טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentMirer Tatiana
SubjectPhysical Reliability Model Based on the System Transparence
to the Energy Flux
DepartmentDepartment of Quality Assurance and Reliability
Supervisor Professor Dov Ingman
Full Thesis textFull thesis text - English Version


Abstract

One of the crucial goals of modern engineering design is high product reliability. Traditionally, reliability engineering has developed tools for calculation of the reliability of systems which depends on reliability of its components, but estimation of the latter still poses a challenge for research. Two basic approaches to the reliability calculations are load-strength distribution and statistical assessment; the latter assumes independence of system’s elements.  As the reliability-wise important physical properties change with time under the effect of external forces, reliability analysis necessarily involves physical aspects. Thus the main subject of the proposed research is to suggest universal physical-mathematical formalism for reliability assessment.

The base of the proposed research stems from the following physical considerations.  Interaction of the system with the "environment" is considered in the proposal as a flux of energy through this system. The flux is characterized by its spectrum both at the level of input and, obviously, output. If the system is characterized by the same spectrum at its input and output, then one is called transparent. Any absorption of the flux in the system leads to changes in its internal physical properties. Therefore, the more transparent is the system, the more reliable it is. Consequently, any system can be characterized by the instantaneous spectrum of absorption. The optimal way to manage high reliability is to operate it in such regions, for which the spectrum component of the input flux coincide with absorption spectrum "windows", so, the flux absorption is minimal. As it was mentioned above, dissipation of the energy in the system changes its properties, including the absorption spectrum, which usually broadens, phenomenon, which explains the continuous failure rate increasing with time.     

In this way the research approaches the reliability assessment from the point of view of the spectral energy absorption properties. The main objective of proposed model is to make possible reliability prediction and strength distribution estimation for any load history and material properties.