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J.B. Jordon M.F. Horstemeyer K. Solanki J.D. Bernard J.T. Berry T.N. Williams 《Materials Science and Engineering: A》2009,527(1-2):169-178
In this paper, the damage-induced anisotropy arising from material microstructure heterogeneities at two different length scales was characterized and modeled for a wrought aluminum alloy. Experiments were performed on a 7075-T651 aluminum alloy plate using sub-standard tensile specimens in three different orientations with respect to the rolling direction. Scanning electron microscopy was employed to characterize the stereology of the final damage state in terms of cracked and or debonded particles. A physically motivated internal state variable continuum model was used to predict fracture by incorporating material microstructural features. The continuum model showed good comparisons to the experimental data by capturing the damage-induced anisotropic material response. Estimations of the mechanical stress–strain response, material damage histories, and final failure were numerically calculated and experimentally validated thus demonstrating that the final failure state was strongly dependent on the constituent particle morphology. 相似文献
153.
Lena Magnusson Åberg Bernard Vinet Hasse Fredriksson 《Transactions of the Indian Institute of Metals》2009,62(4-5):269-273
A number of pure refractory metals have been investigated by drop-tube experiments. The cooling curves have been registered and theoretically analysed. A model for analysing the heat of fusion has been developed. It was found that the heat of fusion was approximately 50% of the tabulated value. 相似文献
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Laurent Crouzeix Jean Noël Pri Francis Collombet Bernard Douchin 《Composites Part A》2009,40(11):1732-1740
In this paper, it is proposed to apply the equilibrium gap method to orthotropic composite materials to retrieve damage laws from measured displacement fields. A finite difference implementation method is first proposed. A linear system is formed, for which the unknowns are piecewise constant orthotropic rigidities, while the measured displacements are input (known) data. In this example, a cruciform specimen is considered for biaxial test. It is shown that, by referring to FE computed displacement fields a prescribed contrast map can be identified. Corrupted artificial displacement fields obtained through non-linear simulations are also used. When considering shear damage, a procedure using estimated contrast maps to identify a damage law is validated. An experimental biaxial test on a 2.5 C/C composite is finally analysed following the proposed approach. For each unloading step, a contrast map for all moduli is obtained from full-field measurements. By assuming that the shear moduli contrasts result from a damage mechanism, one subsequently obtains damage maps, and therefore, a growth law. The results are first validated by comparing measured and FE reconstructed displacement fields, and by comparing the identified damage fields with post-processed ones. 相似文献
157.
Muran J. Christopher; Safran Jeremy D.; Gorman Bernard S.; Samstag Lisa Wallner; Eubanks-Carter Catherine; Winston Arnold 《Canadian Metallurgical Quarterly》2009,46(2):233
This study examined the relationship of early alliance ruptures and their resolution to process and outcome in a sample of 128 patients randomly assigned to 1 of 3 time-limited psychotherapies for personality disorders: cognitive–behavioral therapy, brief relational therapy, or short-term dynamic psychotherapy. Rupture intensity and resolution were assessed by patient- and therapist-report after each of the first 6 sessions. Results indicated that lower rupture intensity and higher rupture resolution were associated with better ratings of the alliance and session quality. Lower rupture intensity also predicted good outcome on measures of interpersonal functioning, while higher rupture resolution predicted better retention. Patients reported fewer ruptures than did therapists. In addition, fewer ruptures were reported in cognitive–behavioral therapy than in the other treatments. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Based on intervals bounding the uncertain initial conditions, inputs, model parameters and measurements, interval observers provide guaranteed intervals for the state trajectory. However, most of the published studies focus on methods relying on continuous-time on-line measurements, or at least, relatively fast sampling. In this study, interval state estimation methods are proposed in the situation, quite common in biological systems, where measurements are only available at discrete, and possibly rare, times. The attention is focused on defining predictors preserving the boundedness of the state variables between two measurement times assuming bounded uncertainties. The methods are tested with simulated data from continuous cultures of green algae. 相似文献
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