结论：试验参数是场景的抽象，不是随便定的数字
跌落试验会规定一个下落高度和一种下落姿态。很多人把这两个参数当成需要满足的门槛数字，测过了就算完事。
更有用的理解是：这些参数是对真实使用场景的抽象。 下落高度对应的是日常使用中可能遇到的落差——路缘、台阶、门槛；下落姿态对应的是这些落差被遇到时的典型方式。理解了背后的场景，才能判断标准试验对你的产品够不够、以及数据不达标时该往哪个方向改。
参数背后的场景假设
| 试验要素 | 对应的实际场景 | 如果产品实际使用超出假设 |
|---|---|---|
| 下落高度 | 路缘、门槛等常见落差 | 户外型、越野型产品需考虑更大落差 |
| 下落姿态 | 整车水平落下或单侧先着地 | 特殊结构需评估其他姿态 |
| 载荷条件 | 标称承重下的使用状态 | 加大承重规格要按实际载荷验证 |
| 着地面 | 硬质平整地面 | 实际路况更差时冲击更严重 |
| 次数 | 代表性的重复次数 | 高频使用场景需考虑累积效应 |
这张表的用法是：逐行核对你的产品实际使用条件有没有超出假设。 超出的那一行，就是标准试验覆盖不到的风险点，需要自己补充验证或者在说明书中作出使用限制。
比如户外型电动轮椅，实际可能在乡间土路、碎石路面上使用，遇到的落差和冲击频次都超过标准假设。这种情况下，只做标准规定的跌落试验，数据合格，但产品在实际使用中仍可能出问题。
姿态为什么重要
同样的下落高度，不同姿态下能量的分配完全不同。
整车水平落下时，能量由前后轮和悬挂系统共同吸收，分布相对均匀。单侧或单轮先着地时，能量集中在一侧，车架会承受扭转载荷——扭转恰恰是管件结构相对薄弱的受力形式。
所以如果产品在单侧着地的姿态下失效而水平姿态通过，问题多半出在车架的抗扭能力上，而不是整体强度不足。整改方向应当是增加抗扭刚度，比如加三角支撑、改变管件截面形状，而不是简单加厚管壁。
试验前的准备要点
一是确认载荷放置方式。 跌落时载荷的位置和固定方式对结果影响很大。载荷如果在下落过程中移位，冲击的分布就变了，结果不可重复。
二是确认可调部件的状态。 座高、脚踏位置这些会改变重心和着地顺序。和稳定性试验一样，应当明确按哪种配置执行。
三是检查紧固件的初始状态。 所有螺栓按规定扭矩紧固，并记录初始值。试验后复查扭矩，松动量本身就是有用的信息。
四是记录试验前的几何尺寸。 跌落后重新测量，变形量能反映结构的塑性变形程度，比单纯判断「有没有断」信息量大得多。
数据不理想时的整改思路
按失效形式分开看：
车架变形。 通常是整体刚度不足，需要从截面、支撑布置上改。
焊缝开裂。 工艺问题的可能性大于设计问题，先查焊接过程控制。
脚轮或前叉损坏。 冲击能量在这里集中，考虑加大过渡圆角、改变材料或增加缓冲。
连接松动。 紧固方式的问题，考虑防松措施或改变连接形式。
座椅系统失效。 载荷传递路径上的问题，检查座椅与车架的连接设计。
与冲击、疲劳的配合
跌落、冲击、疲劳三项考察的是同一个结构在不同载荷特征下的表现：跌落是高能量单次冲击，冲击是中等能量的局部作用，疲劳是低载荷的长期累积。
三项都通过才说明结构设计是均衡的。 只强化单次冲击能力而忽略疲劳，或者反过来，都会在实际使用中暴露问题。做摸底时建议三项一起安排，拿到完整的力学表现图景再定设计参数。
补充验证怎么设计
如果判断标准试验覆盖不到产品的实际使用条件，可以设计补充验证。设计时把握三点：
一是条件要有依据。 补充的落差高度、重复次数、路面条件，应当来自对实际使用场景的调查，而不是拍脑袋加严。没有依据的加严，测出来的结论也没有说服力。
二是要可重复。 补充试验的条件要写清楚到别人能复现的程度，否则数据只能自己内部用，无法对外提供。
三是和标准试验分开呈现。 补充验证的数据不能混进标准报告的结论里，应当单独成文并说明其性质。混在一起会造成对报告效力的误解。
累积效应怎么考虑
标准规定的跌落次数是代表性的，而产品在整个使用寿命中经历的次数远多于此。对于高频使用场景，可以考虑做累积验证：按标准姿态重复更多次数，观察性能衰减的趋势。
这类验证的价值在于看趋势而不是看单点。如果重复到某个次数后变形量开始加速增长，说明结构进入了损伤累积阶段，这个拐点位置对判断产品的实际寿命很有参考意义。
对于面向养老机构、医院等高使用频次场景的产品，这项信息比单次跌落是否通过更能说明产品的适用性。
我们的做法
执行跌落项目时，我们会记录着地姿态、变形量和紧固件扭矩变化，而不只给通过与否的结论。这些数据在整改阶段有用，在后续的疲劳试验出现异常时也是判断依据。
对于使用环境超出标准假设的产品，如果委托方有需要，可以按实际场景设定补充条件做验证。这类补充试验不出现在标准报告的结论里，但它回答的是「产品在真实使用中够不够结实」这个问题，而标准试验回答的是「产品符不符合要求」——这是两个不同的问题。
有需要可以把产品的使用环境描述和结构方案发过来一起看，或者直接联系：132 4819 8029。检测能力见服务介绍，产品分类见电动轮椅检测与代步车检测，标准信息见标准查询。
English version
Conclusion: test parameters are an abstraction of scenarios, not arbitrary numbers
A drop test specifies a drop height and an orientation. Many treat these as thresholds to be cleared and move on once the test passes.
A more useful reading is that the parameters abstract real use. The drop height corresponds to the height differences encountered in daily use: kerbs, steps, thresholds. The orientation corresponds to the typical way those differences are encountered. Understanding the underlying scenario is what lets you judge whether the standard test is sufficient for your product, and in which direction to work when results fall short.
The assumptions behind the parameters
Drop height corresponds to common height differences such as kerbs and thresholds; outdoor and rough-terrain products may encounter more. Orientation corresponds to the vehicle landing level or on one side first; unusual structures may need other orientations assessed. Load conditions correspond to use at rated capacity; higher capacity variants should be verified at their actual load. The landing surface is hard and level; real road conditions may produce more severe impact. The number of repetitions is representative; high-frequency use may require considering cumulative effects.
Use this as a checklist: go through each row and ask whether your product's actual conditions exceed the assumption. Any row that does is a risk the standard test does not cover, requiring either supplementary verification or a stated limitation in the instructions for use.
An outdoor powered wheelchair, for example, may be used on unpaved or gravel surfaces where both the height differences and the frequency of impacts exceed the standard assumption. Running only the prescribed drop test may produce a passing result while the product still has problems in service.
Why orientation matters
At the same drop height, different orientations distribute energy quite differently.
Landing level, energy is absorbed by front and rear wheels and the suspension together, and is distributed relatively evenly. Landing on one side or one wheel first concentrates energy on that side and imposes a torsional load on the frame, and torsion is the loading mode in which tubular structures are relatively weak.
So if a product fails in a one-sided orientation while passing level, the issue is usually torsional capacity rather than overall strength. The remedy is to increase torsional stiffness through triangulation or a change of tube section, rather than simply thickening walls.
Preparation before testing
Confirm how the load is placed and secured; if it shifts during the drop, the impact distribution changes and the result is not repeatable. Confirm the state of adjustable parts, since seat height and footrest position change the centre of gravity and the landing sequence. Torque all fasteners to specification and record the initial values, then recheck after the test, because the amount of loosening is itself useful information. Record geometric dimensions beforehand and measure again afterwards, since the amount of permanent deformation says considerably more than a simple pass or fail.
Working through a poor result
Frame deformation generally indicates insufficient overall stiffness, addressed through section and bracing changes. Weld cracking is more likely a process issue than a design one, so start with welding process control. Damage to castors or the front fork reflects energy concentration there, suggesting larger transition radii, a different material or added cushioning. Loosening of connections is a fastening issue, calling for locking features or a different joint. Seat system failure points to the load path, so check how the seat attaches to the frame.
Relationship to impact and fatigue
Drop, impact and fatigue examine the same structure under different load characteristics: a single high-energy event, a moderate localised action, and long-term accumulation at low load respectively.
Passing all three is what indicates a balanced design. Strengthening single-impact capacity while neglecting fatigue, or the reverse, will show up in service. For preliminary work we suggest running all three together and setting design parameters once the full mechanical picture is available.
How we handle it
We record landing orientation, deformation and changes in fastener torque rather than issuing only a pass or fail. These data are useful during remediation and also serve as a basis for diagnosis if the subsequent fatigue test behaves oddly.
For products whose service environment exceeds the standard assumptions, supplementary conditions based on actual use can be defined and verified on request. Such supplementary testing does not appear in the conclusions of a standard report, but it answers whether the product is robust enough in real use, whereas the standard test answers whether it conforms to a requirement. Those are two different questions.
Send us a description of the service environment together with the structural concept and we will work through it. Phone or WeChat: +86 132 4819 8029.