📚 Year 10 SQA Engineering: Case Study Practical Drill | SQA 高一工程：案例分析实战演练
Mastering case studies is essential for success in SQA Engineering. This guide walks you through a structured, hands-on approach to analysing real-world scenarios, performing calculations, and presenting well-justified solutions. By the end, you will feel confident tackling any design brief or problem the exam throws at you.
掌握案例分析是SQA工程学考试成功的关键。本文将通过一套结构化的实践方法，带你逐步分析现实情景、完成计算并清晰阐述合理方案。学完之后，你将能自信应对考试中的任何设计概要或问题。
1. Understanding the Case Study Requirement | 理解案例分析要求
Case studies in SQA Engineering are designed to assess your ability to transfer textbook knowledge to practical engineering challenges. You will typically receive a brief describing a product, a system failure, or a new design need, along with specific constraints and performance targets. Your job is to interpret the problem, extract relevant data, apply correct engineering principles, and justify your recommendations.
SQA工程学中的案例分析旨在考查你将课本知识迁移到实际工程挑战的能力。题目通常会提供一个描述产品、系统故障或新设计需求的摘要，并附带具体约束条件和性能目标。你的任务是解读问题、提取相关数据、应用正确的工程原理并论证你的建议。
2. Step-by-Step Approach to Case Analysis | 案例分析分步方法
A systematic method helps you avoid missing key details. First, read the entire brief twice. Second, circle numerical values, units, and action verbs such as 'calculate', 'suggest', 'evaluate'. Third, list given parameters (forces, dimensions, materials) and what you need to find. Fourth, decide which formulas or concepts apply. Fifth, perform calculations with clear steps. Finally, write a conclusion that answers the original question and addresses any 'why' or 'justify' requests.
采用系统方法可避免遗漏关键细节。首先，通读两遍任务简介。其次，圈出数值、单位和动作词（如“计算”、“建议”、“评估”）。第三，列出已知参数（力、尺寸、材料）及待求量。第四，确定适用的公式或概念。第五，步骤清晰地完成计算。最后，写出回应原问题、并对任何“为什么”或“论证”要求作出回应的结论。
3. Reading and Deconstructing the Brief | 阅读与拆解任务简介
Look for hidden clues: a phrase like 'must be lightweight' suggests a need to compare material densities or specific strengths. 'Minimise cost' implies a trade-off analysis. 'Operates in wet conditions' points to corrosion resistance requirements. Highlight constraints such as budget limits, geometric restrictions, maximum allowed mass, or safety standards that must be satisfied.
寻找隐藏线索：“必须轻便”暗示需比较材料密度或比强度；“成本最小化”意味着需要权衡折衷；“在潮湿环境中工作”指向耐腐蚀要求。突出约束条件，例如预算上限、几何限制、最大允许质量或必须满足的安全标准。
4. Identifying Key Engineering Concepts | 识别关键工程概念
Every case study maps onto specific National 5 topics. For a lifting mechanism, consider moments, equilibrium, and pulley systems. For a structural support, forces, stress, strain, and factor of safety are central. For an electronic control unit, you may need Ohm's Law and power calculations. Quickly mind-map which curriculum areas are being tested before you begin writing.
每个案例分析都对应着特定的National 5课程主题。对于提升机构，要想到力矩、平衡和滑轮系统。对于结构支撑，力、应力、应变和安全系数是核心。对于电子控制单元，则可能需要欧姆定律和功率计算。在动笔前快速将考查的课程知识领域列成思维导图。
5. Data Collection and Interpretation | 数据收集与解读
Extract all numerical values and convert them to SI units (metres, kilograms, seconds, newtons). If a graph is provided, such as a force-extension curve, read off key points carefully. Create a small table to organise data: material properties (yield strength, Young's modulus, density), geometric dimensions, and applied loads.
提取所有数值并转换为国际单位（米、千克、秒、牛顿）。若提供图表，如力-伸长量曲线，仔细读取关键点。自制一个小表格来整理数据：材料属性（屈服强度、杨氏模量、密度）、几何尺寸和外加载荷。
Example data for three candidate materials:
三种备选材料的示例数据：
| Material | Yield Strength (MPa) | Density (kg/m³) |
|---|---|---|
| Steel | 250 | 7850 |
| Aluminium alloy | 275 | 2700 |
| Treated timber | 35 | 600 |
With this table, you can quickly compare specific strength (yield strength ÷ density) to identify lightweight options.
借助此表，你可以快速比较比强度（屈服强度÷密度），以找出轻量化选项。
6. Applying Calculations and Formulas | 应用计算与公式
Always show your working step by step. Write down the formula, substitute the numbers, and state the final answer with correct units. Common formulas include:
始终分步展示演算。写下公式、代入数字，并写出带正确单位的最终答案。常用公式包括：
σ = F / A
ε = ΔL / L₀
F = m × a
Moment = Force × perpendicular distance
red, use allowable stress = yield strength / factor of safety. State any assumptions (e.g. 'loading is static', 'beam is simply supported', 'uniform cross-section').
若需要安全系数，使用许用应力=屈服强度/安全系数。说明所有假设（如“载荷是静态的”、“梁为简支”、“截面均匀”）。
7. Evaluating Materials and Processes | 评估材料与工艺
Compare materials using a decision matrix. Score each candidate against criteria: strength, weight, cost, durability, and environmental impact. Weight the criteria according to the brief's priorities. Similarly, evaluate manufacturing processes: casting achieves complex shapes but may have high initial tooling cost; machining offers precision but wastes material; 3D printing is good for prototypes and low volumes.
使用决策矩阵比较材料。根据强度、重量、成本、耐久性和环境影响对每个候选材料打分。根据任务概要的优先级对各个准则加权。同样地，评估制造工艺：铸造可实现复杂形状，但初始模具成本可能很高；机加工精度高，但浪费材料；3D打印适合原型和小批量生产。
8. Design Considerations and Constraints | 设计考量与约束
Identify all constraints explicitly: maximum mass, overall dimensions, load requirements, budget, and any legal standards (e.g. building regulations, CE marking). A footbridge design might need a clear span of 20 m, must not obstruct water flow, and must support a live load of 5 kN/m². Your solution must demonstrably meet every constraint, not just the obvious ones.
明确识别所有约束条件：最大质量、整体尺寸、载荷要求、预算及任何法律标准（如建筑规范、CE标志）。人行桥设计可能需要净跨度20 m，不得阻碍水流，且必须支持5 kN/m²活荷载。你的方案必须可证明地满足每一个约束，而不仅仅是显而易见的那些。
9. Environmental and Ethical Factors | 环境与道德因素
Sustainability is increasingly important in engineering. Discuss material sourcing (recycled content, FSC-certified timber), energy consumption during production, and end-of-life recyclability. Ethical considerations include ensuring workplace safety during manufacture, accessibility of the final product for all users, and avoiding conflict minerals. Even a brief mention of these factors can raise your answer to a higher mark band.
可持续性在工程中日益重要。讨论材料采购（再生成分、FSC认证木材）、生产过程中的能耗以及产品报废后的可回收性。道德考量包括确保制造过程中的工作场所安全、最终产品对所有使用者的无障碍性以及避免使用冲突矿产。哪怕简短提及这些因素，都能让你的答案提升一个档次。
10. Presenting Your Solution Clearly | 清晰呈现你的解决方案
A well-structured answer is easy to mark and demonstrates logical thinking. Use headings or numbered steps. Where appropriate, include simple labelled sketches (even hand-drawn in exams) and bulleted lists. Show formulas, substituted values, and final answers clearly. End with a conclusion that directly answers the question and justifies your choice using evidence from your calculations and evaluations.
结构良好的答案既便于评分，又展现出逻辑思维。使用标题或编号步骤。适当添加简易标注草图（考试中手绘也可）和项目符号列表。清晰展示公式、代入值和最终答案。最后用结论直接回答问题，并用计算和评估中的证据论证你的选择。
11. Practice Case: Bridge Design Challenge | 实战案例：桥梁设计挑战
Let's apply everything to a realistic scenario. Task: design a light pedestrian bridge spanning 20 m across a stream. The bridge deck is 2 m wide. It must support a maximum uniformly distributed load of 4 kN/m², withstand weather exposure, and cost less than £15,000. Available materials: steel (σy = 250 MPa), aluminium alloy (σy = 275 MPa), and treated timber (σy = 35 MPa). You may assume the beam is simply supported.
让我们将所有知识应用到一个真实情景。任务：设计一座跨越溪流的轻量化人行桥，跨度20 m，桥面宽2 m。桥梁须承受最大均布荷载4 kN/m²，耐候，且成本低于15,000英镑。可选材料：钢（σy = 250 MPa）、铝合金（σy = 275 MPa）、防腐木材（σy = 35 MPa）。可假设梁为简支。
equally, each carries w = 4 kN/m. For a simply supported beam, maximum bending moment is:
首先计算作用在一根主梁上的线荷载。桥面总荷载=4 kN/m² × 2 m宽=8 kN每米长度。若两根梁平均分担，每根梁承担w=4 kN/m。对于简支梁，最大弯矩为：
Mmax = wL² / 8
Mmax = (4 kN/m) × (20 m)² / 8 = 200 kN·m
Allowable stress for steel: 250 MPa / 1.5 = 166.7 MPa. Required section modulus S = M / σallow 1 UB section has S ≈ 1100 cm³ (close); we could upsize to 406×178×60 UB with S ≈ 1400 cm³.
考虑安全系数1.5。钢许用应力：250 MPa / 1.5 = 166.7 MPa。所需截面模量S = M / σallow = 200×10³ N·m / 166.7×10⁶ Pa = 1.20×10⁻³ m³ = 1200 cm³。标准356×171×51 UB型钢截面的S约为1100 cm³（接近）；可升级至406×178×60 UB，S约为1400 cm³。
For aluminium: σallow inium is much lighter (density 2700 kg/m³ vs. 7850 kg/m³) but often more expensive per kg and may have larger deflections, which must also be checked.
铝合金：σallow = 275/1.5 = 183.3 MPa。S=200×10³ / 183.3×10⁶ =
Published by TutorHao | Year 10 工程 Revision Series | aleveler.com
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