Defining a risk-based approach to the design and technology usage of systems to attain IT availability and recoverability requirements

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

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The Expanding Role of Echocardiography in Interventional Cardiology

European Cardiology Review ◽

10.15420/ecr.2010.6.2.71 ◽

2010 ◽

Vol 6 (2) ◽

pp. 71 ◽

Cited By ~ 3

Author(s):

Lindsay A Smith ◽

Amit Bhan ◽

Mark J Monaghan ◽

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...

Keyword(s):

Interventional Procedures ◽

Imaging Modality ◽

Interventional Cardiology ◽

Design And Technology ◽

Team Approach ◽

Medical Problems ◽

Multidisciplinary Team Approach ◽

Case Selection ◽

Optimal Imaging

Echocardiography provides excellent realtime imaging of the heart, making it the imaging modality of choice immediately before, during and after cardiac interventional procedures. It helps to guide case selection and execution of the intervention, evaluates the effects of the intervention and enables early detection of complications. Advances in the design and technology of medical devices and delivery systems, coupled with demand for alternative non-surgical therapies for common medical problems, have led to an increase in the volume, variety and complexity of non-coronary cardiac interventional procedures performed. Many of these procedures require a multidisciplinary team approach and demand optimal imaging to ensure successful outcomes. The aim of this article is to review the expanding role of echocardiography in non-coronary interventional cardiology in adults.

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