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LSU Doctoral Dissertations

Damage

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Full-Text Articles in Mechanical Engineering

Degradation And Fatigue Involving Dissipated Processes, Md Liakat Ali Jan 2015

Degradation And Fatigue Involving Dissipated Processes, Md Liakat Ali

LSU Doctoral Dissertations

Irreversible material degradation due to cyclic mechanical loading is investigated utilizing the concept of thermodynamic entropy, plastic strain energy, and temperature slope measurement. Uniaxial tension-compression and fully-reversed bending fatigue tests are performed over a wide range of loading conditions with metallic and composite materials subject to both constant- and variable-amplitude loading. A methodology is developed for the estimation of the fatigue fracture entropy (FFE) and fatigue toughness of metallic specimens in a rapid fashion. It is found that the FFE and the fatigue toughness of each material tested are within a small band. The value of FFE is found to ...


Multiscale Viscoplastic-Viscodamage Analysis Of Shape Memory Polymer Fibers With Application To Self Healing Smart Materials, Amir Shojaei Jan 2012

Multiscale Viscoplastic-Viscodamage Analysis Of Shape Memory Polymer Fibers With Application To Self Healing Smart Materials, Amir Shojaei

LSU Doctoral Dissertations

Self-healing smart material systems have been introduced into the research arena and they have already been deployed into industrial applications. The Close-Then-Heal (CTH) healing mechanism for polymeric self-healing systems is addressed herein and then a new generation of Shape Memory Polymer (SMP) based self-healing system is proposed in this work. This system incorporates SMP fibers to close the cracks while the embedded Thermoplastic Particles (TPs) are diffused into the crack surfaces upon heating and provide a molecular level of healing. The SMP fiber manufacturing procedure is briefly addressed in this work in which the bobbin of SMP fibers are heat ...