to understanding pipe flow, aerodynamics and hydraulic systems. For incompressible flow, volume flow rate remains constant: A₁v₁ = A₂v₂.

流体力学研究液体和气体在静止或运动时的行为。连续性方程和伯努利原理对于理解管道流动、空气动力学和液压系统至关重要。对于不可压缩流体，体积流量保持不变：A₁v₁ = A₂v₂。

Continuity equation: A₁v₁ = A₂v₂ (Q = Av, flow rate constant)

连续性方程：A₁v₁ = A₂v₂ (Q = Av，流量恒定)

Laminar flow (层流): Smooth, orderly fluid motion in parallel layers; no mixing. Tip: Layers are Laminar. (层流：平滑、有序的平行层流体运动；无混合。提示：Layer 是层流。)
Turbulent flow (湍流): Chaotic, irregular motion with eddies and mixing. Tip: Turbulent = trouble, messy. (湍流：混乱、不规则的带有涡流和混合的运动。提示：湍流 = 混乱、一团糟。)
Bernoulli’s principle (伯努利原理): An increase in fluid velocity occurs simultaneously with a decrease in pressure or potential energy. Tip: Fast air = low pressure; aeroplane wing lift. (伯努利原理：流体速度增加的同时，压力或势能会降低。提示：快速空气 = 低压；飞机机翼升力。)
Hydraulic multiplication (液压放大): Using Pascal’s law: P = F/A; a small force on a small piston can create a large force on a larger piston. Tip: Car brake system – foot on pedal stops a heavy car. (液压放大：运用帕斯卡定律：P = F/A；小活塞上的小力可在大活塞上产生大力。提示：汽车制动系统——脚踩踏板能刹停重车。)

10. Engineering Design Process | 工程设计流程

The design process is iterative, not linear. After identifying a need, engineers generate a design brief, research, develop concepts, prototype, test and refine. The Edexcel specification expects you to understand modelling techniques, technical drawings (orthographic projection, isometric) and the role of CAD/CAM in shortening development cycles.

设计流程是迭代性的，而非线性的。在确定需求后，工程师会制定设计概要、进行研究、开发概念、制作原型、测试并优化。Edexcel 考纲要求你理解建模技术、工程图（正投影、等轴测图）以及 CAD/CAM 在缩短开发周期方面的作用。

Design brief (设计概要): A clear statement of the problem and the objectives. (设计概要：对问题及目标的清晰描述。)
Specification (设计规范): A detailed list of requirements and constraints (size, weight, cost, materials). (设计规范：包含各项要求与约束条件的详细列表（尺寸、重量、成本、材料）。)
CAD (计算机辅助设计): Software for creating, modifying and optimising 3D models. (CAD：用于创建、修改和优化 3D 模型的软件。)
Rapid prototyping (快速原型制作): Quickly fabricating a scale model or prototype using 3D printing or similar. (快速原型制作：使用 3D 打印或类似技术快速制造比例模型或原型。)

11. Energy and Thermodynamics | 能量与热力学

Energy cannot be created or destroyed, only transferred or converted – this is the first law of thermodynamics. In engineering, we track energy flows using Sankey diagrams and calculate efficiency as useful output energy divided by total input energy. Always express efficiency as a decimal or percentage; a machine cannot be 100% efficient due to friction and heat loss.

能量既不能被创造也不能被消灭，只能被转移或转化——这就是热力学第一定律。在工程中，我们使用桑基图追踪能量流，并计算效率 = 有用输出能量 / 总输入能量。效率始终以小数或百分比表示；由于摩擦和热损失，机器不可能达到 100% 的效率。

Efficiency (η) = Useful output power (or energy) / Total input power (or energy)

效率 (η) = 有用输出功率（或能量）/ 总输入功率（或能量）

Conduction, convection, radiation (传导、对流、辐射): Three modes of heat transfer. Tip: Solid hand holding hot mug = conduction; boiling water rising = convection; sun warming face = radiation. (热传递三种方式。提示：手握热杯是传导；沸水翻腾是对流；阳光暖面是辐射。)
Thermal conductivity (导热系数, k): A material’s ability to conduct heat; high k means good conductor. (材料导热能力；高 k 表示良导体。)
Specific heat capacity (比热容, c): Energy required to raise 1 kg of a substance by 1°C. (将 1 kg 物质升高 1°C 所需的能量。)
Latent heat (潜热): Energy absorbed or released during phase change without temperature change. (相变时无温度变化所吸收或释放的能量。)

12. Quick Memory Aids and Mnemonics | 快速记忆辅助与助记符

Use acronyms, rhyming and visual storytelling to lock in challenging terms. For instance, for the stress-strain curve stages, remember ‘Peel Your UTS Apples Thoroughly’ – Proportional limit, Yield point, Ultimate Tensile Strength, Fracture. For the order of drawing sizes (A0, A1, A2…), ‘Always Offer A Simple Tea’ – each step halves the previous area.

运用首字母缩略词、押韵和视觉故事来牢记难记的术语。例如，对于应力-应变曲线的阶段，记住“请剥开你的 UTS 苹果彻底”——比例极限、屈服点、极限抗拉强度、断裂。对于图纸尺寸顺序（A0、A1、A2…），“总给杯茶” – 每一步都是前一步面积的一半。

For Ohm’s Law triangle: “Virus I Risk” – cover the one you need: V on top, I and R on bottom. (欧姆定律三角：“病毒我危险”——盖住你需要的那一个：V 在上，I 和 R 在下。)
For the 4 stroke engine cycle: “Suck, Squeeze, Bang, Blow” – Induction, Compression, Power, Exhaust. (四冲程发动机循环：“吸、压、爆、排”——进气、压缩、做功、排气。)
For differentiate between accuracy and precision: Accuracy is hitting the bullseye (Closeness to true value); Precision is grouping the darts tightly (Consistency). (区分准确度与精密度：准确度是命中靶心（接近真值）；精密度是飞镖集中在一起（一致性）。)
For remembering modulus meanings: Young’s modulus – stretches; Shear modulus – twists; Bulk modulus – compresses. (记忆模量含义：杨氏模量–拉伸；剪切模量–扭转；体积模量–压缩。)

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Year 12 Edexcel Engineering: Glossary of Key Terms & Quick Memorization Guide | 词汇术语速记指南