Analyzing the Bolted Flange Joint of the F1 Engine Nozzle: A Detailed Engineering Simulation

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Description: In this blog post, I will walk you through an in-depth analysis of the bolted flange joint that connects the mid and lower parts of the F1 engine nozzle, a critical component of the Saturn V's first stage, powered by five F1 engines. This analysis was part of my learning experience in the CornellX course on ‘A Hands-on Introduction to Engineering Simulation’ via edX, under the guidance of Andy Sadhwani.

Introduction to the Project

The primary objective of this project was to build a non-linear finite element model in ANSYS to assess the margin of safety of the flange bolts and to determine the gaps that develop between the jointed parts when the assembly is loaded. The focus was on a specific part of the F1 engine nozzle, as depicted in the accompanying images.

Left: The actual F1 engine on display at the National Air and Space Museum. (Photograph by Mike Peel www.mikepeel.net)
Right: The ANSYS model of the mid and lower parts of the nozzle, showing the 100 bolts used in the analysis.

Nozzle Model of 100 Bolts


Material Properties

Understanding the material properties is crucial for accurate simulation. The materials used in this analysis are:

Material

Young’s Modulus (psi)

Poisson’s Ratio

Coefficient of Thermal Expansion (per °F)

300 Series Stainless Steel

2.9E+7

0.27

1E-5

A-286 Steel

2.9E+7

0.31

9.5E-6

Pressure and Forces

The pressure within the nozzle due to the exhaust gas was calculated using 1D gas dynamics, varying linearly along the nozzle axis. At the exit (z=0), the pressure is 12.17 psi, and at the entrance to the mid-nozzle, it is 47.72 psi. To simplify the model, the regeneration channels were omitted, and a free body diagram was used to deduce equivalent forces on the mid and lower nozzle. These forces were modeled as two separate 1000 lbf forces. The gas temperature is 700°F, causing thermal strain, and the bolt was pre-loaded to 50% of its breaking strength.

Key Highlights of the Analysis

1.      Building the Non-Linear Finite Element Model in ANSYS:

    • The model was developed to include the critical components: the mid and lower parts of the nozzle and the bolted flange joint.
    • Non-linear elements were used to accurately simulate the behavior of the materials under load and thermal conditions.

2.      Assessing the Margin of Safety:

    • The simulation aimed to determine the margin of safety for the flange bolts, ensuring they can withstand the operational stresses without failure.

3.      Analyzing Joint Gaps:

    • The model helped in understanding the gaps that develop between the jointed parts when subjected to loads, which is crucial for ensuring the integrity and performance of the nozzle assembly.

4.      Simplification and Efficiency:

    • The model was simplified by reducing the 200 bolts and nuts to half a bolt for a more efficient analysis.
    • Manual contacts were added for enhanced accuracy, ensuring the simulation results closely matched real-world behavior.

Project Results

Flange Bolt Stress Distribution

The ANSYS simulation revealed the stress distribution on the flange bolts. The color-coded representation indicates varying stress levels, with red areas showing the highest stress concentration. This visualization is crucial for identifying potential points of failure and ensuring that the bolts can withstand the applied loads without exceeding their yield strength.



Joint Gap Analysis

The simulation also provided insights into the gaps that develop between the jointed parts under load. Understanding these gaps helps in evaluating the joint's integrity and ensuring a proper seal is maintained during operation.

Mode of the Flange Analysis

In this image, the mode of the flange analysis illustrates the deformation pattern and modes of vibration of the flange under operational loads. This is essential for understanding the dynamic behavior of the joint and ensuring it can withstand fluctuating stresses without failure.


Detailed Results

1.      Total Deformation: The total deformation of the joint under the given load conditions was found to be 27.9 mm. This value is critical for understanding how much the structure will deform under operational conditions and helps in ensuring that the deformation stays within acceptable limits to maintain structural integrity.

2.      Gap Between Flanges: The gap between the flanges was measured to be 0.253 mm. This gap is important to monitor as it can affect the seal and overall performance of the joint. Ensuring the gap is minimized helps in maintaining the efficiency and safety of the engine.




Conclusion

This hands-on project that significantly enhanced my technical skills in engineering simulation and provided valuable insights into industrial applications. Special thanks to Andy Sadhwani for his mentorship throughout the course.

This hands-on project not only enhanced my technical skills but also provided valuable industrial insights. Big thanks to Andy Sadhwani for the mentorship!

#EngineeringSimulation #ANSYS #CornellX #EdX #FiniteElementAnalysis #SaturnV #Engineering #LearningExperience

For further insights and technical discussions, feel free to reach out and connect. Stay tuned for more engineering adventures and analyses!

Agweu Remmy Duncan
Finite Element Analysis Enthusiast | Mechanical Engineer | Aspiring Aeronautical Engineer
LinkedIn Profile | Blog


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