3-D Shafting Calculations for Marine Installations: Static and Dynamic

2003 ◽  
Author(s):  
Wilfried Schiffer ◽  
Jean Jenzer
Keyword(s):  
Mathematical Model ◽  
Diesel Engines ◽  
Degree Of Freedom ◽  
Torsional Vibrations ◽  
Rotational Degree ◽  
Coupled Vibrations ◽  
Daily Work ◽  
Axial Vibrations ◽  
D Model ◽  
Ship Vibration

Due to the particular geometry of the crankshaft of two-stroke diesel engines and the rotational degree of freedom torsional vibrations may be calculated with a 1-D mathematical model, but all other kinds of vibrations have to be calculated with a 3-D model. This concerns also static problems. In this paper the influence of coupled vibrations on ship vibration is explained and illustrated with an example for axial vibrations and an example for external vertical forces and moments. Another example for the use of the 3-D model is the calculation of crank deflection and jack load. It can be shown that such calculations are suitable for daily work.

Anomalous metallic-like transport of Co–Pd ferromagnetic nanoparticles cross-linked with π-conjugated molecules having a rotational degree of freedom

2014 ◽  
Vol 16 (1) ◽  
pp. 288-296 ◽  
Author(s):  
Yoshikazu Ito ◽  
Kazuyuki Takai ◽  
Akira Miyazaki ◽  
Vajiravelu Sivamurugan ◽  
Manabu Kiguchi ◽  
...  
Keyword(s):  
Degree Of Freedom ◽  
Ferromagnetic Nanoparticles ◽  
Rotational Degree ◽  
Conjugated Molecules

Relationship between the Steady-Handling Characteristics of Automobiles and Their Stability

1973 ◽  
Vol 15 (5) ◽  
pp. 326-328 ◽  
Author(s):  
R. S. Sharp
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Degree Of Freedom ◽  
Nonlinear Region ◽  
Handling Characteristics ◽  
Yield Information ◽  
Turning Motion ◽  
The Stability ◽  
Three Degree Of Freedom

Analyses of the steady-state handling behaviour of an automobile and the stability of its steady-turning motion, based on a three degree of freedom mathematical model, are used to show that the steady behaviour and the stability are related similarly in the nonlinear region as in the well documented linear one. It is concluded that analysis and measurement of the steady behaviour will yield information on the stability of automobiles.

Optimal Design of a Six-Bar Linkage for an Anthropomorphic Three-Jointed Finger Mechanism

1992 ◽  
Author(s):  
Jichuan Zhang ◽  
Gongliang Guo ◽  
William A. Gruver
Keyword(s):  
Mathematical Model ◽  
Nonlinear Programming ◽  
Optimal Design ◽  
Transmission Efficiency ◽  
Degree Of Freedom ◽  
Optimal Parameters ◽  
Joint Friction ◽  
Robotic Devices ◽  
End Effectors ◽  
Human Finger

Abstract We treat the design of a three-jointed, anthropomorphic, finger mechanism for prostheses and robotic end-effectors. Based on the study of configurations for the human finger, we propose a six-bar linkage with one degree of freedom for the finger mechanism. A model of the fingertip displacement of the mechanism is derived by a vector analysis approach. We study the effects of joint friction on the transmission efficiency. By measuring the joint positions of a human finger, we develop a mathematical model of the pinching and holding configurations for the human finger. Optimal parameters for the finger mechanism are obtained by nonlinear programming based on motion posture, locus, transmission efficiency, and weight subject to geometric and bionic constraints. Simulations indicate that the mechanism is useful in a variety of prosthetic and robotic devices.

Modeling of diesel spray tip penetration during start-of-injection transients

2020 ◽  
pp. 146808742095785
Author(s):  
Xinyi Zhou ◽  
Tie Li ◽  
Ping Yi
Keyword(s):  
Diesel Engines ◽  
Transient Processes ◽  
Long Distance ◽  
Spray Tip Penetration ◽  
Start Of Injection ◽  
Initial Stage ◽  
Multiple Injection Strategy ◽  
Opening And Closing ◽  
D Model ◽  
Injection Pulse

Multiple-injection strategy that has been applied widely in diesel engines usually features a short duration for each injection pulse. As a result, the shortened injection makes the needle opening and closing transients increasingly important for spray in an injection event. Owing to the needle movement, the spray development during the transient processes is complex and quite different from the spray at the quasi-steady state. However, so far modeling of the spray development during the transient processes is far from adequate. Particularly, a theoretical zero-dimensional (0-D) spray tip penetration model considering the needle opening and sac pressurization processes as well as ambient and injection conditions during the start-of-injection (SOI) transients is still absent. In this paper, considering the sac pressurization processes, the 0-D model of spray tip penetration during the SOI transients is derived. Then, the model is validated against the experimental spray data using a long-distance microscope together with an ultrahigh speed CMOS camera. The model and experimental results show that the spray tip penetration shows a t3/2 dependence at the initial stage of injection rather than the t dependence suggested by Hiroyasu’s model. Later, the spray tip penetration shows a t3/4 dependence owing to the spray breakup, and a t1/2 dependence with the completion of sac pressurization. The models and analysis are believed to provide new insights into the transient spray behaviors and valuable reference for engineers and researchers who are considering the model-based development of next-generation diesel engines.

The Effect of Gravity and Rotor Configuration on Dry Friction Whip and Safe Rotor/Stator Clearance

2019 ◽  
Author(s):  
Rajiv Kumar Vashisht
Keyword(s):  
Mathematical Model ◽  
Fault Diagnosis ◽  
Dry Friction ◽  
Rotating Machinery ◽  
Degree Of Freedom ◽  
System Response ◽  
Rich Variety ◽  
Wide Range ◽  
Clearance Level ◽  
High Degree

Abstract A mathematical model is developed for a real rotor/stator system with high degrees-of-freedoms, multiple disks, flexible bearing supports and couplings. The safe clearance level for coasting up of the rotor is calculated for a general high degree-of-freedom rotor/stator system. The harmful phenomena of dry friction whip, which is generally observable for simple 2 degree-of-freedom Jeffcott rotors in the absence of gravity only, can be proved to exist (in real rotor/stator systems) even in the presence of gravity for a wide range of clearance levels. In case of Jeffcott rotors, by fixing the clearance and increasing the rotor spin frequency, the response of the system follows the pattern: No rub - Forward Annular Rub (FAR) - Partial Forward Whirl (PFW) - Partial Backward Whirl (PBW) - dry whip (WHIP). In case of a real rotor/stator system, at certain frequencies, the system directly jumps to dry whip. The simulated results show a rich variety of system dynamics including FAR, PFW and WHIP in case of vertical rotors where the effect of gravity is neglected. For horizontal rotors, under the effect of gravity, the system response contains multi-harmonics, chaotic responses and multi-period vibrations. Based on these responses, a robust fault diagnosis strategy can be designed to identify the rubbing action in rotating machinery.

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