📚 Year 12 OCR Engineering: A Quick Memory Guide to Key Terms | 工程学科：关键词汇术语速记指南
Mastering the specialist vocabulary of engineering is essential in Year 12 OCR coursework and exams. This rapid memory guide presents core terms grouped by topic, each explained in clear English and Chinese with a memorable hint. Use it to build confidence in definitions, processes and symbols.
掌握工程学科的专业词汇对Year 12 OCR的学习和考试至关重要。这份速记指南将核心术语按主题分组，每个术语都用清晰的英文和中文解释，并配上记忆提示。用它来增强你对定义、工艺和符号的信心。
1. Material Properties Terms | 材料属性术语
Ductility describes the ability of a material to be drawn into a wire under tensile force without breaking. Think of copper being pulled into thin electrical wires — ‘ductile’ sounds like ‘duct’ (a channel you can pull through).
延展性 描述材料在拉力作用下被拉成丝而不断裂的能力。联想铜被拉成细电线 — ‘ductile’ 听起来像管道，可拉伸穿过。
Malleability is the capacity of a material to deform under compressive stress, often by hammering or rolling into thin sheets. Gold leaf is the classic example; ‘malleus’ means hammer in Latin.
可锻性 是材料在压应力下通过锤击或轧制变形成薄板的能力。金箔是典型例子；’malleus’ 在拉丁语中意为锤子。
Hardness measures resistance to surface indentation or scratching. Diamond is the hardest natural material, used to cut glass. Remember hardness tests like Brinell or Vickers — they push an indenter into the surface.
硬度 衡量材料抵抗表面压痕或划伤的能力。钻石是最硬的天然材料，用于切割玻璃。记住布氏硬度或维氏硬度测试——将压头压入表面。
Toughness indicates how much energy a material can absorb before fracturing. It combines strength and ductility; polycarbonate (safety glasses) is very tough. Not the same as hardness — tough materials resist impact.
韧性 表示材料在断裂前能吸收多少能量。它结合了强度和延展性；聚碳酸酯（安全眼镜）非常坚韧。韧性与硬度不同——韧性材料抗冲击。
Brittleness is the opposite of toughness: a brittle material fractures suddenly with little plastic deformation. Glass and cast iron are brittle. Mnemonic: ‘brittle’ snaps like a biscuit.
脆性 与韧性相反：脆性材料几乎不发生塑性变形就突然断裂。玻璃和铸铁具有脆性。助记：“脆”得像饼干一样折断。
Elasticity is the property of returning to original shape after a load is removed. Rubber bands and steel springs exhibit elasticity within their elastic limit. Hooke’s law describes this linear behaviour.
弹性 是载荷去除后恢复原始形状的性质。橡皮筋和钢弹簧在弹性极限内表现出弹性。胡克定律描述了这种线性行为。
2. Mechanical Properties & Stress–Strain | 力学性能与应力–应变
Stress (σ) is internal force per unit area, measured in pascals (Pa). σ = F/A, where F is force and A the cross-sectional area. Imagine stress as ‘force intensity’ inside the material.
应力 (σ) 是单位面积上的内力，单位为帕斯卡 (Pa)。σ = F/A，F 为力，A 为横截面积。把应力想象成材料内部的“力密集度”。
Strain (ε) is the extension per unit original length, a dimensionless ratio. ε = ΔL/L₀. Strain shows how much a material stretches relative to its starting length.
应变 (ε) 是单位原始长度的伸长量，无量纲比值。ε = ΔL/L₀。应变显示材料相对于起始长度的伸长程度。
Young’s Modulus (E) measures stiffness: the ratio of stress to strain in the elastic region. E = σ/ε. A high modulus means the material resists stretching. Steel has a high E; rubber has a low E.
杨氏模量 (E) 衡量刚度：弹性区域内应力与应变的比值。E = σ/ε。高模量意味着材料抗拉伸。钢的 E 值高；橡胶的 E 值低。
Hooke’s Law: σ = E × ε
Yield strength is the stress at which a material begins to deform permanently. Beyond this point, plastic deformation occurs. On a stress–strain graph, it is where the curve deviates from straight.
屈服强度 是材料开始发生永久变形的应力。超过此点，塑性变形发生。在应力–应变曲线图上，它是曲线偏离直线的地方。
Ultimate tensile strength (UTS) is the maximum stress a material can withstand while being stretched before necking. It is the peak of the engineering stress–strain curve.
抗拉强度极限 (UTS) 是材料在拉伸时颈缩前能承受的最大应力。它是工程应力–应变曲线的峰值。
Stiffness depends on both Young’s Modulus and geometry. A thicker beam is stiffer than a thin one of the same material. Stiffness resists deflection under load, different from strength.
刚度 取决于杨氏模量和几何形状。相同材料的较厚梁比薄梁刚度高。刚度抵抗载荷下的挠度，与强度不同。
3. Manufacturing Processes | 制造工艺
Casting involves pouring molten metal into a mould cavity where it solidifies. Sand casting uses a expendable sand mould; die casting uses a reusable metal mould. Remember the ‘liquid → solid’ transformation.
铸造 将熔融金属倒入模腔并使其凝固。砂型铸造使用一次性砂型；压铸使用可重复使用的金属模。记住“液态→固态”转变。
Forging shapes metal by applying compressive forces, often with a hammer or press. It refines grain structure and improves strength. A blacksmith forging a horseshoe is a classic image.
锻造 通过施加压缩力（常用锤或压力机）使金属成形，能细化晶粒并提高强度。铁匠锻造马蹄铁是经典画面。
Welding joins materials by melting the workpieces and adding a filler, causing coalescence. MIG, TIG and arc welding are common. Think of ‘welding’ as fusing with intense heat.
焊接 通过熔化母材并添加填充材料实现连接，使工件熔合。MIG、TIG 和电弧焊常见。把“焊接”想成用高温熔合。
Brazing uses a filler metal with a melting point above 450°C but below the melting point of the base metals. Capillary action draws the filler into the joint. Stronger than soldering.
钎焊 使用熔点高于450°C但低于母材熔点的填充金属。毛细作用将填充料吸入接头。强度高于软钎焊。
Soldering joins components with a filler metal melting below 450°C, often using a soldering iron. Used extensively in electronics. Mnemonic: ‘solder’ is soft, lower temperature.
软钎焊 用熔点低于450°C的填充金属连接元件，常使用烙铁。广泛用于电子行业。助记：’solder’ 较软，温度较低。
Turning is a machining process where a cutting tool removes material from a rotating workpiece on a lathe. Produces cylindrical shapes. Visualise shaping a wooden leg on a lathe.
车削 是一种机加工，车刀在车床上从旋转的工件上去除材料。生产圆柱形状。想象在车床上车削木制桌腿。
Milling uses a rotating multi-point cutter to remove material as the workpiece moves. Can create flat surfaces, slots and complex profiles. The cutter rotates, not the workpiece (usually).
铣削 使用旋转多刃铣刀，工件移动时去除材料。可加工平面、槽和复杂轮廓。通常是刀具旋转而非工件。
4. Electronics Terminology | 电子学术语
Voltage (V) is the electrical potential difference that drives current around a circuit, measured in volts (V). Think of voltage as ‘electrical pressure’ pushing electrons.
电压 (V) 是驱动电流在电路中流动的电势差，单位为伏特 (V)。可把电压看作推动电子的“电压力”。
Current (I) is the rate of flow of electric charge, measured in amperes (A). I = Q/t. Conventional current flows from positive to negative, although electron flow is opposite.
电流 (I) 是电荷流动的速率，单位为安培 (A)。I = Q/t。虽然电子流方向相反，但常规电流从正极流向负极。
Resistance (R) opposes current, measured in ohms (Ω). R = V/I. A resistor converts electrical energy into heat. Think of it as a narrow pipe restricting water flow.
电阻 (R) 阻碍电流，单位为欧姆 (Ω)。R = V/I。电阻器将电能转化为热能。可想象成限制水流量的窄管。
Ohm’s Law: V = I × R
Power (P) is the rate of energy transfer, measured in watts (W). P = V × I. In a resistor, power is dissipated as heat; in a motor, it becomes mechanical output.
功率 (P) 是能量转换的速率，单位为瓦特 (W)。P = V × I。在电阻器中功率以热量散逸；在电机中则变为机械输出。
Diode allows current to flow in one direction only — forward biased. It has a low resistance in forward direction and very high in reverse. Used for rectification. Think of a one-way valve.
二极管 只允许电流单向流动 — 正向偏置时导通。正向电阻低，反向电阻极高。用于整流。想象一个单向阀。
Transistor is a semiconductor device that can amplify or switch electronic signals. A small base current controls a larger collector–emitter current. Key component in amplifiers and logic gates.
晶体管 是能放大或开关电子信号的半导体器件。小的基极电流控制更大的集电极–发射极电流。是放大器和逻辑门的关键元件。
5. Structures and Forces | 结构与力
Load is any force applied to a structure. Dead loads are permanent (self-weight), live loads are variable (people, vehicles). A beam must be designed for the worst combination.
载荷 是施加在结构上的任何力。恒载是永久的（自重），活载是变化的（人、车辆）。梁必须按最不利组合设计。
Bending moment at a section of a beam is the sum of moments on one side, causing the beam to bend. Maximum bending moment often occurs at mid-span of a simply supported beam with a central load.
弯矩 是梁某截面一侧的力矩总和，使梁弯曲。简支梁承受中心载荷时，最大弯矩通常出现在跨中。
Shear force at a section is the algebraic sum of vertical forces to one side. It tries to shear the beam. The shear force diagram jumps at point loads; remember ‘shear = sliding’.
剪力 是截面一侧竖向力的代数和，试图将梁剪断。剪力在集中力处突变；记住 “shear = 滑动”。
Deflection is the displacement of a structural element under load. Excessive deflection can cause cracking or discomfort. Stiffness limits deflection; remember ‘deflect = bend down’.
挠度 是结构构件在载荷下的位移。过大的挠度可引起开裂或不舒适。刚度限制挠度；记住 “deflect = 向下弯曲”。
Factor of Safety is the ratio of the material’s failure stress to the allowable design stress. It provides a margin for uncertainties. A typical factor for structural steel is around 1.6.
安全系数 是材料破坏应力与允许设计应力之比。它为不确定性提供余量。结构钢的典型安全系数约为1.6。
Stress concentration occurs at sharp corners, holes or sudden changes in cross-section, where stress is magnified. Fillets reduce stress concentration. Remember ‘stress raisers’ require smooth transitions.
应力集中 在尖角、孔洞或截面突变处发生，应力被放大。圆角可减小应力集中。记住“应力提升点”需要平滑过渡。
6. Materials Classification | 材料分类
Ferrous metals contain iron as the main constituent. Examples: mild steel (low carbon), cast iron (high carbon). Most are magnetic and rust unless protected. Mnemonic: ‘Ferrous’ starts with Fe (iron).
铁金属 以铁为主要成分。例如：低碳钢（低碳），铸铁（高碳）。大多具磁性，若无保护会生锈。助记：“Ferrous”以 Fe（铁）开头。
Non-ferrous metals do not contain iron. Aluminium, copper, zinc and titanium are common. They resist corrosion well and are often lighter. Aluminium is widely used in aerospace.
非铁金属 不含铁。常见的有铝、铜、锌和钛。它们耐腐蚀性好，通常更轻。铝广泛用于航空航天。
Alloys are mixtures of a metal with other elements to enhance properties. Steel (iron + carbon), brass (copper + zinc) and bronze (copper + tin). Think of ‘alloy’ as a metallic cocktail.
合金 是金属与其他元素的混合物，以改善性能。钢（铁+碳）、黄铜（铜+锌）和青铜（铜+锡）。把“合金”想象成金属鸡尾酒。
Polymers are long-chain molecules. Thermoplastics (e.g. ABS, nylon) soften when heated and can be remoulded. Thermosets (e.g. epoxy) set permanently. Remember ‘thermo-soft’ vs ‘thermo-set’.
聚合物 是长链分子。热塑性塑料（如 ABS、尼龙）受热软化并可重塑。热固性塑料（如环氧树脂）永久固化。记住“热软”与“热固”。
Ceramics are inorganic, non-metallic solids like alumina, glass and silicon carbide. They are hard, brittle and have high melting points. Used for furnace linings and cutting tools.
陶瓷 是无机非金属固体，如氧化铝、玻璃和碳化硅。它们硬而脆，熔点高。用于炉衬和切削刀具。
Composites combine two or more distinct materials to achieve superior properties. Fibreglass (glass fibres in polymer) and carbon fibre reinforced plastic (CFRP) are examples. The matrix binds the reinforcement.
复合材料 将两种或多种不同材料结合以获得优异性能。玻璃纤维（聚合物中加玻璃纤维）和碳纤维增强塑料 (CFRP) 是例子。基体粘结增强体。
Smart materials respond to external stimuli: shape memory alloys (SMA) return to a preset shape when heated; piezoelectric materials generate voltage under stress. Remember ‘smart’ = responds to environment.
智能材料 对外部刺激作出响应：形状记忆合金 (SMA) 受热时恢复预设形状；压电材料受力时产生电压。记住“智能”= 响应环境。
7. Health & Safety in Engineering | 工程健康与安全
Hazard is anything with the potential to cause harm, e.g. a rotating blade or toxic fume. A hazard is inherent; risk is the likelihood of harm actually occurring.
危险源 (Hazard) 是任何可能造成伤害的事物，如旋转刀片或有毒烟雾。危险源本身存在；风险则是伤害实际发生的可能性。
Risk combines the probability of an event and its consequences. Risk = likelihood × severity. Risk assessment aims to reduce risk to an acceptable level.
风险 (Risk) 结合了事件发生的概率及其后果。风险 = 可能性 × 严重程度。风险评估旨在将风险降至可接受水平。
PPE (Personal Protective Equipment) includes safety glasses, hard hats, steel-toe boots, gloves and ear defenders. PPE is the last line of defence after engineering controls.
PPE (个人防护装备) 包括安全眼镜、安全帽、钢头鞋、手套和耳罩。PPE 是工程控制措施后的最后一道防线。
COSHH stands for Control of Substances Hazardous to Health. It requires employers to assess and control exposure to chemicals, dust and fumes. Always check the safety data sheet (SDS).
COSHH 代表有害健康物质控制。它要求雇主评估并控制对化学品、粉尘和烟雾的接触。始终查阅安全数据表 (SDS)。
Risk assessment involves identifying hazards, deciding who might be harmed, evaluating risks and recording preventive measures. The five-step process is a key memory item.
风险评估 包括识别危险源、确定谁会受伤害、评估风险并记录预防措施。五步流程是重要记忆点。
Manual handling refers to lifting, carrying or moving loads by hand. Correct technique: keep the load close, bend the knees, and avoid twisting. Mechanical aids should be used where possible.
人力搬运 指用手提举、搬运或移动重物。正确技术：使负荷靠近身体，弯膝，避免扭转。应尽可能使用机械辅助。
8. Engineering Drawing & Symbols | 工程制图与符号
Orthographic projection uses multiple 2D views (front, top, side) to fully describe a 3D object. Follows British Standards (BS 8888). Remember: each view is aligned, not in perspective.
正投影 使用多个二维视图（前、俯、侧）来完整描述三维物体。遵循 BS 8888 标准。记住：各视图对齐，不采用透视。
Isometric drawing is a pictorial representation where all three axes are equally foreshortened, at 120° to each other. Provides a 3D-like view. Use a 30°/30° set square.
等轴测图 是一种图形表示，三个轴等距缩短且互成120°。呈现三维类似视图。使用30°/30°三角板绘制。
Dimensioning specifies the exact size and location of features. Extension lines, dimension lines and arrowheads are used. Always show overall dimensions plus critical details.
尺寸标注 指定特征的精确大小和位置。使用延伸线、尺寸线和箭头。始终显示总尺寸及关键细节。
Tolerance is the permissible variation in a dimension. A diameter of 10 ± 0.1 gives an upper limit of 10.1 mm and lower of 9.9 mm. Tolerances ensure parts fit together (interference, clearance or transition).
公差 是尺寸允许的变动量。直径 10 ± 0.1 的上限为 10.1 mm，下限为 9.9 mm。公差确保零件配合（过盈、间隙或过渡配合）。
Surface finish indicates the texture quality of a machined surface, often shown by a check mark symbol with a roughness value in micrometres (µm). Smoother surfaces require more machining time.
表面粗糙度 表示加工表面的纹理质量，常用对勾符号并标注粗糙度值（µm）。更光滑的表面需要更多加工时间。
BS symbols for welding, electronics and components are standardised. For example, a welding symbol on a drawing shows type, size and location of the weld. Familiarity with BS 8888 is expected.
英国标准 (BS) 符号 用于焊接、电子和元件的标准化。例如，图纸上的焊接符号表示焊缝类型、尺寸和位置。需要熟悉 BS 8888。
9. Systems and Control Terminology | 系统与控制术语
Input is a signal or physical quantity entering a system, e.g. a sensor detecting temperature, a switch being pressed. Inputs are converted into a form the controller can process.
输入 是进入系统的信号或物理量，例如传感器检测温度、开关被按下。输入被转换为控制器可处理的形式。
Process is the core operation that transforms input into output. In a microcontroller, it is the program logic. In a manufacturing cell, it might be assembly operations.
处理/过程 是将输入转化为输出的核心操作。在微控制器中，是程序逻辑。在制造单元中，可能是装配操作。
Output is the result delivered by the system, often an action like a motor turning, a display lighting up or a buzzer sounding. Output devices convert signals into physical movement or display.
输出 是系统交付的结果，通常是动作，如电机转动、显示器亮起或蜂鸣器发声。输出设备将信号转变为物理运动或显示。
Open-loop control has no feedback; the output does not influence the input. Example: a simple electric toaster without a thermostat — it toasts for a fixed time regardless of browning.
开环控制 没有反馈；输出不影响输入。例如：不带恒温器的简易烤面包机 — 无论焦度如何，定时烘烤。
Closed-loop control uses feedback to compare the actual output with the desired value and adjusts accordingly. A thermostat room heating system is closed-loop. Remember ‘closed loop = self-correcting’.
闭环控制 利用反馈将实际输出与期望值比较并相应调节。恒温器房间供暖系统即闭环。记住“闭环 = 自校正”。
Microcontroller is a compact integrated circuit containing a processor, memory and input/output peripherals. Programmed to execute specific tasks. Arduino uses a microcontroller.
微控制器 是包含处理器、存储器和输入输出外设的紧凑型集成电路，通过编程执行特定任务。Arduino 使用微控制器。
Actuator converts a control signal into mechanical motion. Examples: hydraulic cylinder, pneumatic piston, electric motor or solenoid. It is the ‘muscle’ of a control system.
执行器 将控制信号转换为机械运动。例如：液压缸、气动活塞、电机或电磁铁。它是控制系统的“肌肉”。
10. Fastening and Joining Methods | 紧固与连接方法
Riveting is a permanent fastening method where a rivet is placed through holes and its tail is deformed to hold parts together. Used in aircraft and bridges. The rivet swells to fill the hole.
铆接 是一种永久连接法，将铆钉穿过孔并使其尾部变形以固定零件。用于飞机制造和桥梁。铆钉膨胀填满孔。
Bolted joint uses a bolt and nut to clamp components. It is detachable, allowing maintenance. The preload tension creates a friction grip. Remember ‘bolt = removable fastener’.
螺栓连接 使用螺栓和螺母夹紧部件。可拆卸，便于维护。预紧力产生摩擦连接。记住“螺栓 = 可拆卸
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