Fatigue Analysis of an S-Hook Using SolidWorks

Welcome back to the CAE Simulation using SolidWorks series. In this blog, we delve into fatigue analysis, a crucial simulation technique used to predict the behavior and lifespan of components subjected to repetitive loading. Using SolidWorks’ simulation module, we’ll analyze the fatigue life of an S-hook commonly found in gold ornaments. 

This blog aims to guide you step-by-step through setting up and interpreting a fatigue analysis, making it ideal for students and professionals honing their skills through the Skill-Lync SolidWorks course or similar CAE training programs. 

Why Perform a Fatigue Analysis? 

Fatigue occurs when a material experiences failure after being subjected to repeated cyclic loading. For instance, an S-hook in a gold ornament is often bent and rebent to secure the ornament. Over time, this repetitive loading can lead to material failure. A fatigue analysis helps determine the number of cycles a component can endure before failure, allowing engineers to optimize designs for better durability. 

Understanding the S-N Curve 

The S-N curve (Stress vs. Number of Cycles) is fundamental in fatigue analysis. It represents the maximum stress a material can withstand for a specific number of cycles before failure. 

• Y-Axis: Maximum stress 
• X-Axis: Number of cycles 

For example, to determine the maximum allowable stress for 1,000 cycles, extend the curve horizontally from the cycle count to intersect the curve, then note the stress value on the Y-axis. 

Types of Loading in SolidWorks Fatigue Analysis 

SolidWorks provides four types of loading scenarios, each tailored for different real-world applications: 

Fully Reversed: 

• Equal magnitude of load applied in opposite directions (loading ratio: -1). 
• Example: Bending and rebending an S-hook. 

Zero-Based:

• Load applied to a maximum value, then removed entirely (loading ratio: 0). 
• Example: A doorknob subjected to repeated pulling forces. 

Loading Ratio: 

• User-defined ratio between maximum and minimum load values. 
• Example: Slightly varied forces in opposite directions. 

Find Cycle Peaks: 

• Import stress values from prior simulations to analyze complex loading scenarios. 

Steps to Perform Fatigue Analysis 

1. Static Analysis as a Prerequisite 

Before performing fatigue analysis, a static analysis must be conducted to understand the stress distribution. 

Import the S-Hook Model: 

• Open SolidWorks and import the S-hook model. 
• Rotate, pan, and zoom to ensure the model is error-free. 

Apply Material: 

• Assign Pure Gold as the material for the S-hook. 

Define Constraints: 

• Fix the base of the S-hook by selecting the relevant faces. 

Apply Load: 

• Apply a force of 50 N to the free end of the S-hook. 

Mesh and Run: 

• Use the default mesh and run the static analysis. 

2. Fatigue Analysis Setup 

Create a New Study: 

• Select Fatigue from the list of analysis types. 

Select Loading Type: 

• Choose Fully Reversed loading. 

Define Cycles: 

• Specify 1,500 cycles for the analysis. 

Assign S-N Curve: 

• Derive fatigue data from the material's elastic modulus. 
• Plot the S-N curve to ensure correctness. 

Run the Simulation: 

• Execute the analysis to determine damage and life expectancy. 

Interpreting the Results 

• Fatigue analysis provides two primary outputs: 

Damage: 

• Indicates the percentage of material damage caused by the specified number of cycles. 
• For this S-hook, the maximum damage reached 200%, meaning it failed within the specified cycles. 

Life: 

• Predicts the number of cycles the part can endure before failure. 
• The red-colored regions on the S-hook failed at 746 cycles, well below the intended 1,500 cycles. 

Insights and Design Recommendations 

The analysis revealed that the S-hook would fail before reaching the desired 1,500 cycles. To address this issue: 

Change the Material: 

Use a material with higher fatigue resistance. 

Redesign the S-Hook: 

Increase the thickness or modify the geometry to reduce stress concentration. 

Conclusion 

Fatigue analysis in SolidWorks is a powerful tool for predicting the lifespan of components under cyclic loading. By following the steps outlined above, you can identify potential failure points and optimize designs to improve durability. 

If you’re eager to master CAE in SolidWorks, explore the Skill-Lync CAE Training program, which offers hands-on training in SolidWorks CAE analysis, fatigue analysis, and more. With real-world projects and expert guidance, you’ll be equipped to tackle any engineering challenge with confidence. 

Ready to elevate your skills? Join Skill-Lync’s Full Course on SolidWorks Simulation and unlock your potential today! 

This blog is part of our ongoing CAE Simulation using SolidWorks. If you missed the previous posts, check them out here.  

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