?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.relation=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F19495%2F&rft.title=Highly+Nonlinear+Solitary+Waves+for+Rail+Buckling+Prevention&rft.creator=Cai%2C+Luyao&rft.description=One+of+the+major+structural+problems+in+the+railroads+made+of+continuous+welded+rails+is+buckling+in+hot+weather+and+breakage+or+pulling+apart+in+cold+weather.+Buckling+is+usually+caused+by+the+high+compressive+stress+due+to+thermal+load+or+weak+track+conditions%2C+and+sometimes+vehicle+loads.+The+prevention+of+track+buckling+is+related+to+the+determination+of+the+temperature%2C+called+rail+neutral+temperature%2C+at+which+the+net+longitudinal+force+in+the+rail+is+zero.%0D%0A%09In+the+project+presented+in+this+thesis+we+investigated+the+capability+of+a+novel+sensing+system+to+indirectly+measure+applied+stress+in+rails+and+predict+incipient+buckling.+This+system+consists+of+a+simple+and+cost-effective+transducer%2C+recently+developed+at+the+University+of+Pittsburgh%2C+which+enables+the+generation+and+detection+of+highly+nonlinear+solitary+waves+(HNSWs)%2C+which+are+compact+non-dispersive+mechanical+waves+that+can+form+and+travel+in+highly+nonlinear+systems+such+as+granular%2C+layered%2C+or+porous+materials%2C+where+they+are+conventionally+generated+by+the+mechanical+impact+of+a+striker.%0D%0ATo+prove+the+feasibility+of+this+novel+system+to+predict+buckling+temperature+or+measure+applied+stress%2C+we+investigated+numerically+and+experimentally+the+interaction+between+solitary+waves+propagating+along+a+chain+of+granular+particles+and+slender+beams+of+different+shapes%2C+lengths%2C+and+boundary+conditions.+We+found+that+the+geometric+and+mechanical+properties+of+the+beam+or+thermal+stress+applied+to+the+beam+alter+certain+features+of+the+solitary+waves.%0D%0A%09Overall%2C+the+work+presented+in+this+thesis+was+articulated+in+four+main+tasks%3A+1)+literature+review%3B+2)+create+a+semi-analytical+model%3B+3)+design+and+test+new+transducers%3B+and+4)+conduct+a+series+of+experiments+including+a+field+test+at+the+University+of+California%2C+San+Diego.%0D%0A%09This+HNSWs+approach+does+not+require+many+electronic+accessories+and+shows+a+good+sensitivity+to+the+properties+of+the+material+that+is+at+the+interface+with+the+chain+of+particles.+Moreover%2C+it+only+observes+the+propagation+of+solitary+waves+within+the+transducer+without+the+waves+in+the+rail.&rft.date=2013-09-24&rft.type=University+of+Pittsburgh+ETD&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.language=en&rft.identifier=http%3A%2F%2Fd-scholarship-dev.library.pitt.edu%2F19495%2F1%2Fcailuyao_etd2013.pdf&rft.identifier=++Cai%2C+Luyao++(2013)+Highly+Nonlinear+Solitary+Waves+for+Rail+Buckling+Prevention.++Master's+Thesis%2C+University+of+Pittsburgh.++++(Unpublished)++