Benoit BOLZON Nanobeam 2005 – Kyoto Active mechanical stabilisation LAViSta Laboratories in Annecy working on Vibration Stabilisation Catherine ADLOFF Andrea JEREMIE Jacques LOTTIN Benoît BOLZON Yannis KARYOTAKIS Laurent BRUNETTI Franck CADOUX Claude GIRARD Fabien FORMOSA Yan BASTIAN Nicolas GEFFROY

Benoit BOLZON Nanobeam 2005 – Kyoto Introduction Future linear collider : vertical beam size of 1 nm  Movements of the two final focus quadrupoles : smaller than 0.3 nm Problem : nanodisplacement due to ground motion Goal of our study : active mechanical stabilisation of the final focus quadrupoles  Study sensors and actuators to measure nanodisplacements and achieve the required stabilisation  Model different mechanical structures because of the resonances induced by ground motion  Development of a feedback loop to stabilise the whole system

Benoit BOLZON Nanobeam 2005 – Kyoto 1.Measurements - Sensor characteristics - Ground motion - Structure vibration 2. Modal analysis - Measurements - Simulation 3. Dynamic response - Comparison measurements/simulation - Fixed-free beam - Addition of boundary conditions Outline 4. Feedback loop - Mock up - Results 5. Future prospects - New structure design - Simulation of the whole system

Benoit BOLZON Nanobeam 2005 – Kyoto 1.Measurements - Sensor characteristics - Ground motion - Structure vibration 2. Modal analysis - Measurements - Simulation 3. Dynamic response - Comparison measurements/simulation - Fixed-free beam - Addition of boundary conditions 4. Feedback loop - Mock up - Results 5. Future prospects - New structure design - Simulation of the whole system 1. Measurements

Benoit BOLZON Nanobeam 2005 – Kyoto Goal : Sensor study and ground motion study  Signal analysis : Coherence : Coherence between two sensors versus frequency Resolution : Sensor accuracy versus frequency Signal/Noise ratio PSD : Normalized signal power versus frequency RMS displacement : Displacement versus a range of frequency 1. Measurements Introduction Sensors characteristics Stabilisation of the ground Beam vibration study

Benoit BOLZON Nanobeam 2005 – Kyoto  Seismic sensors : Measurement of the ground velocity  Accelerometers : Measurement of the ground acceleration 2 types of sensors : 1. Measurements Non magnetic Introduction Sensors characteristics Stabilisation of the ground Beam vibration study

Benoit BOLZON Nanobeam 2005 – Kyoto 1. Measurements Introduction Sensors characteristics Stabilisation of the ground Beam vibration study - Conclusion : Velocity sensors can be used to measure low frequency ground motion whereas accelerometers measure ground motion only above 7Hz Very low amplitude of ground acceleration below 7Hz :  Rate Signal/Noise low  Only noise is being measured High amplitude of ground velocity below 7Hz :  Rate Signal/Noise high  Signal is being measured 0.2Hz 7Hz 100Hz Good coherence between velocity sensors Good coherence between accelerometers

Benoit BOLZON Nanobeam 2005 – Kyoto 1. Measurements Resolution Introduction Sensors characteristics Stabilisation of the ground Beam vibration study 4Hz 0.2nm 0.6nm

Benoit BOLZON Nanobeam 2005 – Kyoto Isolators : contain all the necessary electronics, vibration detection and correction devices, along with passive Isolators. Honeycomb support structure User Interface Controller : to provide communications with and diagnostics of the STACIS 2000 system Stabilisation of the ground motion with the STACIS 2000 Stable Active Control Isolation System Isolator 1. Measurements Introduction Sensors characteristics Stabilisation of the ground Beam vibration study

Benoit BOLZON Nanobeam 2005 – Kyoto Guralp sensor Accelerometers Velocity PSD 1. Measurements Passive table Active table Passive table Active table Introduction Sensors characteristics Stabilisation of the ground Beam vibration study

Benoit BOLZON Nanobeam 2005 – Kyoto 1. Measurements RMS Active bandwidth Good reduction Active table Passive table 10nm 1nm 0.5Hz 4Hz 50Hz Introduction Sensors characteristics Stabilisation of the ground Beam vibration study

Benoit BOLZON Nanobeam 2005 – Kyoto 1. Measurements Resonances induced by the excitation of the beam :  Need to use a feedback loop to damp eigenfrequencies  Usefulness of modal analysis Excitation of the beam measured Introduction Sensors characteristics Stabilisation of the ground Beam vibration study

Benoit BOLZON Nanobeam 2005 – Kyoto 1.Measurements - Sensors characteristics - Ground motion - Structure vibration 2. Modal analysis - Measurements - Simulation 3. Dynamic response - Comparison measurements/simulation - Fixed-free beam - Addition of boundary condition 4. Feedback loop - Mock up - Results 5. Future prospects - New structure design - Simulation of the whole system 2. Modal analysis

Benoit BOLZON Nanobeam 2005 – Kyoto Excitation spectrum Structural resonances Develop a know-how concerning modal analysis Ground motion Cooling system Air flows Power supply system… ( Amplified motions) 2. Modal analysis Why? Experimental Numerical Experimental/Simulation

Benoit BOLZON Nanobeam 2005 – Kyoto 2. Modal analysis Why? Experimental Numerical Experimental/Simulation Accelerometers beam Hammer Acquisition system

Benoit BOLZON Nanobeam 2005 – Kyoto ME' scope PULSE Fourier transform Mode shape 2. Modal analysis Why? Experimental Numerical Experimental/Simulation 280.5Hz Torsion

Benoit BOLZON Nanobeam 2005 – Kyoto Identify eigen frequencies Display mode shapes Mode 2: 101 Hz Mode 1: 16 Hz Modal tests on the free-fixed beam 2. Modal analysis - SAMCEF - Why? Experimental Numerical Experimental/Simulation

Benoit BOLZON Nanobeam 2005 – Kyoto Good relative accuracy ! 2. Modal analysis Why? Experimental Numerical Experimental/Simulation

Benoit BOLZON Nanobeam 2005 – Kyoto 1.Measurements - Sensors characteristics - Ground motion - Structure vibration 2. Modal analysis - Measurements - Simulation 3. Dynamic response - Comparison measurements/simulation - Fixed-free beam - Addition of boundary condition 4. Feedback loop - Mock up - Results 5. Future prospects - New structure design - Simulation of the whole system 3. Dynamic response

Benoit BOLZON Nanobeam 2005 – Kyoto External perturbation Structure Dynamic Response Ground motion Accelerations Displacements Stresses … Equations of motion 3. Dynamic response Principle Free-fixed beam Fixed-simple supported-free beam

Benoit BOLZON Nanobeam 2005 – Kyoto Check the accuracy of the numerical prediction Data used for the comparison with simulation Data used as input for the simulation 3. Dynamic response Mock-up Principle Free-fixed beam Fixed-simple supported-free beam

Benoit BOLZON Nanobeam 2005 – Kyoto Simulation parameters Structure modeled with “shell” elements Clamping system 1000 mm mm Model used : Young modulus = MPa = 0.34 (Poisson’s ratio) Volumic mass = 2825 kg/m 3 Damping : ε = 0.1 % Beam parameters : M = 830 g Lumped mass : M 3. Dynamic response Principle Free-fixed beam Fixed-simple supported-free beam

Benoit BOLZON Nanobeam 2005 – Kyoto 3. Dynamic response Comparison Simulation/Measurements Principle Free-fixed beam Fixed-simple supported-free beam

Benoit BOLZON Nanobeam 2005 – Kyoto 3. Dynamic response Goal of the study : change boundary conditions to change eigenfrequencies  Results shown : block Z-displacements of the structure to damp Z-flexion modes Principle Free-fixed beam Fixed-simple supported-free beam Mock-up

Benoit BOLZON Nanobeam 2005 – Kyoto 3. Dynamic response Principle Free-fixed beam Fixed-simple supported-free beam 34Hz 18Hz We expect amplitude of first eigenfrequency to decrease when the simple support moves away from the clamping The value of the first eigenfrequency goes up when the simple support moves away from the clamping 18Hz 20cm50cm 34Hz

Benoit BOLZON Nanobeam 2005 – Kyoto 3. Dynamic response Pick of excitation Excitation Big resonance Resonance Conclusion : In a general way, the best option is to prevent modes to be much excited, by shifting them. Obviously, the excitation spectrum must be well known… Principle Free-fixed beam Fixed-simple supported-free beam 18 Hz: Eigenfrequency when support is located at 20cm 22.5 Hz: Eigenfrequency when support is located at 30cm

Benoit BOLZON Nanobeam 2005 – Kyoto 1.Measurements - Sensors characteristics - Ground motion - Structure vibration 2. Modal analysis - Measurements - Simulation 3. Dynamic response - Comparison measurements/simulation - Fixed-free beam - Addition of boundary condition 4. Feedback loop - Mock up - Results 5. Future prospects - New structure design - Simulation of the whole system 4. Feedback loop

Benoit BOLZON Nanobeam 2005 – Kyoto « a steel beam » 2 loudspeakers 2 opposite PZT Experiments Mock up Principle of rejection Results 4. Feedback loop Accelerometer

Benoit BOLZON Nanobeam 2005 – Kyoto 4. Feedback loop Mock up Principle of rejection Results Algorithm of feedback loop developed to allow the simultaneous elimination of several resonance peaks

Benoit BOLZON Nanobeam 2005 – Kyoto Rejection of 6 resonances : (without and with rejection) Resonances of :-beam -support Mock up Principle of rejection Results 4. Feedback loop

Benoit BOLZON Nanobeam 2005 – Kyoto 1.Measurements - Sensors characteristics - Ground motion - Structure vibration 2. Modal analysis - Measurements - Simulation 3. Dynamic response - Comparison measurements/simulation - Fixed-free beam - Addition of boundary condition 4. Feedback loop - Mock up - Results 5. Future prospects - New structure design - Simulation of the whole system 5. Future prospects

Benoit BOLZON Nanobeam 2005 – Kyoto Conical shape meter long Computer Aided Design – 1 st version Φ=14cm Φ=8cm 5. Future prospects FF quad. Prediction New test bench Whole system simulation

Benoit BOLZON Nanobeam 2005 – Kyoto Prototype close to FF quadrupole design : fixed-free structure 2.5 m Representative prototype : eigen frequencies Easy Boundary Conditions : square section Adaptability to get closer and closer to the FF quadrupole: Hollow core 5. Future prospects Goal : Simulate modal analysis of the future FF quadrupole Propose new design (inner supports …) Propose new materials (composite materials …) FF quad. Prediction New test bench Whole system simulation

Benoit BOLZON Nanobeam 2005 – Kyoto 5. Future prospects Improve efficiency of feedback loop Type of sensors / actuators Location of sensors / actuators along the structure Reliability of the feedback algorithm … Simulation could be a great help !... FF quad. Prediction New test bench Whole system simulation

Benoit BOLZON Nanobeam 2005 – Kyoto Conclusion Velocity sensors can measure ground motion down to 0.1Hz We are able to predict the response of a structure  New adaptative prototype close to the future FF quadrupole design  Propose new design and new materials of the future FF quadrupole Feedback loop allows the simultaneous elimination of several resonance peaks on a reduced-size mock-up  Goal : elimination of all vibration frequencies Simulation of the whole system Mock up of the whole system Next generation of SP500 non-magnetic sensor soon available : smaller, better sensitivity (20000V/m/s!!)  May be the sensor used for our prototype