University of Arizona Civil Engineering Professor Tribikam Kundu is part of a team that\u2019s designing a way to test thermal protection system (TPS) tiles on a military version of the Space Shuttle. <\/p>\n
Kundu spent the summer at Wright-Patterson Air Force Base in Dayton, Ohio working on ways to non-destructively test the tiles. The work was done in labs run by the Non Destructive Evaluation Branch of the Air Force Research Laboratory.\n<\/p>\n
Kundu was testing the tiles for poor adhesion or internal cracks. The project is aimed at developing a real-time, on-line monitoring system for the tiles on a military version of the space shuttle. <\/font> <\/font> Professor Kundu and his graduate students are continuing the project on the UA campus by using computer models to further develop the testing technique and to determine the number and position of sensors needed to make it work most efficiently. The project is being conducted under the supervision of the Air Force Materials and Manufacturing Directorate.<\/font> <\/font> In 2003, the Space Shuttle Columbia was lost when a breach in its TPS on the leading edge of the wing allowed super-hot gasses destroy the Orbiter during re-entry.<\/p>\n \u201cWhen the space shuttle re-enters the atmosphere, the air friction generates enough heat to melt any kind of metal,\u201d Kundu explained. \u201cThe special silicon-carbide foam tiles are attached to the outer surface of the shuttle. They protect it from the high heat generated when the shuttle re-enters the Earth\u2019s atmosphere. The inside of the tile is like a sponge with many air pockets that serve as shields for the outside heat.\u201d<\/p>\n Three things can cause the tiles to break down:<\/p>\n \u00e2\u20ac\u00a2 The tiles can delaminate from a space vehicle (such as the shuttle). During re-entry partially delaminated tiles can rip away, exposing the metal underneath.<\/p>\n \u00e2\u20ac\u00a2 The tiles can develop internal cracks that provide pathways for heat to reach the underlying metal.<\/p>\n \u00e2\u20ac\u00a2 The tiles can be damaged by collisions with some of the millions of tiny space junk particles that are leftover debris from previous missions. Even a BB-sized particle traveling at high speed could damage a tile. <\/font> This past summer, Kundu and Air Force researchers demonstrated that ultrasonic signals generated by piezo-electric transducers can be used to test how well the tiles are bonded to the shuttle or if they contain hidden cracks. The signals were generated by a transducer and sent to a receiver through an aluminum test frame.<\/p>\n \u201cIf you have perfect bonding and no cracks, the signal energy will be low at the receiver,\u201d Kundu said. \u201cAs soon as the energy level goes up, that\u2019s an indication of a delamination defect.\u201d<\/p>\n Ultrasonic waves are what engineers call \u201celastic waves.\u201d We hear elastic waves as sound waves between about 20 Hz and 20 KHz. Above 20KHz, they\u2019re called ultrasonic waves. These waves can travel through the air like sound waves or they can travel through solid materials, such as the shuttle tiles. When they travel through the tiles, they generate a small amount of stress.<\/p>\n \u201cWe have demonstrated this system as a proof-of-concept at the Air Force Research laboratory,\u201d Kundu said. \u201cNow the question is, \u2018How do we design a system to make it work in the real world?’\u201d That\u2019s now the focus of his ongoing research.<\/p>\n Kundu also is working on ways to detect when the tiles are hit by space junk so they can be inspected for damage.<\/p>\n <\/font> \u201cWe can permanently mount a sensor on the bottom of each tile that will send a signal when it is hit,\u201d he said. The sensors would be wireless so engineers would not have to worry about running hundreds of feet of cable to the tiles. \u201cBut we may not need a sensor on every tile,\u201d he explained. \u201cMaybe we only need a sensor every few rows.\u201d This could be a 3-by-3 area, covering nine tiles or a 6-by-6 area covering 36 tiles.<\/font> \u201cAlthough we\u2019re using DPSM to model the elastic wave propagation through a tile structure, it can be applied to a wide variety of engineering problems,\u201d he said.<\/p>\n Kundu worked on the DPSM method during summer research projects between 1998 and 2004 at the Ecole Normale Superieure in Cachan, France with Professor Dominique Placko. They are now writing a book about DPSM.<\/p>\n Kundu and Professor Douglas Adams of Purdue University are working on the thermal-protection tile project in collaboration with the research group leader Dr. Kumar Jata of the Air Force Research Laboratory at Wright-Patterson Air Force Base.<\/font> <\/p>\n","protected":false},"excerpt":{"rendered":" University of Arizona Civil Engineering Professor Tribikam Kundu is part of a team that\u2019s designing a way to test thermal protection system (TPS) tiles on a military version of the Space Shuttle. Kundu spent the summer at Wright-Patterson Air Force Base in Dayton, Ohio working on ways to non-destructively test the tiles. The work was […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[],"class_list":["post-42247","post","type-post","status-publish","format-standard","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/42247"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=42247"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/42247\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=42247"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=42247"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=42247"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
Kundu is attacking these problems with a computer modeling technique called DPSM (Distributed Point Source Method). This is a numerical analysis technique that is simpler and faster than methods now commonly used by engineers, such as finite element analysis.<\/p>\n