Riga Technical University Institute of Materials and Structures

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Riga Technical University Institute of Materials and Structures Riga, Latvia AIR DAMPING INFLUENCE ON

Riga Technical University Institute of Materials and Structures Riga, Latvia AIR DAMPING INFLUENCE ON MATERIAL PROPERTIES IDENTIFIED FROM VIBRATION TESTS ВЛИЯНИЕ ВОЗДУШНОГО ДЕМФИРОВАНИЯ НА СВОЙСТВА МАТЕРИАЛА, ИДЕНТИФИЦИРОВАННЫЕ С ПОМОЩЬЮ ВИБРАЦИОННЫХ ИСПЫТАНИЙ E. Barkanov 1 and M. Wesolowski 2 1 Institute of Materials and Structures, Riga Technical University, Riga, Latvia 2 Department of Structural Mechanics, Koszalin University of Technology, Koszalin, Poland International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Contents Riga, Latvia Ø Introduction Ø Air damping influence on dynamic parameters of panels

Contents Riga, Latvia Ø Introduction Ø Air damping influence on dynamic parameters of panels with small vibration damping Ø Identification of dissipative material properties with air damping effect ØConclusions International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Introduction Riga, Latvia Due to the great importance of defining performance, reliability and safety

Introduction Riga, Latvia Due to the great importance of defining performance, reliability and safety requirements for advanced composite products and services a considerable effort has been devoted to the study of their mechanical material properties and many inverse methods based on vibration tests have been developed in the last three decades. In each inverse technique based on vibration tests, an identification of material properties is performed minimising the error functional between the experimental and numerical parameters of structural responses. Unfortunately the dynamic parameters of test specimens are very sensitive to experimental errors due to measurement inaccuracies. In the dynamic response of a structure the effect of surrounding medium is usually neglected, since it is assumed that it has a little influence on the dynamic parameters of structure and high measurement accuracy is needed to estimate air damping effect. However, if the light damped structures are under consideration (metal or laminated composite plates) the level of energy dissipation due to the contact with air should be assessed. International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Air damping influence on dynamic parameters of laminated composite panels Test specimens

Riga, Latvia Air damping influence on dynamic parameters of laminated composite panels Test specimens used in experimental analysis Material properties of test specimens used in experimental analysis International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Air damping influence on dynamic parameters of laminated composite panels Riga, Latvia An experimental

Air damping influence on dynamic parameters of laminated composite panels Riga, Latvia An experimental set-up Frequency response of plate under different air pressure Total structural loss factor: International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Air damping influence on dynamic parameters of laminated composite panels Riga, Latvia Vacuum chamber

Air damping influence on dynamic parameters of laminated composite panels Riga, Latvia Vacuum chamber Amplifier Structure vibrating in a surrounding air experiences the resisting force: Pump with vacuum regulator The energy lost per cycle: where ρ c A ω X – air density, – drag coefficient, – exposed surface area, – vibration velocity, – resonant frequency, – vibration amplitude, An experimental set-up International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Air damping influence on dynamic parameters of laminated composite panels Algorithm for

Riga, Latvia Air damping influence on dynamic parameters of laminated composite panels Algorithm for the measurements automation International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Air damping influence on dynamic parameters of laminated composite panels Air damping

Riga, Latvia Air damping influence on dynamic parameters of laminated composite panels Air damping influence on plate eigenfrequencies International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Air damping influence on dynamic parameters of laminated composite panels Air damping

Riga, Latvia Air damping influence on dynamic parameters of laminated composite panels Air damping influence on plate modal loss factors International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Air damping influence on dynamic parameters of laminated composite panels Riga, Latvia Exposed surface

Air damping influence on dynamic parameters of laminated composite panels Riga, Latvia Exposed surface area effect on plate modal loss factors International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Air damping influence on dynamic parameters of laminated composite panels Riga, Latvia Excitation amplitude

Air damping influence on dynamic parameters of laminated composite panels Riga, Latvia Excitation amplitude effect on plate modal loss factors International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Identification of dissipative material properties with air damping effect Inverse technique based

Riga, Latvia Identification of dissipative material properties with air damping effect Inverse technique based on vibration tests International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Identification of dissipative material properties with air damping effect Damping model Specific

Riga, Latvia Identification of dissipative material properties with air damping effect Damping model Specific damping capacity: where – total dissipated energy, – maximum strain energy, – modal loss factor. Energy method Modal loss factor: International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Identification of dissipative material properties with air damping effect Laminated composite panel

Riga, Latvia Identification of dissipative material properties with air damping effect Laminated composite panel Geometrical parameters: Dimensions, mm: Thickness of plate, mm: Layer stacking seguence: Material density, kg/m 3: 290 x 200 2. 6 [0]16 1546. 60 Material properties: E 1=116. 80 GPa, E 2=8. 85 GPa, G 12=4. 10 GPa, 12=0. 36 Parameters of identification: Frequency range: 0. . . 600 Hz International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Identification of dissipative material properties with air damping effect Identification parameters sensitivity

Riga, Latvia Identification of dissipative material properties with air damping effect Identification parameters sensitivity International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Identification of dissipative material properties with air damping effect Identification results International

Riga, Latvia Identification of dissipative material properties with air damping effect Identification results International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Riga, Latvia Identification of dissipative material properties with air damping effect Numerical and experimental

Riga, Latvia Identification of dissipative material properties with air damping effect Numerical and experimental results International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Conclusions Riga, Latvia Identified damping properties of a laminated composite plate are burdened with

Conclusions Riga, Latvia Identified damping properties of a laminated composite plate are burdened with the measurement error due to air damping. The air damping overestimates the results of the damping properties of a laminated composite plate. A vacuum chamber should be provided in order to improve the damping properties identification of panels with small vibration damping. International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Literature Riga, Latvia Wesolowski M. and Barkanov E. Air Damping Influence on Dynamic Parameters

Literature Riga, Latvia Wesolowski M. and Barkanov E. Air Damping Influence on Dynamic Parameters of Laminated Composite Plates. Measurement, 2016, 85, 239 -248. International conference “NDT Days 2019” Sozopol, Bulgaria 17 -21 June 2019

Slide title Workshop «INNOPIPES» Sozopol, Bulgaria 13 June 2014

Slide title Workshop «INNOPIPES» Sozopol, Bulgaria 13 June 2014