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UID:0-318@aerospace.technion.ac.il

DTSTART;TZID=Asia/Jerusalem:20191113T163000

DTEND;TZID=Asia/Jerusalem:20191113T173000

DTSTAMP:20230527T132043Z

URL:https://aerospace.technion.ac.il/events/development-of-an-ultrasonic-m
 ethod-for-measuring-the-ablation-rate-and-temperature-distribution-within-
 a-silica-phenolic-thermal-protection-material/

SUMMARY:Development of an Ultrasonic Method for Measuring the Ablation Rate
  and Temperature Distribution within a Silica-Phenolic Thermal Protection 
 Material
DESCRIPTION:Lecturer:Aleksander Zibitsker\n Faculty:Department of Aerospace
  Engineering\n Institute:Technion – Israel Institute of Technology\n Loc
 ation:Classroom 165\, ground floor\, Library\, Aerospace Eng.\n Zoom: \n A
 bstract: \n Details: \n Re-entry and hypersonic vehicles\, as well as rock
 et motors\, are exposed to extreme heat loads\, shear forces and chemicall
 y aggressive gasses. To protect the structure of the vehicle\, ablative th
 ermal protection system (TPS) materials are commonly used.  As these mate
 rials protect the vehicle\, they sacrifice themselves and\, as a result\, 
 change in thickness and shape. This adversely affects the insulation and a
 erodynamic performance of the vehicle.  Hence\, during testing and certif
 ication of ablative TPS materials it is critical to monitor their ablation
  performance. The main objective of the current research is to use an ultr
 asonic technique to monitor the material ablation process of silica-phenol
 ic TPS material. Moreover\, due to the large temperature gradients within 
 the material\, a method for correction of temperature influence on speed o
 f sound was sought after.\nMany ablative TPS materials\, including silica-
 phenolic\, have anisotropic structure\, which causes a diffuse backscatter
  of ultrasonic pulses propagating through the material.  Since these ultr
 asound reflections come from the internal material micro-structure\, they 
 are received earlier than the echo from the ablating surface. Thus\, they 
 can be used to correct the decrease in speed of sound as the material temp
 erature rises.\nThe current study will show how monitoring the temperature
  dependent behavior of the backscattered echoes was used to correct the sp
 eed of sound (SOS) change in the material. Additionally\, based on the exp
 erimental measurements of the SOS temperature dependence\, evaluation of t
 ime-varying temperature profiles within the material will be presented. Th
 e performance of the developed method is evaluated based on several ablati
 on experiments using an oxy-acetylene torch apparatus. Verification of the
  developed method is based on post-test micro-CT and ultrasound scans of t
 he ablated samples.
CATEGORIES:Seminars
LOCATION:Classroom 165\, ground floor\, Library\, Aerospace Eng.

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TZID:Asia/Jerusalem

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DTSTART:20191027T010000

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