88 research outputs found
A Virtual Testing Approach for Laminated Composites Based on Micromechanics
International audienceThe chapter deals with a crucial question for the design of composite structures: how can one predict the evolution of damage up to and including final fracture? Virtual testing, whose goal is to drastically reduce the huge number of industrial tests involved in current characterization procedures, constitutes one of today’s main industrial challenges. In this work, one revisits our multiscale modeling answer through its practical aspects. Some complements regarding identification, kinking, and crack initiation are also given. Finally, the current capabilities and limits of this approach are discussed, as well as the computational challenges that are inherent to “Virtual Structural Testing.
In vivo evaluation of antiseptics and disinfectants on control of Caseous Lymphadenitis: clinical, haematological, serological and microbiological monitoring
A Thermodynamically-Based Mesh Objective Work Potential Theory for Predicting Intralaminar Progressive Damage and Failure in Fiber-Reinforced Laminates
A thermodynamically-based work potential theory for modeling progressive damage and failure in fiber-reinforced laminates is presented. The current, multiple-internal state variable (ISV) formulation, enhanced Schapery theory (EST), utilizes separate ISVs for modeling the effects of damage and failure. Damage is considered to be the effect of any structural changes in a material that manifest as pre-peak non-linearity in the stress versus strain response. Conversely, failure is taken to be the effect of the evolution of any mechanisms that results in post-peak strain softening. It is assumed that matrix microdamage is the dominant damage mechanism in continuous fiber-reinforced polymer matrix laminates, and its evolution is controlled with a single ISV. Three additional ISVs are introduced to account for failure due to mode I transverse cracking, mode II transverse cracking, and mode I axial failure. Typically, failure evolution (i.e., post-peak strain softening) results in pathologically mesh dependent solutions within a finite element method (FEM) setting. Therefore, consistent character element lengths are introduced into the formulation of the evolution of the three failure ISVs. Using the stationarity of the total work potential with respect to each ISV, a set of thermodynamically consistent evolution equations for the ISVs is derived. The theory is implemented into commercial FEM software. Objectivity of total energy dissipated during the failure process, with regards to refinements in the FEM mesh, is demonstrated. The model is also verified against experimental results from two laminated, T800/3900-2 panels containing a central notch and different fiber-orientation stacking sequences. Global load versus displacement, global load versus local strain gage data, and macroscopic failure paths obtained from the models are compared to the experiments
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PICOSECOND FLUORESCENCE KINETICS IN SPINACH CHLOROPLASTS AT ROOM TEMPERATURE: EFFECTS OF MAGNESIUM ION
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ORIENTATION AND ENERGY TRANSFER STUDIES ON CHLOROPHYLL IN THE PHOTOSYNTHETIC MEMBRANE
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A NEW APPROACH TO THE THEORY OF LINEAR DICHROISM IN PARTIALLY ORDERED SYSTEMS: APPLICATION TO REACTION CENTERS AND WHOLE CELLS OF PHOTOSYN-THETIC BACTERIA
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A SINGLE-PHOTON TIMING SYSTEM FOR PICOSECOND FLUORESCENCE LIFETIME MEASUREMENTS
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FLUORESCENCE LIFETIMES OF IN VIVO CHLOROPHYLL STUDIED IN CHLOROPLASTS AND ALGAE
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PICOSECOND FLUORESCENCE KINETICS IN SPINACH CHLOROPLASTS AT LOW TEMPERATURE
Evaluation of Initiation of the Interfacial Debonding in Single Fiber Composite (Energy Balance Method Considering an Energy Dissipation of the Plastic Deformation)
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