Peak stress is a highly localized stress concentrated at a point of discontinuity in a load path. Imagine it as a pressure spike in a specific area of a material under load. This isn't a uniform stress across the entire material, but rather a significantly higher stress value at a particular location.
Understanding Peak Stress
A common example is the high stress found at the root of a bolt's thread. The change in geometry—the transition from the cylindrical shaft to the threaded portion—creates this stress concentration. Other examples include:
- Welded Joints: High localized stresses often develop at the weld's interface due to the change in material properties and geometry. This is often analyzed using methods like the Peak Stress Method (PSM) https://www.sciencedirect.com/science/article/pii/S1877705818302704.
- Contact Points: Where two surfaces meet, peak stresses frequently occur due to concentrated forces. Refining the mesh in Finite Element Analysis (FEA) models can help to better resolve these high stress concentrations https://community.sw.siemens.com/s/question/0D54O000061xnlGSAQ/high-peak-stresses-in-contact-problem.
- Cartilage Damage: Repeated impacts with sufficient force (peak stress of at least 2.5 MPa and stress rate of at least 30 MPa/sec) can cause damage to cartilage https://pubmed.ncbi.nlm.nih.gov/10632454/.
It's important to note that while FEA software often shows high peak stresses, these values might not always reflect real-world behavior due to simplifications in the model. Careful consideration of the model's limitations is crucial when interpreting peak stress results https://www.eng-tips.com/threads/peak-stress-in-solid-fe-models.211759/.
Types of Stress
While peak stress is a specific type of stress, it's important to remember other stress types exist. These include:
- Compressive Stress
- Tensile Stress
- Shear Stress
- Bending Stress
- Torsion Stress
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