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Full-Text Articles in Mechanical Engineering
Frequency Driven Phasic Shifting And Elastic-Hysteretic Partitioning Properties Of Fractional Mechanical System Representation Schemes, Jerzy T. Sawicki, Joe Padovan
Frequency Driven Phasic Shifting And Elastic-Hysteretic Partitioning Properties Of Fractional Mechanical System Representation Schemes, Jerzy T. Sawicki, Joe Padovan
Mechanical Engineering Faculty Publications
Based on the Louiville–Riemann fractional formulation of lumped hysteretic mechanical system simulations, asymptotic-type relationships are derived. These are employed to determine how such operators, which act as viscoelastic elements, partition system energy into conservative and nonconservative components. Special emphasis is given to: (a) determine how operator order serves to weigh such a splitting, (b) determine how partitioning affects system phasing and amplitude response, and (c) to establish how conservative and nonconservative effects modulate during a given system cycle. The generality of the undertaken approach is such that multi-element fractional Kelvin Voigt formulations subject to spectrally rich inputs can be handled, …
On-Line Free Form Surface Measurement Via A Fuzzy-Logic Controlled Scanning Probe, Ming Chang, Paul P. Lin
On-Line Free Form Surface Measurement Via A Fuzzy-Logic Controlled Scanning Probe, Ming Chang, Paul P. Lin
Mechanical Engineering Faculty Publications
This paper presents a system and methodology for on-line free form surface measurement via a scanning contact probe installed on a CNC (computer numerical control) machine. The scanning probe provides more sampling points than any traditional touch trigger type of probes used on CNC machines, and better measuring accuracy than laser displacement sensing or structured lighting. The presented measuring system's main advantage is that the number of measured points can vary with the change of surface curvature. To improve the measuring stability and continuity, fuzzy logic control, in lieu of traditional PID control, is employed. As a result, the …
On The Detachment Of Step-Tapered Doublers: Part 2—Evolution Of Pressure Loaded Structures, Anette M. Karlsson, W. J. Bottega
On The Detachment Of Step-Tapered Doublers: Part 2—Evolution Of Pressure Loaded Structures, Anette M. Karlsson, W. J. Bottega
Mechanical Engineering Faculty Publications
One-dimensional edge debonding of layerwise step-tapered patches from both flat and cylindrical structures subjected to applied pressure is studied in the context of the general formulation presented in Part 1. Numerical simulations based on analytical solutions of the problems of interest are performed and intricate results presented in the form of threshold curves/delamination paths for various taper angles and support conditions. Configurations corresponding to full contact of the debonded segments, edge contact of the debonded segments and no contact of the debonded segments of the evolving composite structure are included in the model and found to significantly affect the predicted …
On The Detachment Of Step-Tapered Doublers : Part 1—Foundations, W. J. Bottega, Anette M. Karlsson
On The Detachment Of Step-Tapered Doublers : Part 1—Foundations, W. J. Bottega, Anette M. Karlsson
Mechanical Engineering Faculty Publications
One-dimensional edge debonding of layerwise step-tapered patches from both flat and cylindrical structures is examined. The problems are approach from a unified point of view, as propagating boundary problems in the calculus of variations, with the models for both flat and curved structures being formulated simultaneously. The effects of a contact zone adjacent to the bonded region are incorporated as is the phenomenon of edge-point contact. The formulation results in a selfconsistent representation of the various intact and debonded segments of the composite structure comprised of a multilayer patch and a base structure. It concurrently yields the conditions which establish …
The Presence Of Edge Contact And Its Influence On The Debonding Of Patched Panels, Anette M. Karlsson, W. J. Bottega
The Presence Of Edge Contact And Its Influence On The Debonding Of Patched Panels, Anette M. Karlsson, W. J. Bottega
Mechanical Engineering Faculty Publications
A formulation is presented which accounts for configurations of debonding patched cylindrical panels for which the edge of the debonded segment of the patch maintains sliding contact with the corresponding base structure. The formulation is incorporated with that which accounts for configurations for which a contact zone is present and for which no contact between the debonded segments of the patch and base structure occurs during debonding. Analyses are performed for two types of loading conditions: Applied circumferential tension and applied internal pressure. Results of numerical simulations based on analytical solutions of the problems of interest are presented in the …
The Dynamics Of Rotor With Rubbing, Jerzy T. Sawicki, Joe Padovan, Rabih Al-Khatib
The Dynamics Of Rotor With Rubbing, Jerzy T. Sawicki, Joe Padovan, Rabih Al-Khatib
Mechanical Engineering Faculty Publications
This paper presents the description of some phenomena associated with dynamic behavior of rotors interacting with stationary components. Numerical simulations show rotor vibration spectrum rich in subharmonic, quasi-periodic, and chaotic vibrations. The nonlinear calculation techniques are applied to demonstrate the changes of the vibration patterns for different operating conditions. Some conclusions are discussed with regard to unique characteristics of rub-induced rotor response, initial conditions, as well as appropriate ranges of system parameters. Of special interest are the changes in the apparent nonlinearity of the system dynamics as rubs are induced at different rotor speeds. In particular, starting with 2nd order …