📚 Case Study Challenge: Engineering in Action | 案例分析实战演练：工程在行动
Engineering is all about solving problems creatively using science and mathematics. In Year 7 Cambridge Engineering, you do not just learn theories—you dive into real-world challenges through case studies. This article presents two exciting hands-on projects: the Paper Bridge Challenge and the Balloon-Powered Car. You will follow the engineering design process step by step, test your ideas, and think like a real engineer. Let us get started on this practical revision journey.
工程学就是运用科学和数学创造性地解决问题。在剑桥七年级工程课程中，你不仅仅学习理论——还通过案例研究深入现实挑战。本文介绍两个激动人心的动手项目：纸桥挑战和气球动力小车。你将逐步遵循工程设计流程，测试你的想法，并像真正的工程师一样思考。让我们踏上这段实践复习之旅吧。
1. What Is an Engineering Case Study? | 什么是工程案例分析？
An engineering case study is a detailed look at a specific problem and how it was solved. It helps you understand the decisions engineers make, from identifying a need to testing a final product. In our classroom, case studies are smaller-scale projects where you design, build, and test a solution yourself. By working through them, you learn to apply concepts like forces, structures, and energy in a practical way.
工程案例分析是对一个具体问题及其解决方法的详细审视。它能帮助你理解工程师所做的决策，从识别需求到测试最终产品。在我们的课堂上，案例分析是缩小版的项目，你将在其中亲自设计、建造并测试解决方案。通过完成这些项目，你将学会如何实际应用力、结构和能量等概念。
2. The Engineering Design Process | 工程设计流程
Every case study follows a logical design process. First, you define the problem clearly. Second, you brainstorm possible solutions and sketch your ideas. Third, you select the best design and plan the build. Fourth, you create a prototype. Fifth, you test it fairly, collect data, and evaluate how well it meets the criteria. Finally, you improve your design based on what you learned. This cycle—Ask, Imagine, Plan, Create, Test, Improve—is the heart of engineering.
每个案例研究都遵循逻辑性的设计流程。首先，明确界定问题。第二，头脑风暴可能的解决方案并勾画你的构思。第三，选出最佳设计并规划建造。第四，制作原型。第五，公平测试，收集数据，并评估它在多大程度上满足标准。最后，根据所学改进你的设计。这个周期——提问、想象、规划、创造、测试、改进——是工程学的核心。
3. Case Study 1: The Paper Bridge Challenge | 案例一：纸桥挑战
Your mission is to design a bridge using only A4 paper and masking tape that can span a 30 cm gap and hold the most weight before collapsing. The bridge must be free-standing—no supports in the middle. You will work as a team, explore different bridge shapes, and apply your knowledge of forces and structures.
你的任务是仅使用 A4 纸和遮蔽胶带来设计一座桥，桥要跨越 30 厘米的间隙，并在坍塌前承受尽可能大的重量。桥必须是自支撑的，中间无支柱。你将团队合作，探索不同的桥型，并运用力和结构的知识。
Before building, we must understand the problem constraints. The span is fixed at 30 cm, the materials are limited to 10 sheets of paper and 1 m of tape, and success is measured by the maximum load held. The load can be applied using small weights added gradually at the centre.
在建造之前，我们必须了解问题约束条件。跨度固定为 30 厘米，材料限于 10 张纸和 1 米胶带，成功与否通过能承受的最大载荷来衡量。载荷可以通过在中心逐渐增加小砝码来施加。
4. Analysing the Problem: Forces on a Bridge | 分析问题：桥上的力
A bridge experiences two main types of forces: compression (pushing together) and tension (pulling apart). When a weight sits on a bridge, the top part of the deck can compress while the bottom part stretches. In a truss bridge, triangles help distribute these forces evenly. Understanding this helps you decide how to fold, roll, or layer the paper to make it stronger in compression and tension.
桥主要承受两种力：压力（向一起推）和拉力（向外拉）。当重物放在桥上，桥面板的上部可能受压，而下部受拉。在桁架桥中，三角形有助于均匀分布这些力。理解这一点能帮助你决定如何折叠、卷曲或堆叠纸张，使其在抗压和抗拉方面更强。
We can also think about the dead load (the bridge’s own weight) and the live load (the weights added). A good design is lightweight but stiff. Too much material makes the bridge heavy and weak under its own weight.
我们还可以考虑恒荷载（桥自身的重量）和活荷载（添加的重物）。好的设计是轻质而坚固的。材料过多会使桥变重，在自身重量下变弱。
5. Brainstorming & Sketching Solutions | 头脑风暴与草图设计
Grab a pencil and paper. Sketch at least three different bridge forms: a beam bridge (flat deck), an arch bridge, and a truss bridge with folded beams. Label the parts where you expect tension and compression. Annotate your sketches with notes on how you will roll paper tubes for beams or create triangular side supports. No idea is silly at this stage; the goal is to generate many possibilities before evaluating.
拿起铅笔和纸。勾画至少三种不同的桥型：梁桥（平桥面）、拱桥和带有折叠梁的桁架桥。标出你预期受拉和受压的部位。在草图上注释你将如何卷纸管做梁，或制作三角形侧支撑。在此阶段任何想法都不荒唐；目标是在评估前生成多种可能性。
Consider forces: an arch shape works well in compression, so tightly rolled paper tubes could form a curved arch. A truss uses interconnected triangles; you could build zigzag patterns from folded strips. A beam bridge is simplest but may sag; you can reinforce it with corrugated layers (like cardboard).
考虑作用力：拱形在受压下表现良好，因此紧紧卷起的纸管可以形成弯曲的拱。桁架使用相互连接的三角形；你可以用折叠纸条建造锯齿形图案。梁桥最简单，但可能下陷；你可以用瓦楞层（像纸板那样）进行加固。
6. Building a Prototype: Materials & Techniques | 构建原型：材料与工艺
With your design selected, start building. Cut paper into strips and roll them tightly around a pencil to form strong columns; secure with tiny pieces of tape. For beams, fold paper lengthwise into V-shapes or U-shapes to increase stiffness without adding weight. Triangles can be made by folding a strip into a continuous zigzag and taping the ends. Work carefully—neat construction leads to a stronger bridge.
选定设计后，开始建造。将纸裁成条，紧紧绕铅笔卷起形成坚固的柱子；用少量胶带固定。做梁时，将纸沿纵向折叠成 V 形或 U 形，以增加刚度而不增加重量。三角形可以通过将纸条折成连续的锯齿形并用胶带固定两端来制作。精心施工——整洁的构造会带来更坚固的桥。
You must manage your resources. Use only the allowed 10 sheets of paper and 1 m of tape. Plan how to cut each sheet efficiently. Waste not, want not. If you roll a tube, one sheet can give you a strong member roughly 30 cm long. You might also laminate strips by folding and taping layers together—test a small sample first.
你必须管理好资源。只能使用允许的 10 张纸和 1 米胶带。规划如何高效裁剪每张纸。俭以防匮。如果你卷一个纸管，一张纸可以给你一个长约 30 厘米的坚固杆件。你也可以通过折叠和胶合叠层来制作层压条——可以先测试一个小样。
7. Testing and Measuring Performance | 测试与测量性能
Place your bridge across two desks exactly 30 cm apart. Prepare a hook or basket to hang from the centre of the bridge. Slowly add small masses (e.g., 50 g weights) one by one until collapse. Record the total mass held just before failure. Also observe the type of failure: did it buckle in the middle? Did a joint break? Note these down for your evaluation.
将桥跨放在相距恰好 30 厘米的两张课桌之间。准备一个钩子或小篮悬挂在桥中央。缓缓逐个增加小质量（如 50 g 砝码），直至垮塌。记录刚好在破坏前支撑的总质量。同时观察破坏类型：是在中间弯折了？还是节点脱落了？记录下来用于评估。
For accurate results, repeat the test at least twice. Calculate the average maximum load. Use a table to compare your bridge’s performance with others in the class. Here is an example recording format:
为求准确，测试至少重复两次。计算平均最大载荷。用表格比较你的桥与班上其他同学的表现。下面是一个记录格式示例：
| Bridge Design | Mass Held (g) Trial 1 | Mass Held (g) Trial 2 | Average Mass (g) |
|---|---|---|---|
| Flat beam | 350 | 300 | 325 |
| Truss with rolled tubes | 850 | 910 | 880 |
| Paper arch | 720 | 695 | 707.5 |
Use this data to identify which design strategies worked best. For your revision, think about which shapes resist bending and why.
使用这些数据找出哪种设计策略最优。在复习时，思考哪种形状能抵抗弯曲以及为什么。
8. Evaluating Results and Making Improvements | 评估结果与改进
Now answer these reflection questions. Did your bridge meet the 30 cm span requirement? How did the failure happen—sudden snap or gradual sagging? What part was the weakest? Could you redistribute mass or add reinforcement there? Compare your design to a real bridge: did you use an arch, truss, or suspension principle? Engineers do the same after every prototype test.
现在回答这些反思问题。你的桥满足 30 厘米跨度的要求了吗？破坏是如何发生的——突然折断还是逐渐下陷？最薄弱的部分是哪里？你能重新分配质量或在那里加固吗？将你的设计与真实的桥进行比较：你是否使用了拱形、桁架或悬索原理？工程师在每次样机测试后也会做同样的事。
Based on your evaluation, propose one specific improvement. For instance, “I will double-layer the bottom beam to resist tension,” or “I will add cross-bracing between vertical supports to prevent twisting.” Then, if time allows, rebuild and retest. This iterative loop is the hallmark of good engineering.
基于评估，提出一项具体的改进。例如，“我将底部梁做成双层以抵抗拉力”或“我将在竖向支撑间增加交叉撑以防止扭转”。然后，如果时间允许，重新建造并再次测试。这种迭代循环是优秀工程的标志。
9. Case Study 2: Balloon-Powered Car | 案例二：气球动力小车
The second case challenges you to build a vehicle that moves forward using only the air escaping from a balloon. Materials are a cardboard base, straws, bottle caps for wheels, wooden skewers for axles, tape, and one balloon. The car must travel at least 2 m in a straight line. This project teaches you about Newton’s third law, friction, and energy transfer.
第二个案例挑战你建造一辆仅靠气球释放的空气来前进的小车。材料包括纸板底座、吸管、瓶盖作车轮、竹签作车轴、胶带和一个气球。小车必须直线行驶至少 2 米。这个项目教你牛顿第三定律、摩擦和能量转移。
The problem statement: design a lightweight, low-friction vehicle that converts the potential energy of stretched balloon rubber into kinetic energy of motion. The constraints: only given materials, and you cannot push the car—only release the balloon air.
问题陈述：设计一辆轻质、低摩擦的小车，将拉伸的气球橡胶的势能转换为运动的动能。约束条件：仅限给定材料，且不能推动小车——只能释放气球中的空气。
10. Exploring Forces: Thrust and Friction | 探索力：推力与摩擦
When you let go of the inflated balloon, air rushes out backward, and an equal and opposite force pushes the car forward. This is thrust. Mathematically, if the air exits with mass flow rate and speed, the thrust F can be simplified as the reaction force. For a smooth ride, you must minimise friction between axles and straw bearings, and between wheels and the floor. Use the equation: Fnet = thrust – friction to understand how the car accelerates.
当你松开充气的气球，空气向后冲出，一个等大反向的力推动小车前进。这就是推力。数学上，如果空气以一定质量和速度流出，推力 F 可简化为反作用力。为了平稳行驶，你必须尽量减少车轴与吸管轴承之间以及车轮与地面之间的摩擦力。使用方程：净力 = 推力 – 摩擦力 来理解小车如何加速。
a = (Fthrust – Ffriction) ÷ m
The lighter the car (smaller m), the greater the acceleration for the same net force. So you need a stiff but light chassis. Cardboard can be cut with holes to reduce weight.
小车越轻（m 越小），同样净力下加速度越大。因此你需要坚固而轻质的底盘。纸板可以切孔来减轻重量。
11. Building and Testing the Balloon Car | 建造与测试气球动力小车
Construct the car: tape two straws parallel on the underneath of the cardboard as axle holders. Insert wooden skewers through the straws; attach bottle caps as wheels—ensure wheels spin freely. Inflate the balloon and tape its mouthpiece to a straw, then fix the straw on top of the car pointing backwards. Design a valve or simply pinch the balloon until test time.
建造小车：在纸板底面平行粘贴两根吸管作为轴套。将竹签穿过吸管；安装瓶盖作为车轮——确保车轮能自由转动。吹起气球，将其嘴部用胶带固定在吸管上，然后把吸管朝后固定在车顶。设计一个阀门，或者测试前捏住气球即可。
Test on a smooth surface. Mark a start line. Release the balloon and measure the distance travelled with a tape measure. Record time with a stopwatch to calculate average speed using:
在光滑表面上测试。标记起始线。松开气球，用卷尺测量行驶距离。用秒表记录时间，计算平均速度：
average speed = total distance ÷ total time
Run three trials and compute averages. If the car veers off course, check wheel alignment; adjust axles. If it barely moves, reduce friction or lighten the chassis. Graph your distance vs. time to visualise motion.
进行三次试验并计算平均值。如果小车偏离路线，检查车轮对准情况；调整车轴。如果几乎不动，减少摩擦或减轻底盘。绘制距离-时间图来可视化运动。
12. Real-World Engineering Connections | 现实世界工程连接
The Paper Bridge relates to civil engineering. Bridges like the Golden Gate use trusses and suspension cables to manage tension and compression. The balloon car mirrors rocket propulsion and automotive engineering. Jet engines and rockets expel gas backward to move forward—exactly like your balloon. Engineers use prototypes and iteration to refine everything from smartphones to spacecraft. Your case studies are miniature versions of these processes.
纸桥挑战与土木工程相关。像金门大桥这样的桥梁利用桁架和悬索来管理拉力和压力。气球小车则映射了火箭推进和汽车工程。喷气发动机和火箭向后喷射气体来前进——正如你的气球。工程师使用原型和迭代来完善从智能手机到航天器的一切。你的案例分析便是这些过程的缩影。
By understanding how triangles create rigidity or how reducing friction improves efficiency, you are building foundational knowledge for future IGCSE and A Level Design & Technology or Physics. Keep an engineering notebook; record your observations, sketches, and data—the habit of a true engineer.
通过理解三角形如何形成刚性，或减少摩擦如何提高效率，你正在为未来的 IGCSE 和 A Level 设计与技术或物理学科奠定基础。准备一本工程笔记本；记录观察、草图和资料——这是真正工程师的习惯。
Published by TutorHao | Engineering Revision Series | aleveler.com
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