LIFE PREDICTION TECHNOLOGIES FOR DEFENCE SYSTEMS – A DMRL INITITIATIVE A.Venugopal Rao *, Jalaj Kumar, Sony Punnose, R.Pradyumna, and Vikas Kumar Defence Metallurgical Research Laboratory, P.O.Kanchanbagh, Hyderabad-500058, India (* Corresponding author Email: venugopal@dmrl.drdo.in) Abstract: Estimation of the remaining service life of critical components in defence hardware is emerging as an important research field, attracting the attention of researchers, designers and manufacturing agencies as a tool for ensuring the reliability of mission & safety critical systems. This paper brings out the salient aspects of the life prediction technology being evolved at DMRL, briefly outlining the numerical simulation and experimental measurement techniques. Various philosophies applied to the design and failure analysis of critical systems are discussed, with particular emphasis on methods of analysis for failure prediction and non-destructive evaluation. Keywords: Life prediction, defence components, failure, FEA, NDE 1. INTRODUCTION Estimation of the remaining service life of critical components is emerging in importance among all defence systems, owing to the extreme demands placed on materials’ performance and design optimization. The vast spectrum of damaging loads acting on these components mainly includes fatigue, creep, corrosion, fretting wear, and microstructural ageing. Life prediction of any service component is obviously a complex multidisciplinary task involving diverse expertise such as Metallurgical and Mechanical characterization of materials, Fracture Mechanics, Numerical Modeling, and Non Destructive Evaluation (NDE). DMRL has recently launched a major initiative in identifying life-critical components/subsystems in defence equipment and evolving methodologies to quantify their service life in terms of material degradation and design constraints. This paper presents an overview of the methodology involved in life prediction, the technologies essential to quantify useful life of systems, facilities at DMRL to handle the task, and typical case studies to illustrate the research in progress. 2. LIFE PREDICTION METHODOLOGY The complex task of life assessment of any real-life service component begins with their NDE in the as received condition. Techniques such as dye penetrant or radiography are employed to detect any microcracks or voids caused by the service loads. NDE is followed by a metallurgical and mechanical characterization of the material on a laboratory scale. The likely damage on the component material due to the operating environment, such as mechanical loads and temperature, is estimated through a metallographic examination of the retired/mid-life parts. Mechanical testing of the component material is then carried out, using several well-established tests such as tensile (smooth and notch), fracture toughness, fatigue, and creep. Mechanical tests characterize the constitutive behavior of the material in elastic /