Integrating Next Generation Technology: Mechanical Failure Modes

Note: This is part four of a five-part series on integrating next-generation technologies into your design workflow. Click the links to read parts one, two, and three.

A well-known fact in the engineering community is that predicting product performance early in the design process helps to make good design decisions. SOLIDWORKS provides the tools to verify form, fit and function, and SOLIDWORKS Simulation helps close the loop by providing design validation tools. More importantly if design and simulation are done concurrently, early on in the design process, it not only helps to make informed design decisions but also mitigates downstream risks in terms of cost and wasted time.

In Part 3 of this series, you saw how topology optimization drove our design process of this payload mounting bracket. A first pass simulation shows that it is strong enough to withstand the functional requirements, but is this enough to justify real-life performance?

Strength test is addressing just one of the many types of mechanical failure modes. Under real-world conditions, a product may encounter loads that can cause one or more of the following types of common structural failure: 1. Material failure, 2. Frequency /vibration failure, 4. Fatigue failure, 4. Buckling failure and 5. Thermal failure.

Vibration failure can often be overlooked in the design validation process. In reality most of the loads that act on a product are actually not static but can be dynamic enough to cause what is called “Load Amplification.” The strength of a product can be easily compromised, which in turn, can affect product life (Fatigue failure). In this blog, you will see and learn about some of these failure modes on the payload mount that can help answer the fundamental question: Will the design hold up to vibrational loading and how will that affect product life?

A frequency analysis is the first step towards addressing vibration issues. The results of a frequency analysis (shown below) report the natural frequencies of a design and its subsequent mode shapes.These are also referred to as resonant frequencies. So if an external load on the system is also a vibration source, and if that vibration coincides with one or more of the resonant frequencies of the design, load amplification is likely and so it’s worth investigating how the design responds to such a physical phenomenon.

The plots below show the mode shapes for some select resonant frequencies. What’s important to understand is that each mode shape is showing us in what direction the mass of the design would participate if an external vibration source with the same resonant frequency tries to shake up the structure.

Vibration analysis is an extension of frequency analysis and provides us with more detailed data such as stress, displacement, strains, velocities and accelerations. Specific guidelines for doing vibration tests and simulations can be found in applicable standards in every industry. Below are some examples:

A sample shock test qualification for aircraft electronics enclosure testing would look something like the image below. We won’t go into specifics as it’s beyond the scope of this blog.

Here is another example of a sheet metal cabinet for U.S highway truck vibration test requirements.

Watch the video below to get a behind-the-scenes tour of how vibration analysis using SOLIDWORKS Simulation is done on the payload mount example. The video also illustrates how subsequent fatigue analysis can help predict the life or durability of the product under vibrational loads.

Vibration and Fatigue analysis provide insight into the real-world performance of a design, giving us more confidence in our product. Having verified form, fit, function and product performance, the next logical step is to get some functional prototypes made. In Part 5, which also wraps up this series, we will explore an online services tool called 3DEXPERIENCE Marketplace. This is a one-stop shop to get parts manufactured quickly with trusted vendors. To watch all videos in this series, click here or the below banner.