Characterization of Impact Damage in Composite Plates

Transcription

1 Characerizaion of Impac Damage in Composie Plaes Aji Mal and Sauvik Banerjee Mechanical & Aerospace Engineering Deparmen Universiy of California Los Angeles Frank Shih Mechanical Engineering Deparmen Seale Universiy

2 Moivaion Composie srucures are ofen subjeced o foreign objec impac which may iniiae iner-ply delaminaions a deph If lef undeeced hidden damages can grow and lead o caasrophic failure of he srucure This sudy is concerned wih he deecion of low velociy foreign objec impac and he resuling damage if any in composie srucures in real ime Defecs-criical srucures require regularly scheduled inspecion and mainenance ha are cosly and ofen unnecessary Coninuous monioring of emerging flaws in advanced srucures can save cos and improve safey X-33 LH composie ank failure 3-ply specimen Impaced a.37 m/s Phoomicrograph of Delaminaion

3 Eperimenal Seup of he Impac Tes IMPACTOR REBOUND BREAK COMPOSITE SPECIMEN a b Non damaging and damaging impac ess: a Main daa acquisiion sysem b Close-up of he Insron/Dynaup impac machine

4 Theoreical Modeling Source modeling 0 0 sin 0 sin 0 S π π < < < = < < + + <. Iniial conac load / sin π = H S. Shear delaminaion Verical surface displacemen 3 4 ˆ dk dk e k k g k k f S u k k i ω ω π ω = ω + Frequency-Wavenumber domain ω ω π = ω d e u u i ˆ Re Time domain

5 Non-Damaging Impac on Plaes Aluminum Ampliude V mm Eperimenal R Theoreical a Time µ s mm Thickness: /6.6 mm. m/s impac velociy using a seel ball Consan rigger source for he eperimenal resuls Ampliude V Time µ s Typical waveforms a a 60 mm and b 00 mm away from impac locaion R b

6 Non-Damaging Impac on Plaes con. 3 layered cross-ply composie Eperimenal Theoreical degree - 60 mm Ampliude V R a Time µs degree - 00 mm Thickness: 4.3 mm 5 degree inerval 0 mm incremens Same eperimenal condiion as ha of aluminum impac ess Ampliude V R Time µs Typical waveforms a a 60 mm and b 00 mm away from impac locaion b

7 Sensor locaions on he 3 layered cross-ply plae Damaging Impac on Plaes Eernal appearance Immersion ulrasonic C-scan 4 lb impacor No major inernal damage 6 lb impacor Small den Inernal delaminaion

8 Damaging Impac on Plaes con. Typical recorded acousic emission waveforms Sensor locaed a A Sensor locaed a D 4 lb impacor 4 lb impacor Small den 6 lb impacor 6 lb impacor Waveforms from he iniial conac Waveforms from delaminaion evens

9 Waveforms from Iniial Conac Load Eperimenal Theoreical 0.30 A 0.40 A 4 lb impacor Ampliude V Ampliude Time µ s Time µ s 0.40 A 0.40 A 6 lb impacor Ampliude V Ampliude Time µ s Time µ s Waveforms from he iniial conac load for sensor locaion A

10 Waveforms from Delaminaion Iniiaion a b Theoreical signals from iniiaion of shear delaminaion a inerfaces beween a layers 4-5 b layers 6-7 Surface moion is sronger for sub-surface delaminaion The heoreical calculaions somewha conform he eperimenal resuls. The phoomicrograph showed he presence of major sub-surface delaminaion The deph of he delaminaion source can be idenified wih some confidence

11 Correlaion wih Force-Time Hisory Sensor locaion A Unloading occurs during delaminaion damage 500 Unloading Force-ime hisory Load LB Time ms Recorded signal

12 Concluding Remarks Model based predicion of far-field waveforms from impac and damage evens was successful in boh aluminum and hin composie plaes Signals from impac and delaminaion damage can be idenified from farfield waveforms using he improved eperimenal seup Failure evens can be correlaed wih sudden unloading in he force-ime curve Resuls of his research can be used o develop a more reliable nondesrucive damage deecion mehod han is currenly available Disribued broadband sensors coupled wih careful modeling can be used o develop viable healh monioring sysems for composie srucures