Pulse–pressure loading effects on aviation and general engineering structures—review
Abstract This paper reviews various aspects of modeling an explosion on an aircraft, which can be extended to more general structures. A brief summary of material and structural models is given, followed by a detailed history of pulse–pressure loading models with an emphasis on free–free beams and how pulse characteristics affect a structure's response. Techniques to desensitize pulse shape effects are discussed, which culminate in the form of pressure–impulse isodamage curves. Studies using random loading models are also presented.
Dynamic response of space structures under random excitation
Abstract A method is presented to obtain the dynamic response of a simple model for space structures under random excitation. The simple model is considered as a uniform, free-free, mass-loaded, and hysteretically damped beam to simulate some space structures such as aircraft, missiles and rockets. The natural frequencies and mode shapes of the beam, which is considered as a continuous system, can be computed easily by solving a transcendental equation so that finite element analysis or some other energy methods are not required in this study. Modal analysis is then adopted to perform the random vibration analysis of the structure. The proposed method produces statistical responses such as mean square values of dynamic displacement, strain, bending moment and stress; these statistical responses are then used to estimate the reliability of the space structures.
Computational fluid dynamics as a development tool for rotary blood pumps.
Computational fluid dynamics (CFD) is beginning to significantly impact the development of biomedical devices, in particular rotary cardiac assist devices. The University of Pittsburgh's McGowan Center for Artificial Organ Development has extensively used CFD as the primary tool to analyze and design a novel axial flow blood pump having a magnetically suspended rotor. The blood-contacting surfaces of the pump were developed using a design strategy based on CFD that involved closely coupling a Navier-Stokes solver to a parameterized geometry modeler and advanced mesh movement techniques. CFD-based blood damage models for shear-induced hemolysis as well as surrogate functions describing thrombosis potential were employed to help guide design improvements. This CFD-based design approach resulted in the timely development of a pump subjected to multiple geometric refinements without building expensive physical prototypes for each design iteration. A physical prototype of the final improved pump was fabricated and experimentally analyzed using particle imaging flow visualization. The CFD predicted results correlated well with the experimental data including pressure-flow (H-Q) performance and specific flow field features. It is estimated that the present CFD-based design approach shortened the overall design time frame from an order of years to months.