📚 IGCSE Cambridge Engineering: Core Knowledge Checklist | IGCSE Cambridge 工程：核心知识点梳理
This checklist summarises the core knowledge areas for Cambridge IGCSE Engineering. It is designed to help students revise key definitions, formulas and practical applications before assessment. Use it alongside past papers, practical project work and teacher feedback.
本清单总结了剑桥 IGCSE 工程学科的核心知识领域，旨在帮助学生在考前复习关键定义、公式和实际应用。建议结合历年真题、课程项目和教师反馈一起使用。
1. Engineering Design Process | 工程设计流程
The design process moves from a brief through research, specification, idea generation, modelling, testing and evaluation. Engineers do not jump straight to a final solution; they use iterative cycles to reduce risk and improve performance.
设计流程从设计任务书开始，经过调研、规格说明、方案构思、建模、测试和评估。工程师不会直接跳到最终方案，而是通过迭代循环降低风险并提升性能。
Key terms include design brief, design specification, prototype, constraint, and evaluation. A good specification is measurable, such as ‘must support a 5 kg load without permanent deformation’.
关键术语包括设计任务书、设计规格、原型、约束条件和评估。好的规格说明是可测量的，例如”必须在不发生永久变形的情况下支撑 5 kg 载荷”。
A typical sequence is: identify the problem, write a brief, research, write a specification, generate ideas, choose a solution, build a prototype, test, evaluate, and modify.
典型顺序是：识别问题、撰写任务书、调研、撰写规格说明、构思方案、选择方案、制作原型、测试、评估并修改。
2. Materials and Properties | 材料与性能
Common engineering materials include mild steel, aluminium alloy, copper, brass, ABS, acrylic, nylon, wood and composites. Selection depends on mechanical, thermal, electrical and environmental properties.
常见工程材料包括低碳钢、铝合金、铜、黄铜、ABS、亚克力、尼龙、木材和复合材料。材料选择取决于力学、热学、电气和环境性能。
Important mechanical properties include hardness, toughness, ductility, malleability, elasticity, plasticity, brittleness and fatigue resistance. Thermal and electrical conductivity, density and corrosion resistance also affect material choice.
重要的力学性能包括硬度、韧性、延展性、可锻性、弹性、塑性、脆性和疲劳抗力。导热性、导电性、密度和耐腐蚀性也会影响材料选择。
| Material | 材料 | Typical property combination | 典型性能组合 | Common use | 常见用途 |
|---|---|---|
| Mild steel | 低碳钢 | Tough, ductile, magnetic, corrodes | 坚韧、有延展性、有磁性、易生锈 | Frames, fasteners | 框架、紧固件 |
| Aluminium alloy | 铝合金 | Light, corrosion-resistant, ductile | 轻、耐腐蚀、有延展性 | Aircraft skins, enclosures | 飞机蒙皮、外壳 |
| Copper | 铜 | Excellent conductor, ductile | 优良导体、有延展性 | Wires, pipes | 导线、管道 |
| ABS | ABS 塑料 | Impact-resistant, thermoformable | 抗冲击、可热塑成型 | Casings, prototypes | 外壳、原型 |
| Acrylic | 亚克力 | Clear, stiff, brittle | 透明、坚硬、较脆 | Windows, display covers | 视窗、展示盖板 |
| Nylon | 尼龙 | Low friction, wear-resistant | 低摩擦、耐磨 | Gears, bearings | 齿轮、轴承 |
3. Forces, Stress and Strain | 力、应力与应变
Force is a vector measured in newtons (N). When a force acts on a material, it creates internal stress. Stress is force per unit area and is measured in pascals (Pa) or N/m².
力是矢量，单位为牛顿（N）。当力作用在材料上时，会产生内部应力。应力是单位面积上的力，单位为帕斯卡（Pa）或 N/m²。
stress = F / A
Tensile stress stretches a material, compressive stress squeezes it, and shear stress acts parallel to a face. Strain is the ratio of extension to original length, so it has no units.
拉伸应力使材料伸长，压缩应力使材料缩短，剪切应力平行于作用面。应变是伸长量与原长的比值，因此没有单位。
strain = ΔL / L₀
Young’s modulus measures stiffness and is calculated as stress divided by strain within the elastic limit. A stiffer material has a higher Young’s modulus.
杨氏模量衡量材料刚度，在弹性限度内等于应力除以应变。刚度越大的材料，杨氏模量越高。
E = stress / strain
4. Mechanisms and Mechanical Systems | 机构与机械系统
Mechanisms change the size, direction or type of motion. Levers, linkages, gears, pulleys and cams are basic building blocks. A lever rotates around a fulcrum; class 1, class 2 and class 3 levers differ in the relative positions of effort, load and fulcrum.
机构可以改变运动的大小、方向或类型。杠杆、连杆、齿轮、带轮和凸轮是基本构件。杠杆绕支点旋转；一类、二类和三类杠杆的区别在于动力、负载和支点的相对位置。
Mechanical advantage (MA) is the ratio of load to effort. Velocity ratio (VR) is the ratio of distance moved by effort to distance moved by load. Efficiency compares useful work output with work input.
机械利益（MA）是负载与动力的比值。速度比（VR）是动力移动距离与负载移动距离的比值。效率将有效输出功与输入功进行比较。
MA = load / effort
VR = distance moved by effort / distance moved by load
efficiency = (useful work output / work input) × 100%
For gears, the speed ratio is the inverse of the tooth ratio. A small driver gear turning a larger driven gear increases torque but reduces speed.
对于齿轮，转速比与齿数比成反比。小主动齿轮带动大从动齿轮会增大扭矩但降低转速。
5. Electronics and Control | 电子与控制
Basic circuits include a power supply, conductors, protection, input sensors, a control element and output devices. Ohm’s law links voltage, current and resistance, and is essential for circuit calculations.
基本电路包括电源、导线、保护装置、输入传感器、控制元件和输出装置。欧姆定律将电压、电流和电阻联系起来，是电路计算的基础。
V = I × R
P = V × I
Common input devices include thermistors, light-dependent resistors (LDRs), switches and potentiometers. Output devices include LEDs, buzzers, motors and relays. A transistor or MOSFET can act as an electronic switch, and a 555 timer can generate pulses.
常见输入设备包括热敏电阻、光敏电阻（LDR）、开关和电位器。输出设备包括 LED、蜂鸣器、电机和继电器。晶体管或 MOSFET 可作为电子开关，555 定时器可产生脉冲。
A potential divider uses two resistors to produce a controlled output voltage. It is widely used with sensors to trigger switching circuits.
分压电路使用两个电阻产生可控的输出电压。它广泛用于配合传感器触发开关电路。
V_out = V_in × R₂ / (R₁ + R₂)
6. Energy, Power and Efficiency | 能量、功率与效率
Energy is the capacity to do work, measured in joules (J). Mechanical work is force multiplied by distance moved in the direction of the force. Power is the rate of doing work and is measured in watts (W).
能量是做功的能力，单位为焦耳（J）。机械功等于力乘以沿力方向移动的距离。功率是做功的速率，单位为瓦特（W）。
W = F × d
P = W / t
In mechanical and electrical systems, no conversion is 100% efficient; losses appear as heat, noise or friction. Sankey diagrams show energy transfers and wasted energy clearly by using arrow widths proportional to energy flow.
在机械和电气系统中，任何转换效率都不是 100%；损失表现为热量、噪声或摩擦。桑基图通过宽度与能量流量成正比的箭头清晰地显示能量传递和浪费的能量。
efficiency = (useful output energy / total input energy) × 100%
7. Manufacturing Processes | 制造工艺
Manufacturing processes are grouped into forming, casting, machining, joining and additive manufacturing. Choosing a process depends on material, batch size, tolerance and cost.
制造工艺可分为成型、铸造、切削加工、连接和增材制造。工艺选择取决于材料、批量大小、公差和成本。
Machining processes such as drilling, turning and milling remove material to create accurate parts. Joining includes mechanical fasteners, adhesives, soldering and welding. Modern 3D printing builds parts layer by layer for prototypes and small batches.
钻孔、车削和铣削等切削加工通过去除材料来制造精确零件。连接方法包括机械紧固件、胶粘剂、锡焊和焊接。现代 3D 打印通过逐层堆积来制造零件，适用于原型和小批量生产。
Quality control checks dimensions, surface finish and strength. Tolerance is the acceptable variation from a nominal size; a tighter tolerance usually increases manufacturing cost.
质量控制要检查尺寸、表面光洁度和强度。公差是相对公称尺寸允许的变动量；公差越严格，制造成本通常越高。
8. Structures and Loads | 结构与载荷
Structures must resist static and dynamic loads without excessive deflection or failure. Common loads include dead loads, live loads and wind loads. Compression members may buckle, while tension members may fracture if overloaded.
结构必须承受静载荷和动载荷，不发生过大变形或破坏。常见载荷包括恒载、活载和风载。受压构件可能屈曲，受拉构件过载时可能断裂。
Moments measure the turning effect of a force. For equilibrium, the sum of clockwise moments about a pivot equals the sum of anticlockwise moments.
力矩衡量力的转动效应。平衡时，绕支点的顺时针力矩之和等于逆时针力矩之和。
moment = force × perpendicular distance from pivot
sum of clockwise moments = sum of anticlockwise moments
Triangular frames are often used in structural systems because they are rigid and distribute loads efficiently through tension and compression in members.
三角形框架常用于结构系统，因为它们具有刚性，并能通过构件中的张力和压力高效地分配载荷。
9. Health, Safety and Risk Assessment | 健康、安全与风险评估
Workshop safety starts with risk assessment: identify hazards, evaluate the risk, and apply control measures. Personal protective equipment (PPE) includes safety glasses, ear defenders, gloves and protective footwear.
车间安全始于风险评估：识别危险、评估风险并采取控制措施。个人防护装备（PPE）包括护目镜、耳罩、手套和防护鞋。
Safe practice includes isolating machines before maintenance, using guards, keeping work areas clean, and following COSHH rules for hazardous substances. Electrical safety means checking insulation, earthing and fuses.
安全操作规程包括在检修前隔离机器、使用防护罩、保持工作区域整洁，以及遵守有害物质控制（COSHH）规定。电气安全包括检查绝缘、接地和保险丝。
A risk assessment should be documented and reviewed. Control measures follow a hierarchy: eliminate the hazard, substitute, use engineering controls, apply administrative controls, and provide PPE as the last line of defence.
风险评估应记录并复审。控制措施遵循层级顺序：消除危险、替代、使用工程控制、实施管理控制，最后才提供个人防护装备作为最后一道防线。
10. Communication and Drawing | 工程图学与沟通
Engineers communicate designs through orthographic drawings, isometric sketches, parts lists and annotations. Correct dimensioning follows standards, with all dimensions measured in millimetres unless stated otherwise.
工程师通过正投影图、等轴测草图、零件清单和注释来交流设计。正确的尺寸标注遵循标准，除另有说明外，所有尺寸均以毫米为单位。
Orthographic projection shows the object from front, side and plan views. Isometric drawing provides a 3D-like view at 30° angles, making it easier for non-specialists to visualise the design.
正投影图从主视图、侧视图和俯视图展示物体。等轴测图以 30° 角提供类似三维的视图，使非专业人士更容易理解设计。
CAD models allow rapid modification and simulation. When presenting a proposal, engineers justify choices against the specification and evaluation criteria, using clear language and diagrams.
CAD 模型便于快速修改和模拟。在展示方案时，工程师需根据规格说明和评价标准证明其选择合理，并使用清晰的语言和图示。
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