I am looking for some guidance in understanding a few things. I figured why not ask at the rocket forums because this place has a very varied group of people haha
I understand how fatigue works and what it is, but im getting some strange outputs from a numerical methods based opensource program (openFAST) when finding "time until failure in seconds"
The software uses the ultimate design load and then calulates time to failure. So what i did, since i do not have access to ANSYS or any fea software, i adjusted the ultimate design load in the software until the time to failure was 20 years. This L_ult value happened to be 806kN at a wind speed of 12.5m/s
Here is whats strange. When i use a wind speed of 4.5m/s, and use the 806kN as the ultimate load, the time to failure is 726,000 years. So, once again, i adjust the ultimate load until the time to failure is 20 years. in the slower wind speed case, the time to failure of 20 years had a ultimate load of 280kN This seems way way off. The wind speed should not affect the ultimate design load.
so this begs the question, of whats going on?
Ultimate design load is what the entire component can take before failure. IE, a popsicle stick can handle 20lbs force (bending) before it breaks.
Im not seeing how the ultimate design load can be drastically reduced to 280kN when the ONLY input to the system that changed was the wind speed..
thanks for any knowledge and advice given for this
I understand how fatigue works and what it is, but im getting some strange outputs from a numerical methods based opensource program (openFAST) when finding "time until failure in seconds"
The software uses the ultimate design load and then calulates time to failure. So what i did, since i do not have access to ANSYS or any fea software, i adjusted the ultimate design load in the software until the time to failure was 20 years. This L_ult value happened to be 806kN at a wind speed of 12.5m/s
Here is whats strange. When i use a wind speed of 4.5m/s, and use the 806kN as the ultimate load, the time to failure is 726,000 years. So, once again, i adjust the ultimate load until the time to failure is 20 years. in the slower wind speed case, the time to failure of 20 years had a ultimate load of 280kN This seems way way off. The wind speed should not affect the ultimate design load.
so this begs the question, of whats going on?
Ultimate design load is what the entire component can take before failure. IE, a popsicle stick can handle 20lbs force (bending) before it breaks.
Im not seeing how the ultimate design load can be drastically reduced to 280kN when the ONLY input to the system that changed was the wind speed..
thanks for any knowledge and advice given for this