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Dynamic deformation and failure mechanisms in polycrystalline ceramics are investigated through constitutive modeling and numerical simulation. Two ceramics are studied: silicon carbide (SiC, hexagonal crystal structure) and aluminum oxynitride (AlON, cubic crystal structure). Three dimensional finite element simulations incorporate nonlinear anisotropic elasticity for behavior of single crystals within polycrystalline aggregates, cohesive zone models for intergranular fracture, and contact interactions among fractured interfaces. Boundary conditions considered include uniaxial strain compression, uniaxial stress compression, and shear with varying confinement, all at high loading rates. Results for both materials demonstrate shear-induced dilatation and increasing shear strength with increasing confining pressure. Failure statistics for unconfined loading exhibit a smaller Weibull modulus (corresponding to greater scatter in peak failure strength) in AlON than in SiC, likely a result of lower prescribed cohesive fracture strength and greater elastic anisotropy in the former. In both materials, the predicted Weibull modulus tends to decrease with an increasing number of grains contained in the simulated microstructure.

Dynamic deformation and failure mechanisms in polycrystalline ceramics are investigated through constitutive modeling and numerical simulation. Two ceramics are studied: silicon carbide (SiC, hexagonal crystal structure) and aluminum oxynitride (AlON, cubic crystal structure). Three dimensional finite element simulations incorporate nonlinear anisotropic elasticity for behavior of single crystals within polycrystalline aggregates, cohesive zone models for intergranular fracture, and contact interactions among fractured interfaces. Boundary conditions considered include uniaxial strain compression, uniaxial stress compression, and shear with varying confinement, all at high loading rates. Results for both materials demonstrate shear-induced dilatation and increasing shear strength with increasing confining pressure. Failure statistics for unconfined loading exhibit a smaller Weibull modulus (corresponding to greater scatter in peak failure strength) in AlON than in SiC, likely a result of lower prescribed cohesive fracture strength and greater elastic anisotropy in the former. In both materials, the predicted Weibull modulus tends to decrease with an increasing number of grains contained in the simulated microstructure.

This paper covers the development of an integrated nonlinear dynamic model for a variable cycle turbofan engine, supersonic inlet, and convergent-divergent nozzle that can be integrated with an aeroelastic vehicle model to create an overall Aero-Propulso-Servo-Elastic (APSE) modeling tool. The primary focus of this study is to provide a means to capture relevant thrust dynamics of a full supersonic propulsion system by using relatively simple quasi-one dimensional computational fluid dynamics (CFD) methods that will allow for accurate control algorithm development and capture the key aspects of the thrust to feed into an APSE model. Previously, propulsion system component models have been developed and are used for this study of the fully integrated propulsion system. An overview of the methodology is presented for the modeling of each propulsion component, with a focus on its associated coupling for the overall model. To conduct APSE studies the de- scribed dynamic propulsion system model is integrated into a high fidelity CFD model of the full vehicle capable of conducting aero-elastic studies. Dynamic thrust analysis for the quasi-one dimensional dynamic propulsion system model is presented along with an initial three dimensional flow field model of the engine integrated into a supersonic commercial transport.

This paper covers the development of an integrated nonlinear dynamic model for a variable cycle turbofan engine, supersonic inlet, and convergent-divergent nozzle that can be integrated with an aeroelastic vehicle model to create an overall Aero-Propulso-Servo-Elastic (APSE) modeling tool. The primary focus of this study is to provide a means to capture relevant thrust dynamics of a full supersonic propulsion system by using relatively simple quasi-one dimensional computational fluid dynamics (CFD) methods that will allow for accurate control algorithm development and capture the key aspects of the thrust to feed into an APSE model. Previously, propulsion system component models have been developed and are used for this study of the fully integrated propulsion system. An overview of the methodology is presented for the modeling of each propulsion component, with a focus on its associated coupling for the overall model. To conduct APSE studies the described dynamic propulsion system model is integrated into a high fidelity CFD model of the full vehicle capable of conducting aero-elastic studies. Dynamic thrust analysis for the quasi-one dimensional dynamic propulsion system model is presented along with an initial three dimensional flow field model of the engine integrated into a supersonic commercial transport.

1Letters to a Daughter

By Hubert Bland

<i>Letters to a Daughter</i> is a collection of essays proffering ‘fatherly advice’ in the form of a one-sided correspondence. Each of these takes the form of a response to a question that a young woman who is about to enter adult society might pose. The fictional daughter in <i>Letters to a Daughter</i> is named ‘Alexa.’ The author, Hubert Bland, a columnist and political activist, dedicated the book to his daughter, Rosamund Edith Nesbit Bland. <br><br> While married to the author Edith Nesbit, Mr. Bland had a lifelong extramarital relationship with Alice Hoatson, the birth mother of Rosamund - Edith, Alice and Hubert lived together ‘openly’. Rosamund wrote <i>The Man in the Stone House</i>, a novel about a young woman’s relationship with her parents, and the children’s book <i>Moo Cow Tales</i>; she also wrote the children's book <i>Cat Tales</i> with her adoptive mother, Edith Nesbit - Summary by Brian Fullen

Moo Cow Tales is a collection of four children's short stories written during the 1890's by young author Rosamund Edith Nesbit Bland. In 1904, Rosamund co-authored another book of children's stories, Cat Tales, with her adoptive mother, Edith Nesbit. Rosamund Edith Nesbit Bland also wrote the 1934 novel, The Man in the Stone House, about a young woman's relationship with her parents. Each story in Moo Cow Tale uses the literary device of personification. The book from which this recording is made has many fine illustrations by Evelyn Stuart Hardy (1866-1935), an artist whose work graced so many publications including children's books that featured pop-ups and moveable pictures. (Summary by Brian Fullen)

3Moo Cow Tales (Version 2)

By Rosamund Edith Nesbit Bland

Four short children's stories regarding a family's barnyard cows and their comical adventures. - Summary by Alicia S