Blog Posts Tagged Fatigue Module
Stress and Fatigue in Modular Implants Used in Hip Joints
Modular orthopedic devices, common in replacement joints, allow surgeons to tailor the size, material, and design of an implant directly to a patient’s needs. This flexibility and customization is counterbalanced, however, by a need for the implant components to fit together correctly. With parts that are not ideally matched, micro-motions and stresses on mismatched surfaces can cause fretting fatigue and corrosion. Researchers at Continuum Blue Ltd. have assessed changes to femoral implant designs to quantify and prevent this damage.
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.
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 […]
Random Load Fatigue
In many applications, loads applied to structures are random in nature. The sampling results of the structural response will differ depending on the data collection time. Although the stress experienced is not always high, the repeated loading and unloading can lead to fatigue. The engineering challenges in these types of applications are defining the stress response to the random load history in the critical points, and predicting fatigue damage. This is simulated with the Cumulative Damage feature in the Fatigue […]
Infamous Failures of Fatigue
If you’ve studied structural mechanics you’re probably familiar with stories of planes falling out of the sky due to fatigue (no one wants to be the engineer who designed an airplane that crashed…). Jimmy Stewart made a famous movie about that, but different from the usual horror stories of fatigue is the accident in 1919 of a storage tank that burst in Boston, spilling molasses onto the streets at 35 mph (56 km/h). The Boston Molasses Disaster, as it’s referred […]
First Keynote Video Takes Us to Babel
One of the differences between this year’s COMSOL Conference, and previous years’, is that this year we filmed a lot of it. During the next few weeks we will be publishing some of these videos for those that were there, to enjoy it once again, and for those that weren’t to get a taste of what went on. To kick these all off, I’m proud to present the first keynote video, which takes us to Babel.
Why Should You Simulate Fatigue?
The Fatigue Module, an add-on to the Structural Mechanics Module and the COMSOL Multiphysics® software, can be used to perform structural fatigue life computations for both strain-based and stressed-based fatigue. In this blog post, we discuss some of the potential application areas and benefits of fatigue testing.
Fatigue — When Cyclic Stress Produces Fractures
Many of the products that engineers design experience cyclic stresses during use that are below the material’s yield stress; unfortunately, these stresses can still be the primary reason for failure. Thus, engineers and designers must find ways of including the effects of cyclic stresses when designing products for long-term use.
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