医疗器械疲劳测试提示

Fatigue testing is utilized for characterizing material properties and specimen behavior during cyclic loading. Understanding the durability and limits of the device allows medical device manufacturers to bring safe and reliable products to market.

Given the complex regulation and high risk of medical device applications, 疲劳测试 must be stringently performed to the appropriate stress levels, 样本大小, 并根据定义良好的测试协议制定标准.

如何进行医疗器械S/N疲劳测试?

Medical device 疲劳测试 focuses on the nominal stress required for failure after a number of cycles. Stress (S) is typically plotted on a log scale against the number of cycles to failure (N), 也被称为S/N疲劳测试. 

在S/N疲劳试验中, the first sample group is tested at high peak stress (or strain in a variation of the test) where failure occurs after a low number of cycles. Subsequent samples are tested at decreasing stress levels until a statistically significant number of samples do not fail in the specified number of cycles. The fatigue threshold is the highest stress at which a runout (non-failure) occurs.

如何确定样本量 

Determining the appropriate 样本大小 is a balance between the number of tests needed for the highest level of statistical confidence and the cost of developing the test specimens. The number of samples needed depends on the standard deviation and desired levels of statistical significance. Power analysis calculators are available online to help you determine the best 样本大小 for your application. 

矫形器械疲劳试验的样品和试验结果

Orthopedic devices experience various forces during their use inside the body, 包括疲劳, 扭转和磨损. The number of samples needed for an orthopedic device fatigue test may vary based on device type, 材料及更多. 

During bone plate 疲劳测试, for example, six samples are often used. Four of the samples are tested to failure at the higher load levels, and two are used as runouts. 如果产品或工艺有微小的变化, only the runout samples may need to be retested to confirm that the changes did not impact device performance.

Sample design and failure detection methods for Intravascular Device Fatigue 测试

对于没有谓词的血管内装置测试, the required sample count and number of test levels are often higher than with an orthopedic device. For example, a strutted stent design might use a six or twelve-specimen fixture for each test level.

To achieve better granularity on the cycles (N) and stress (S) axes, six or more test levels might be used with each six- or twelve-specimen test setup. While the number of tests might be six, the number of specimens tested could be 72. 当测试多个样本时, it is useful to incorporate a failure detection mechanism so that specimen failures can be tracked without the need for constant visual inspection.

Test coupons for intravascular device fatigue tests are often diamond-shaped for stents and valves and might be either cut directly from a device (1:1 scale) or scaled up, so they are easier to handle if device dimensions are very small.

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我们的 medical device experts work diligently to help your company mitigate risk and bring safe products to patients worldwide. im体育APP to discuss how we can help with your medical device 疲劳测试. 

How to create a test protocol for medical device 疲劳测试 projects

确保任何规模的疲劳试验项目的成功进行, it is critical to perform the testing in line with a clear and thorough test protocol. Engaged Expert Maciej Jakucki outlines how to structure your document, analyze requirements and define acceptance criteria in our 医疗器械试验规程 article. 

我应该使用哪种医疗器械疲劳测试系统?

There are different systems available for 疲劳测试 of medical devices.  While most 21st-century 疲劳测试 applications leverage linear motor technology, each technology possesses unique characteristics that make it indispensable to medical device testing. 我们的 医疗器械疲劳试验系统的比较 文章解释了伺服液压的区别, Servopneumatic, 单相和多相直线电机测试系统. 

医疗器械机械测试该做与不该做

For more guidance on 疲劳测试 and mechanical test programs for medical devices, 阅读我们的文章 医疗器械机械测试的注意事项.