Evaluation of Force Standard Machines by using Build-up System

Transcription

1 Evaluation of Force Standard Machines by using Build-up System TC3 Round Table Nov. 24, 2010 Y.-K. Park and D.-I. Kang

2 Contents Introduction Basic theory Application examples Dynamic behavior of deadweight force standard machines Side force components of a deadweight force standard machine Future works Summary & Discussion 2

3 Keycomparison of Deadweight Force Machine Relative deviation in the recent keycomparison: < Declared uncertainty of deadweight force machine : Uncertainty of deadweight force standard machine:

4 Uncertainty of Deadweight Force Machine Uncertainty evaluation Analytically evaluated uncertainty < Unconsidered uncertainty components Interaction between transducer and force machine Parasitic force components, Dynamic behavior, etc. Present key comparison Use of single force transducer Response comparison of force transducer No measure of parasitic force component and dynamic behavior Other methods are necessary Force working group meeting (March, 2004) Discussion of future KC method Replacement of using a single transducer 4

5 Parasitic Component Measurement Dynamometer Proposed by InRIM(Dr. Ferrero) Advantage Possible to measure whole parasitic components Disadvantage Complex structure Difficult to handle Only InRIM can make the dynamometer Build-up system Advantage Simple structure Easy to handle Disadvantage Possible only for side force components 5

6 Build-up System F y 120 o FT B FT C Load button Middle platen Force transducer (FT) x Base platen Build-up system 3 force transducers Efficient method for large force (3 times of individual transducer) Build-up system set in a force machine Easy to measure disturbance signal components due to lever mechanism FT A 120 o Parasitic force component of force machine Dynamic behavior of force machine 6

7 Force and Momentum Equilibrium Load button Middle platen H Force h z F X Reactions F Z Position of F/T y B(- 3 2 a, a 2 ) C( 3 2 a, a 2 ) H r α ξ h x x A( 0, -a ) Force equilibrium + Geometrical consideration Analysis 7

8 Overall Procedure Signal from Build-up System Oscillating Component Static Component Dynamic Behavior Side Force 8

9 Example of Dynamic Motion Analysis PTB 100 kn and 1 MN force standard machines 100 kn DFM 1 MN DFM 9

10 Example of Dynamic Motion Analysis PTB 100 kn force standard machine, Load = 20 kn Y Tilt Angle, β (x o ) X Tilt Angle, α (x o ) Direction ( o ) Rotation Indicator Time (s) Time (s) +1 : Counter clockwise -1 : Clockwise Tilt Angle (x o ) Histogram Time (s) Direction ( o ) * Rotational direction changes with time 10

11 Example of Dynamic Motion Analysis PTB 1 MN force standard machine, Load = 300 kn Y Tilt Angle, β (x o ) X Tilt Angle, α (x o ) Direction ( o ) Time (s) Rotation Indicator Time (s) +1 : Counter clockwise -1 : Clockwise Tilt Angle (x o ) Histogram Time (s) Direction ( o ) * Rotational direction doesn t change with time 11

12 Example for Side Force Measurement KRISS 500 kn deadweight force standard machine Force range 13.3 kn ~ 498 kn Weights 1360 kg : Tare weight 9 x 450 kg 10 x 4500 kg Dimension Height : 15.4 m Width : 2 m Total weight : 78,600 kg Relative uncertainty : 2 x 10-5 Lifting Frame Loading Frame Hydraulic Jack Third Floor Calibration Device Second Floor 9 x kg 10 x 4536 kg 12

13 Experimental Set-up Measuring quantities 3 force signals Measurement position 0 o, 90 o, 180 o, 270 o, 360 o Force step 200, 300, 400, 500 kn Measurement procedure 3 pre-loading 2 measurements at 0 o 1 measurement at 90 o, 180 o, 270 o, 360 o Time interval 6 minutes for pre-loading and unloading 3 minutes for measurement B A C Loading frame Deadweight set Build-up system HBM MGCplus LAN 13

14 Reproducibility Difference : 2.2x x10-3 Side Force / Normal Force 1.0x x x x10-3 Fx/Fz Fy/Fz Good Reproducibility Angle (Degree) Difference : 1.6x

15 Side Force Components Average of 90 o, 180 o, 270 o and 360 o Unsymmetrical factors of a build-up system Geometrical asymmetry Sensitivity difference between F/T Etc Fy / Fz -5.0x10-4 Averaging unsymmetrical effects can be reduced -1.0x x x Fx / Fz 500 kn 400 kn 300 kn 200 kn 15

16 Future Works Verification of the method Comparison with a multi-component force sensor Dynamometer proposed by InRIM Effect analysis of build-up system structure Curvature of load button Hardness of load button Height of build-up system Etc Measurement of additional parasitic components Parasitic moment components Development and verification of measurement protocol Estimation of force machines in Korea Estimation of force standard machines of other NMIs 16

17 Summary & Discussion Summary Evaluation of deadweight force machine by using build-up system Static analysis Estimation of Side force components Dynamic analysis Pendulum motion of deadweights Discussion Should we measure parasitic components for accurate uncertainty evaluation of deadweight force machine? Is it possible to use multi-component measurement for the next force key comparison? Which parasitic component? Which method? 17