All posts by Mateusz Stec
Modeling Fatigue Failure in Elastoplastic Materials
Imagine bending a metallic paper clip back and forth until, after a few repetitions, it breaks entirely. This is one example of fatigue failure, the most common type of structural collapse. In more severe cases, such failure can lead to collapse or malfunction in structures like car exhaust pipes and aircraft jet engines. To better understand and predict fatigue failure in elastoplastic materials, we can use the COMSOL Multiphysics® software to accurately model both the materials and the fatigue process.
How to Model Contact Fatigue in COMSOL Multiphysics®
Damage occurs in bearings, gears, rails, and cams due to a damage mechanism called contact fatigue. This happens in assemblies when two parts in contact experience a time-dependent contact pressure. When the transferred load is too high, and after numerous load cycles, a piece of the surface material can flake off and leave a small crater. This phenomenon is called spalling or pitting. With the COMSOL Multiphysics® software, we can model contact fatigue and predict failure in these components.
Reaching New Heights in Pole Vaulting: A Multibody Analysis
Pole vaulting is one of the most difficult events to master in track and field. Athletes must be able to run fast, be strong enough to elevate their body by holding the pole, and have excellent body control in order to change position while airborne. Analyzing the science behind this sport offers greater insight into the mechanisms that ensure success.
How to Obtain Fatigue Model Parameters
When simulating fatigue, you are faced with two main challenges. The first is to select a suitable fatigue model for your application and the second is to obtain the material data for the selected model. I recently addressed the first challenge in the blog post “Which Fatigue Model Should I Choose?“. Today, I will address the second challenge and discuss how you can obtain fatigue model parameters.
Which Fatigue Model Should I Choose?
The most frequent question we get regarding the Fatigue Module is “Which fatigue model should I use in my simulations?” There is no straight answer to this question, since fatigue is not based on an exact differential equation, but on engineering observations that lead to different physical models. The applicability of each model can depend on factors such as material and loading type. Today, I will discuss different approaches for fatigue model selection and the applicability of the different models.
Modeling Thermal Fatigue in Nonlinear Materials
Engineers simulating fatigue in nonlinear materials are faced with two challenges. You must correctly represent the material behavior with a constitutive relation and find a fatigue model that captures the life-controlling mechanism. Both challenges require a thorough material knowledge. Today, we will address these challenges when modeling thermal fatigue in nonlinear materials.
Submodeling: How to Analyze Local Effects in Large Models
Computer aided engineering (CAE) helps us understand how mechanical systems work before they are physically realized. In order to properly reflect the reality, we continuously increase the modeling complexity when we simulate, validate, or optimize our applications. A simple technique to improve a model is to increase the number of finite elements that in turn create more evaluation points. The hardware and simulation time, however, may limit the size of the model, and other solutions are necessary — such as […]
Fatigue Prediction Using Critical Plane Methods
Research on fatigue started in the 19th century, initiated following failing railroad axles that caused train accidents. In a rotating axle, stress varies from tension to compression and back to tension in one revolution. The load history is simple because it is uniaxial and proportional. Fatigue can then be evaluated with the S-N curve, also known as the Wöhler curve, which relates stress amplitude to a component’s life. In many applications we deal with multiaxiality and non-proportional loading. In this […]
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