The Tsai-Wu Failure Criterion.ppt - Montana State University

The Tsai-WuTsai Wu Failure CriterionSteve TsaiEd Wu (1939-2009)(1939 2009)

The TsaiTsai-WuWu Failure CriterionTsai, STsaiS. WW. and WuWu, EE. MM. (1971)(1971). A generaltheory of strength for anisotropic materials.Journal of Composite MaterialsMaterials. volvol. 55, pppp.58-80.

The TsaiTsai-WuWu Failure Criterion

The Tsai-Wu Failure Criterion(cont.)Evaluation of Constants

Cairns’ CommentsCairnsTsai and Wu developed their tensor polynomial failurecriterion independent of Gol’denblat and Kapnov. In anyevent, Gol’denblat and Kapnov stated their criterion in theform of an infinite series, which is of little practical use. Tsaiand Wu developed the present form, including interactionparameters to a useful level for composites. The onlyregion which it does not work very well is for fibercompression failure, which is actually a geometricallydriven failurefailure, and not a true material propertyproperty. For that typeof failure, one of the “micro-buckling” types of criteria seemto be more accurate.

Use in Design

Steve TsaiDoug,We put in the mail acopy of our latestbook based onmicromechanicsand viscoelasticmatrix for lifeprediction.predictionHope you find it usefulin your researchand teaching.Steve10/12/2008

Ed Wu and Steve Tsai(L(Late2008)

Dear All,Ed Wu ppassed awayy this eveningg at 8 PM. I spentpthe dayy in the hospitalpwith Becky,y, hiswife, and daughter Susan.After his liver transplant in January, he had a good month. They chemical imbalance andtoxicity of various medicines took their tolls. He was going down hill. Yesterday, he wastold that there was nothingg that doctors could do for him. He kidneyy stoppedppfunctioning. Other organs were also breaking down.When I saw him today, he was struggling with breathing. The end was near.He was a ggood man. Veryy meticulous experimentalist.pKnew Lekhnitskii,, and fracturemechanics. We will all miss him.He left this world with many friends and colleagues. He enjoyed many sports like bicycle,motor cycle, flying, photography, and eating. The picture below was taken at China Stixlast October when he was full of ggood spiritspand appetite.ppDuringg our Januaryy 2009workshop at Stanford he stopped by to say hello.SteveStephenpW. Tsaisteve.tsai@mac.comJune 9, 2009

Ed Wu’s Obituaryt betob publishedbli h d iin ttechnicalh i l jjournalslEdward M. Wu, Professor Emeritus of Aeronautics at the Naval Postgraduate School inMonterey, CA, died on June 3 of complications following a liver transplant. He leaveshis dear wife of 47 years, Rebekah, who was his partner, in both family andprofessional life. His most prized technical publication was co-authored with his wifeand he often referred to the technical team of Wu and Wu.Wu He was very proud of hisdaughters, Susanne (Robert) Gong-Guy and Stephanie (Kenneth II) Geremia, whowent on to professional careers in dentistry and accounting, respectively. He leavessix grandchildren; Mark, Kathryn, Jonathan, and Stephen Gong-Guy of San Jose, CA,anddKKennethth III andd KaitlynK itl GGeremiai off JJupiter,it FLFL. HHe iis survivedi dbby ttwo bbrothers,thRobert Wu of Woodstock, NY and Michael Wu of Berkeley, CA and two sisters,Marlene Yang of New Port Beach, CA and Hannah Wu Lam of Seattle, WA. He waspreceded in death bypy his daughter,g, Stephanie.p

Ed Wu’s Obituaryt betob publishedbli h d iin ttechnicalh i l jjournalslProfessor Wu was born and raised in Hong Kong. He attended the University ofIllinois at Urbana/Champaign where he earned a BS in Mechanical Engineering in1960 and a MS (1963) and PhD (1965) in Theoretical and Applied Mechanics. Aftera short stay at the University of Illinois as Assistant Professor of Theoretical andApplied MechanicsMechanics, ProfProf. Wu moved to Washington University in StSt. Louis in 1967where he and Professor Steve Tsai developed and experimentally verified the TsaiWu Failure Criterion for anisotropic materials, which is now presented in compositematerials textbooks and remains widely adopted in advanced composite design inh db k suchhandbooksh as ththe FAA CCompositeit MMaterialst i l HHandbookdb k andd ththe AiAir FForce/NASA/NASAComposite Design Guide. His work on understanding fracture mechanics incomposite materials has also been incorporated into textbooks on compositematerials. Duringg this time he also ppioneered the computer-controlled,p, multi-axialtesting of anisotropic composite materials. In 1976, Professor Wu moved to theLawrence Livermore National Laboratory where he set up state-of-the-artlaboratories for static and life testing of composite materials in order to support hisresearch on statistical modeling and the quantification of composite reliabilityreliability.

Ed Wu’s Obituaryt betob publishedbli h d iin ttechnicalh i l jjournalslIIn 1984,1984 hhe movedd tto ththe NNavall PPostgraduatet d t SSchoolh l (NPS) iin MMonterey,tCA ttoteach and do research on computer-aided certification of large critical compositestructures ranging from aerospace parts to civilian infrastructure components. Hispublications at the NPS focused on the statistical nature of failure inresearch and pcomposite materials and structures. He developed the concept of statisticallydefensible reliability for composite and aerospace structures. He retired from NPSwith Emeritus rank in 2001 and continued his consulting work and original researchfor both industry and Government until his deathdeath.Professor Wu served on the Editorial Board of the Journal of Composite Materialsand was a member of the American Institute of Aeronautics and Astronautics, theAmerican Society of Mechanical Engineers, the American Society for Testing andMaterials, Pi Tau Sigma, Sigma Tau and Tau Beta Pi.

Ed Wu’s Obituaryt betob publishedbli h d iin ttechnicalh i l jjournalslIn the academic portion of his career, he earned the respect and admiration ofhundreds of undergraduate and graduate students. At the Naval PostgraduateSchool, Professor Wu mentored a generation of Naval aviators, whoseimpressions of him ranged from “a spirited pioneer who challenged us in theclassroom” to “heclassroomhe was the father I wish I could have had”.had . An avid sportsmanand pilot, he loved flying and eventually arranged a supersonic flight with one ofhis naval aviator students.Ed was also a very competitive criterium and road bicycle racer. Among hisfriends and colleagues, he is remembered by all for his “sharp wit and hisability to use humor to make a point”.ThroughoutThh t hishi professionalfil life,lif PProfessorfWWu’s’ combinationbi ti off hhumor,fairness, sensitivity, loyalty, intellect, and honesty endeared him to his family,his students, and his colleagues alike.

Ed Wu and MSU Ed visited MSU many times since Dr. Cairnscame here in 1995. He ggave specialpseminars and gguest lectures inME463 Composites, ME464 MechanicalBehavior of Materials, ME 550 Failure ofMaterials, and ME 551 Advanced Composites We were making plans for Ed to be here Fall2009 to ddeliverlillectures iin RReliability,li bili andd towork with undergraduate students for failure ofcomposite materials and structures

One of Ed’s Great LovesEd and hisDucati Paso

Ed Doug,Ed,Doug and Ed

Ed Donating Books for OurComposites Library(many more to come from his estate)

Ed at Our Cabin (Circa 2003)

h db k h th FAA C it M t i l H db k d th Ai F /NASAhandbooks such as the FAA Composite Materials Handbook and the Air Force/NASA Composite Design Guide. His work on understanding fracture mechanics in composite materials has also been incorporated into textbooks on composite materials. Duringgp p this time he also pioneered the computer .