In such industry that is facing tough market competition like automotive industry, having product durability issue during prototype testing and validation stage will be quite challenging, or sometime even quite frustrating. Especially when you are the testing engineer or project manager that has to ensure that all prototype testing and validation is done within the schedule.
When a durability issue occurs during this period, then there is a chance that we have to repeat the whole process of durability test or even to postpone the delivery date. It will be very difficult and it may become a significant loss to postpone the delivery date, since the new production tools may have been prepared by engineering team, the new component from the suppliers are already in the inventory, and the previous automotive model may not be produced anymore due to non availability of component from suppliers.
One of the most popular durability issues quite challenging to be characterised is durability issue related to vibration environment.
In automotive product, vibration environment is mainly caused by two sources, the automotive engine and the road vibration.
How to optimize the time needed to counter measure our product durability issue due to vibration?
Below are some tips that can be considered to handle durability issue due to vibration.
Listing Up the Probability of Root Causes
This step is most common first step that need to be performed.
Having Fault Tree Analysis will be very useful to see the big picture and understand below information.
What are the activities that need to be done
Manpower needed to be deployed
Timeline
Other necessary information like the time elapsed during durability testing before the issue happens or any other symptom observed before the issue happens, such as noise, excessive vibration, etc.
Probability of Manufacturing Defect
Before jumping to conclusion that this durability issue is caused by improper design, it is common to try to evaluate first if the product durability issue may come due to manufacturing imperfection.
In this case, some of below activities may be needed:
Product Dimensional Inspection. There are many tools that can be used to run dimensional inspection, starting from simple vernier caliper to more complex Coordinate Measuring Machine (CMM), or even going to the sophisticated 3D scanner with couple or even more camera units.
Material Properties Inspection. It is also common to run material properties inspection by material laboratory to ensure that all the properties of material used to manufacture the product are within the specification mentioned by design engineer at fabrication drawing. This inspection process may include hardness testing, tensile testing, microstructure, etc.
Fractography. When this durability issue involves fracture or crack propagation, then it will be highly recommended to run fractography evaluation to determine the probability of fracture mode (fatigue, creep, etc). It is also important the capability of testing engineer to conserve the "fractured area" before sending it to the material laboratory for evaluation, which will determine the accuracy of fractography. This fractography may be done by using high magnification camera or even microscope. Some material laboratories even use Scanning Electron Microscope (SEM) to perform fractography.
Product Response Characteristic Evaluation
Commonly, once we can confirm that the durability issue is not caused by manufacturing defect, then we may proceed to evaluate the design. The first thing that we may want to do is to evaluate the characteristic of the parameters related to durability issue.
If this is related to vibration, then most of the time we may need to run vibration measurement by using vibration sensors, such as accelerometers.
But if the issue is related to fracture or crack propagation, then strain gage may also be involved.
The idea of having this response characteristic analysis is to find in more details about the root cause such as resonance, engine order, engine harmonics, etc.
Product Dynamic Characteristic Evaluation
Based on the product response evaluation, if we suspect that the issue is caused by the frame structure of the product, then we may want to evaluate the dynamic characteristic of the frame structure.
By running a series of FRF Testing and also Modal Analysis of the frame structure, we should be able to see the dynamic characteristic of the frame structure and correlate it with the response characteristic.
Other than running FRF Testing and Modal Analysis, similar type of testing and analysis can be performed virtually by using 3D CAE simulation software. But in order to be able to use the 3D CAE simulation accurately, we have to be sure that the 3D CAE model is validated.
Structural Design Improvement
After evaluating the dynamic characteristic of the frame structure and correlating it to response characteristic, we should be able to understand which area that we can target for improvement and how we are going to improve it.
We can start to list up our improvement ideas. Basically, we have few options below:
To manufacture prototype unit for each improvement idea and run physical durability/vibration testing for each prototype unit. But this option may need very long duration. If we can't afford to run long duration testing for each prototype unit, we may want to try to perform accelerated testing. We may calculate and define higher level of vibration in order to reduce the testing duration.
To virtually test the improvement ideas based on the actual data during the Dynamic Characteristic Evaluation. By using this method, we can narrow down our improvement ideas into only few options or even only one. After that, we can manufacture the prototype and run the durability testing.
Similar with previous option, just that we use 3D CAE software to run virtual testing to our virtual improved prototype. Compare to previous option, this method may give us bigger improvement area to play. But as mentioned before, we have to be sure that the 3D CAE model is validated first.
ETS Solutions Asia provides complete suite of products below, starting from hardware to software, for each of development stage of your product development lifecycle.
Product Response Characteristic Evaluation
Simcenter Scadas Data Acquisition Hardware
Scadas Lab
Scadas Mobile
Scadas Recorder
Scadas XS
Simcenter Test Lab Data Acquisition and Analysis Software
Test Lab Signature Acquisition
Test Lab Signature Throughput Processing
2. Product Dynamic Characteristic Evaluation
Simcenter Test Lab Data Acquisition and Analysis Software
Test Lab FRF Testing
Test Lab Modal Analysis
3. Structural Design Improvement
Simcenter Test Lab Data Acquisition and Analysis Software
Test Lab Modification Prediction
Simcenter 3D CAE
ETS Electrodynamic Shaker
Vibration Controller
Accelerometer
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