Experimental Dynamic Substructuring Coupling and Decoupling - Application to Ampair 600 Wind Turbine - Siamand Rahimi Good afternoon everyone and welcome to this presentation. First I will like to give you a outline of the presentation.

Introduction Presentation outline Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Introduction Presentation outline Introduction Dynamic Substructuring (DS) Experimental DS Ampair 600 Wind Turbine Experimental modeling Assembly results Conclusions Recommendations I will start with the concept of Dynamic Substructuring. For the one which are not really in this field I will try to give an idea about the notion of DS and Experimental DS Then I will show and describe the test bed which those techniques are applied to I will also illustrate the modeling steps and will show the results Then I will have a little chat on Experimental DS difficulties And I will finish with the conclusion and recommendations

Dynamic Substructuring 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Dynamic Substructuring Schematic overview [1] Subdividing the structure into substructures Modeling each substructure separately Assembling the models using DS techniques Imagine a structure as shown here. It is too large and complex to be analyzed as one piece. Dynamic substructuring simply divides the structure into smaller components Model them analyst them separately And Putting them back together analytically [1] Figures from Daniel J. Rixen, Dynamic Substructuring Concepts, Tutorial, IMAC 2010.

Dynamic Substructuring 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Dynamic Substructuring Advantages of DS Local and global structure analyzing and optimizing Design groups work independently and exchange information Applying DS means having a design tool advantage which Can help to analyse and optimize a structure Locally and globally Can let different design groups to work on their own and exchange information

Experimental DS Substructure modeling Analytically (FEM) 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Experimental DS Substructure modeling Analytically (FEM) Experimentally (FRF) Before applying DS we need to model the substructures Modeling can be done analytically or experimentally Imagine a structure shown If one measures the response at discrete internal and interface points due to a impact Putting all those responses in a matrix a model is going to be obtained

Experimental DS Frequency Based Substructuring (FBS) 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Experimental DS Frequency Based Substructuring (FBS) having the experimental models of the substructures one can use FBS to assemble the substructures

Experimental DS Advantages of Experimental DS 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Experimental DS Advantages of Experimental DS Cheaper and faster for too complex substructures Include all structural information such as damping When dealing with too complex structures the Experimental derived models And give a better representation of the structure

Ampair 600 wind Turbine Experimental DS Test bed initiated by SEM 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Ampair 600 wind Turbine Experimental DS Test bed initiated by SEM Advancing experimental DS Studying and evaluating existing methods Identifying generalized modeling techniques Providing guidance on their use It is 600 W Ampair wind turbine supported on a trampoline At the end some generalized modeling techniques would be identified

Ampair 600 wind Turbine Here at TU-Delft Iterative approach 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Ampair 600 wind Turbine Here at TU-Delft Iterative approach First iteration: three blades with the hub Here at tu delft we have chosen an iterative approach the first iteration consists of assembling the blades with the hub and will be discussed in more details here.

Ampair 600 wind Turbine Blade-Hub Assembly 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Ampair 600 wind Turbine Blade-Hub Assembly Blades are glass reinforced polyester structures

Experimental modeling 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Experimental modeling Blade models Mass loaded at interface with fixture Fully measured at interface 14 internal nodes are measured The blade is decoupled (Fixture is subtracted analytically) Blade is locally exercised (worked) The joint stiffness and damping are included in the blade model Blades are glass reinforced polyester structures The mode shapes are represented better More modes are identifiable in the frequency range of interest Also things like bolts an screw are included in the model

Experimental modeling 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Experimental modeling Blade models Measured Regenerated (Synthesized) The first graph shows a driving point measurement with and without the bracket together with the validation The second graph shows the same information for a cross point FRF. Because of mass removal the average amplitude is increased and the peaks are shifted to right except for the modes which are stiffer due to the fixture This will ensure that the blade is a good representation of the reality

Experimental modeling 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Experimental modeling Several blade modes

Experimental modeling 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Experimental modeling Lumped Hub model Lumped model (rigid body) Hub inertia properties 3.85 0.0014 - 0.0386 0.0 0.0201 0.0003 - 0.0002 0.0288 0.0004 0.0212 The first hub model is a lumped model which assumes the hub to be rigid We need the hub inertia properties to lump it and they can measured using impact measurement. The inertia properties are than measured with respect to marked point here are given here An unbalance of 10 grams at the end of one of the junctions could cause this

Experimental modeling 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Experimental modeling Full Hub model Full model Cyclic symmetric The second hub model is obtained directly from the interface hub measurement The hub is cyclic symmetric which means that when we ….. Which is a very fast and robust modeling technique for the hub Doing this insures reciprocity of the full hub model and avoid ….

Assembly results Assembly One blade model used three times 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Assembly results Assembly One blade model used three times In the local coordinates of the hub Having all models we can do the assembly now The assembly is done in the local coordinates of the hub joint which coincide with the global coordinates of the blade.

Assembly results Coupling variants Regenerated Blade-Lumped Hub (RBL) 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Assembly results Coupling variants Regenerated Blade-Lumped Hub (RBL) Regenerated Blade-Full Hub (RBF) Measured Blade-Lumped Hub (MBL) Measured Blade-Full Hub (MBF) Validation

Assembly results Coupling variants CMIF we see here four things 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Assembly results Coupling variants CMIF we see here four things First the regenerated blade model gives a very poor prediction The lumped hub model gives very good results at the low frequency region The full hub model improve the results at the higher frequency region MBL and MBF are the best results

Assembly results MBL versus MBF 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Assembly results MBL versus MBF MBF MBL 1st mode 18.8 [Hz] 15.64 % 20.9 [Hz] 4.4 % 2nd mode 25.4 [Hz] 8.1 % 29.0 [Hz] 3.5 % 3rd mode 52.3 [Hz] 3.41 % n/a 4th mode 65.5 [Hz] 0.15 % 74.3 [Hz] 1.1 % 5th mode 98.3 [Hz] -0.55 % 106.4 [Hz] 0.2 % 6th mode 117.0 [Hz] 1.00 % 118.0 [Hz] 2.4 % 7th mode 125.0 [Hz] 0.23 % 123.8 [Hz] 8.1 % 8th mode 144.3 [Hz] 1.43 % 159.4 [Hz] 9th mode 151.6 [Hz] 0.86 % 167.6 [Hz] 0.5 % 10th mode 178.8 [Hz] 1.19 % 182.4 [Hz] 1.65 % If we compare MBL With MBF we see that: Up to 185 HZ

Assembly results MBL Modes 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Assembly results MBL Modes

Assembly results MBL Modes 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Assembly results MBL Modes

Assembly results MBL Modes 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Assembly results MBL Modes

Assembly results MBF Modes 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Assembly results MBF Modes

Assembly results MBF Modes 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Assembly results MBF Modes From the identified modes some have a very low modal damping which is maybe caused by damping in the joint which is not correctly included in the blade model. The reason could be the damping mechanism in the joint which varies due to the hub mass. preferably use a fixture which resembles the adjacent substructure mass

1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Conclusion Fixture doesn’t just mass loads the interface but also rigidifies the connection area. The hub mass is very dominant in the low frequency region The hub elastic modes are important at the higher region The regenerated (synthesized) blade model is not feasible and the experimentally derived model gives a much better result which can be caused by; close modes, damping which is distributed in a non proportional way, the absence of proper lower and higher residual terms, too complex higher modes which not are not easily identifiable

Recommendations Questions left unanswered 1. Introduction 2. Dynamic Substructuring (DS) 3. Experimental DS 4. Ampair 600 Wind Turbine 5. Experimental modeling 6. Assembly results 7. Conclusions 8. Recommendations Recommendations Questions left unanswered Would the blade model change if a much heavier fixture was used? Were the results still the same if all three blades were modeled and used in the assembly?

Thank you

Thank you

Assembly results MBL versus MBF

Experimental DS Difficulties Rigid Body Dynamic and Noise Impact measurement when elastic and rigid body modes are well separated Interface Deformation Method (IDM) The method which we have used to measure the inertia properties can be applied if the rigid body and elastic modes are well separated Coupling is done through a single node and to get the rotational DoF’s IDM is used. IDM maps the measured point to virtual point in least square sense an with that RDOF are obtained and noise is also