IGCSE CAIE Engineering: Core Knowledge Overview | IGCSE CAIE 工程：核心知识点梳理

📚 IGCSE CAIE Engineering: Core Knowledge Overview | IGCSE CAIE 工程：核心知识点梳理

This article provides a concise overview of the core knowledge areas covered in the Cambridge IGCSE Engineering syllabus (0420). Understanding these fundamental topics is essential for success in both the written examination and the practical project. From material properties to manufacturing processes, and from mechanical systems to health and safety, each section outlines key concepts and terms.

本文简要梳理了剑桥 IGCSE 工程（0420）教学大纲中的核心知识领域。充分理解这些基础主题对于在书面考试和实践项目中取得成功至关重要。从材料性能到制造工艺，从机械系统到健康与安全，每个章节都将概括关键概念和术语。

1. Engineering Materials and Properties | 工程材料与性能

Engineers must select appropriate materials based on their mechanical and physical properties. Common material classifications include ferrous metals (e.g., mild steel, cast iron), non-ferrous metals (e.g., aluminium, copper), polymers (thermoplastics and thermosets), ceramics, and composites.

工程师必须依据材料的力学与物理性能选材。常见材料分类包括黑色金属（如低碳钢、铸铁）、有色金属（如铝、铜）、聚合物（热塑性与热固性）、陶瓷以及复合材料。

Key mechanical properties include tensile strength, compressive strength, hardness, toughness, ductility, and elasticity. For example, mild steel has high tensile strength and ductility, making it ideal for structural applications, while cast iron offers high compressive strength but is brittle.

关键力学性能包括抗拉强度、抗压强度、硬度、韧性、延展性和弹性。例如，低碳钢具有高抗拉强度和延展性，适合结构应用；而铸铁抗压强度高，但脆性大。

Physical properties such as density, thermal conductivity, and electrical conductivity are also crucial. The selection process often involves trade-offs; for instance, aluminium is chosen over steel in aircraft because its low density offsets its lower strength.

密度、导热性和导电性等物理性能同样至关重要。选材过程往往需要权衡取舍；例如，航空领域选用铝而非钢，是因为其低密度的优势可以弥补强度上的不足。

2. Mechanical Systems | 机械系统

Mechanical systems involve mechanisms that transmit and transform motion and force. Levers, linkages, gears (spur, bevel, worm), pulleys, and cams are fundamental components.

机械系统涉及传递与转换运动和力的机构。杠杆、连杆、齿轮（直齿、锥齿、蜗轮）、滑轮和凸轮是基本部件。

The mechanical advantage (MA) of a lever system is calculated as load ÷ effort. Velocity ratio (VR) compares the distance moved by effort to the distance moved by load. Efficiency = (MA ÷ VR) × 100%.

杠杆系统的机械效益（MA）的计算公式为负载 ÷ 驱动力。速度比（VR）是驱动力移动距离与负载移动距离之比。效率 = （MA ÷ VR）× 100%。

Mechanical Advantage (MA) = Load ÷ Effort

Efficiency (%) = (MA ÷ VR) × 100

Gears transmit rotary motion and can change speed and torque. The gear ratio is determined by the number of teeth: Gear ratio = Number of teeth on driven gear ÷ Number of teeth on driver gear. Increasing torque reduces speed and vice versa.

齿轮传递旋转运动，并可改变转速和转矩。齿轮比由齿数决定：齿轮比 = 从动轮齿数 ÷ 主动轮齿数。增大转矩会降低转速，反之亦然。

Linkages, such as the four-bar linkage, convert motion types. A crank and slider mechanism transforms rotary motion into linear reciprocating motion, commonly found in internal combustion engines.

四杆机构等连杆机构可转换运动类型。曲柄滑块机构将旋转运动转化为直线往复运动，常见于内燃机。

3. Structures | 结构

Structures must withstand forces without failing or deforming excessively. The main types of forces include tension (pulling), compression (pushing), bending, torsion (twisting), and shear.

结构必须能够承受力而不发生破坏或过度变形。主要受力类型包括拉伸、压缩、弯曲、扭转和剪切。

Stress (σ) is force per unit area: σ = F ÷ A. Strain (ε) is the extension per unit length: ε = ΔL ÷ L₀. The Young’s modulus (E) is the ratio of stress to strain in the elastic region: E = σ ÷ ε.

应力（σ）是单位面积上的力：σ = F ÷ A。应变（ε）是单位长度的伸长量：ε = ΔL ÷ L₀。杨氏模量（E）是弹性范围内应力与应变的比值：E = σ ÷ ε。

σ = F ÷ A

ε = ΔL ÷ L₀

E = σ ÷ ε

Trusses use triangular arrangements to distribute loads efficiently, with members under either pure tension or compression. Beams experience bending moments and shear forces; engineers analyze these to determine the required cross-section.

桁架利用三角形布置有效分配载荷，各构件只承受纯拉伸或纯压缩。梁承受弯矩和剪力；工程师通过分析这些力来确定所需的截面尺寸。

Buckling can occur in slender compression members. The factor of safety is applied to ensure structures can withstand loads beyond the expected maximum.

Published by TutorHao | IGCSE 工程 Revision Series | aleveler.com

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