S/N Fatigue Testing Sample Size Determination
S/N fatigue testing focuses on the nominal stress required for fatigue failure after a number of cycles. Stress (S) is typically plotted against the number of cycles to failure (N), displayed on a log scale. The first sample group is tested at a high peak stress........ (to read more click here)Neurostimulator Lead Testing
In this testing tip, we cover some practical aspects of neurostimulator lead testing. Samples are often preconditioned per ISO 14708-3 in a bath of approximately 9 g/l saline solution, suitable for injection, or filtered saline or ultra-pure water........ (to read more click here)3D Printed vs. Machined Parts Testing Tip
As 3D printing capabilities continue to increase and become more affordable, test engineers are increasingly using 3D printed parts in their test setups. 3D printing can produce complex, customized anatomical geometries relevant to medical device testing applications not possible with other machining methods....... (to read more click here)Acute Particulate Characterization Testing Tip
How much information are you getting from your particles? Standard laser-based particle counters are capable of providing a particle count and separating particle counts into bin sizes. This can provide important, basic information about particles shed during tracking....... (to read more click here)Advanced Amplitude Control
When testing devices that feature unique material behavior, it may not be possible to control the test directly using simple load, position or strain control. This is especially apparent when relationships between two control parameters change drastically under cyclic loading....... (to read more click here)How fast can I run my axial fatigue test samples?
With 400M and 600M cycle testing becoming increasingly common, there is increased need for accelerated frequency testing to obtain test data and meet critical deadlines. Determining the maximum frequency at which a test can be performed depends on several factors. ..... (to read more click here)How do you use the Amplitude Controller to control a non-linear system?
When a system has a linear response you can run it in traditional feedback control and use the Amplitude Controller to boost the command as needed to obtain the desired waveform levels. Where this control approach comes up short is when the system response is non-linear or discontinuous..... (to read more click here)How do you set up the Amplitude Controller?
Last week we talked about how the Amplitude Controller could automatically alter the command drive signal so that the desired peaks are being met. This week we will talk about techniques for setting up the Amplitude Controller so that it does its job correctly..... (to read more click here)What is Amplitude Control?
Test system controllers that feature peak detection software usually have Amplitude Control algorithms built into the software. The purpose of the Amplitude Controller is to control the maximum and minimum levels the test system applies to the specimen during the test. Since the Peak Detection software is already monitoring the peaks..... (to read more click here)How to verify motion at high frequency?
Most medical devices and materials exhibit frequency-dependent behavior. This sometimes presents a challenge when testing at high frequencies (40-60Hz). Device mass or material loss modulus..... (to read more click here)Sample Size: How can you maximize the number of samples you put on an axial fatigue tester?
The required sample size for durability testing is on the rise due to increased confidence and reliability standards. This means equipment optimization is key.... (to read more click here)What are Peak and Underpeak Limit Detection?
Most modern test system controllers feature some sort of peak detection software. The purpose of the peak detection is to measure the maximum and minimum levels the transducers see during the test. Monitoring the signal peaks is used to verify that the desired test parameters are being achieved.... (to read more click here)For an axial test do you control the applied displacement to the specimen or the applied load?
It depends on whether you are trying to impart a strain amplitude or a stress amplitude into the device. Generally if you want to achieve a desired strain you control the displacement (deflection) applied to the device. Figure I shows a test frame .... (to read more click here)