## Search found 37 matches

Thu Mar 23, 2017 9:33 am
Forum: Computer-Aided Engineering Software Tools
Topic: Operating and parked condition
Replies: 7
Views: 2475

### Re: Operating and parked condition

dear jason, kindly go through my free decay responses and look at the trend of the operable and the parked states and comment on the damping ratio between the operable and parked conditions of operations, also is this the expected grap http://farm4.staticflickr.com/3792/33450496312_ecf0ba6f98_b.jpg ...
Thu Mar 23, 2017 9:21 am
Forum: Computer-Aided Engineering Software Tools
Topic: YAW INSTABILITY SIMULATION
Replies: 1
Views: 1186

### YAW INSTABILITY SIMULATION

Dear jason,

I would like to know how to simulate the yaw instability and apply brake at a particular time in the given simulation period in FAST and also how do i quantify this IN FAST for the case of the tlp, kindly reply in this regard.
Thu Mar 23, 2017 8:21 am
Forum: Computer-Aided Engineering Software Tools
Topic: Tower natural frequencies
Replies: 3
Views: 1258

### Re: Tower natural frequencies

Dear Jason, I have the understanding that the peaks of the fft gives us the natural frequencies, now given the fact i have the load history of tower base shear force variation in the 3 axes and the corresponding moments in the three axes, would it be rite to say that the peaks at which they are occu...
Sun Mar 19, 2017 1:56 am
Forum: Computer-Aided Engineering Software Tools
Topic: PSD PLOTS
Replies: 5
Views: 2249

### Re: PSD PLOTS

Dear jason, By qualitative assesment i mean the trend with respect to a particular degree of freedom,also i dont understand what does the negative decibels in the y axis imply also the AREA under this graph would give us the energy content or is it something else, also is psd only for understanding ...
Thu Mar 16, 2017 8:56 am
Forum: Computer-Aided Engineering Software Tools
Topic: Tower natural frequencies
Replies: 3
Views: 1258

### Tower natural frequencies

Dear Jason, I would like to know how do i intepret the time histories of the shear force in the base of the tower, i mean fft of this would be giving me peaks of what? also jason if i want to find out the tower natural frequencies what is the procedure for that, kindly reply in this regard, regards
Thu Mar 16, 2017 8:34 am
Forum: Computer-Aided Engineering Software Tools
Topic: yielding analysis
Replies: 1
Views: 1015

### yielding analysis

Dear jason, I paln to carry out the fatigue yielding analysis of the test23 case , so my approach is as follows the tension divided by the tether area would give me the associated stresses in the tethers across time now i want to look at the number of times the stress level exceeds the given value o...
Thu Mar 16, 2017 8:23 am
Forum: Computer-Aided Engineering Software Tools
Topic: Operating and parked condition
Replies: 7
Views: 2475

### Re: Operating and parked condition

Dear jason, When u say that the frequency would not be different for heave in operable and parked condition what could be the possible reason for this ,is it because the wind turbine weight is about 17.18% of the platform mass, or is there some other thing, also in other degrees of freedom how much ...
Thu Mar 16, 2017 8:16 am
Forum: Computer-Aided Engineering Software Tools
Topic: Free decay analysis and natural frequency
Replies: 49
Views: 12231

### Re: Free decay analysis and natural frequency

Dear jason, How do i include the other forms of damping in this model in fast so that i get a more damped reponse, which is the case with all other degrees of freedom except with that of the heave, i want this information to calculate the damping ratio, which files need to be changed so that i can g...
Thu Mar 16, 2017 8:10 am
Forum: Computer-Aided Engineering Software Tools
Topic: PSD PLOTS
Replies: 5
Views: 2249

### Re: PSD PLOTS

Dear jason,

The peak spectral time period is 10 seconds and the rotor speed is 12.1 rpm,i am getting most of my peaks below 10 Hz , and how do i qualitatively assess them, kindly reply as soon as possible, also kindly enlighten me on what u mean by rotor speed harmonics.

regards
Wed Mar 15, 2017 9:57 am
Forum: Computer-Aided Engineering Software Tools
Topic: Free decay analysis and natural frequency
Replies: 49
Views: 12231

### Re: Free decay analysis and natural frequency

Dear jason, i have enclosed my heave free decay response , kindly go through it also jaosn what would be the expected natural frequency in heave period and also what would be the damping ratio, i am getting a response which is not qualitatively consistent with the other free decay results , that is ...
Wed Mar 15, 2017 9:35 am
Forum: Computer-Aided Engineering Software Tools
Topic: PSD PLOTS
Replies: 5
Views: 2249

### PSD PLOTS

Dear jason, I would like to know the accuracy of my psd plots for the tlp case http://farm1.staticflickr.com/754/33073763150_50e897909f_b.jpg http://farm3.staticflickr.com/2827/33073767280_405cd7c5e9_b.jpg http://farm3.staticflickr.com/2825/33073771550_ca29ed3485_b.jpg http://farm3.staticflickr.com/...
Sun Mar 12, 2017 6:36 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Operating and parked condition
Replies: 7
Views: 2475

### Re: Operating and parked condition

Dear jason , Thank u for your quick reply , these are the fft plots and the platform under question is the tlp so i would just like to know the qualitative correctness of my graphs posted, is it a universal fact that pitch reponses cannot be different than those roll,also jason can u point the reaso...
Sun Mar 12, 2017 9:25 am
Forum: Computer-Aided Engineering Software Tools
Topic: Operating and parked condition
Replies: 7
Views: 2475

### Operating and parked condition

Dear jason, I am hereby enclosing the graphs of responses in comparison of operating and parked condition http://farm3.staticflickr.com/2865/32583842383_f4e8d73bd0_b.jpg http://farm3.staticflickr.com/2856/33270125921_9f4d6d14ab_b.jpg http://farm1.staticflickr.com/723/33270128381_c3d1ebb57e_b.jpg htt...
Fri Mar 10, 2017 6:13 am
Forum: Computer-Aided Engineering Software Tools
Topic: Free decay analysis and natural frequency
Replies: 49
Views: 12231

### Re: Free decay analysis and natural frequency

Dear jason, When i mean i changed to 200 m i mean the hydrodyn input for water depth not the default value taken by the fea mooring file, also jason regarding the initial platform displacements i gave about 5m surge with all the rest degrees of freeddom initial displacement zero , also i have change...
Thu Mar 09, 2017 5:46 pm
Forum: Computer-Aided Engineering Software Tools
Topic: Free decay analysis and natural frequency
Replies: 49
Views: 12231

### Re: Free decay analysis and natural frequency

Dear jason,

it is the test23 file which nrel has provided it says that it takes 200 m water depth in fea mooring analysis, so accordingly i changed my water depth to 200 , but still it dosent seem to work, kindly guide me on this aspect.

regards