Gopinath Chattopadhyay

Development of lifetime warranty policies and models for estimating costs

In todays fiercely competitive products market, product warranty has started playing an important role. The warranty period offered by the manufacturer/dealer has been progressively increasing since the beginning of the 20th Century. Currently, a large number of products are being sold with long-term warranty policies in the form of extended warranty, warranty for used products, service contracts and lifetime warranty policies. Lifetime warranties are relatively a new concept. The modelling of failures during the warranty period and the costs for such policies are complex since the lifespan in these policies are not defined well and it is often difficult to tell about life measures for the longer period of coverage due to usage pattern/maintenance activities undertaken and uncertainties of costs over the period. This paper focuses on defining lifetime, developing lifetime warranty policies and models for predicting failures and estimating costs for lifetime warranty policies.

REVIEW OF LONG-TERM WARRANTY POLICIES

A large number of products are now being sold with long-term warranty policies. This is mainly due to fierce competition in the market and customer demand. Offering long-term warranty results in additional complexities in estimating costs associated with warranty servicing due to the uncertainties associated with usage, preventive maintenance and warranty servicing strategies. This paper reviews various long-term warranty policies and mathematical models for estimation of warranty servicing costs.

Development of a unified railway track stability management tool to enhance track safety

Track buckling is a serious problem for railways. High longitudinal rail stresses contribute to problems such as track buckling, rail joint failure, rail breakage and failure of turnouts. The direct and indirect costs of track buckling problems are very high. The influences of rail temperature, stress-free temperature (SFT) and lateral misalignment of track on track buckling need comprehensive investigation. In this paper, an experimental design comprising strain gauges, thermocouples and rail stress sensors has been implemented on the Queensland Rail heavy haul 60 kg/m rail network. A new creep measurement technique using internal rail stress has been developed. The changes in rail neutral temperature due to the variation of actual rail temperature and the occurrence of rail creep in straight and curved track is quantified. Modes of differences of SFT in the two rails at a location, and of SFT in straight track and in curved track are discussed. The relationship of SFT to rail temperature is also presented. Daily variation in rail temperature due to ambient air temperature is presented. Field trials showed that SFT can vary by 2–3 ℃ during the day. Based on this finding and the derivation of an equation for change of SFT, an improvement in utilising rail creep measurements for assessing track condition has resulted. This finding suggests that it is possible to determine the SFT throughout a day rather than just a single SFT value. This paper also presents a simple track stability management tool that is based on two major parameters, namely rail stress and track resistance. Each parameter in the tool has been given three levels of value to determine the required preventive measures. Overall, the tool decides the need for speed restriction during hot weather based on the quantified parameters from the field trials and rail standards.

Soil Factors Behind Inground Decay of Timber Poles: Testing and Interpretation of Results

Inground decay is a major problem associated with the reliability and safety of timber poles. In modeling inground decay for effective maintenance strategies for timber poles, it is important to identify soil factors that are influential to the inground decay. This paper investigates some of the important influential soil factors and testing methods for those factors.

Research Methodology for Evaluation of Top of Rail Friction Management in Australian Heavy Haul Networks

Managing the coefficient of friction at the wheel/rail interface through wheel flange/gauge face lubrication is an accepted practice in railway systems. However, the coefficient of friction between the top of rail and wheel tread is not well addressed using this method, with traction, braking and some steering forces causing significant rail and wheel damage. Top-of- rail friction management uses friction modifiers to control the coefficient of friction within a defined range, and is being used in some North American rail networks with beneficial results. In Australia, there has been limited use of top-of-rail lubrication and where it is applied, it is mainly utilised to improve steering forces and mitigate wheel squeal. This research project sought a holistic understanding of top-of-rail lubrication and management of wheel/rail friction in the Australian context. A systematic approach for experimentation and analysis of the application of a friction modifier was developed in this study. The approach utilised an engineering analysis based on experimental results and publications and a numerical study for three-dimensional analysis. Vehicle system dynamics and wheel/rail operating conditions were then modelled through GENSYS simulation to understand variations in wear index with respect to friction conditions at the wheel/rail interface.

Long Term Warranty and After Sales Service

Reliability of products is becoming more and more important due to tough competition in the product market. The effective ways to ensure reliability are to consider design, manufacturing, and after sales services. One way to signal the reliability through after sales service of the product is by offering better warranty terms. The warranty period offered by the manufacturer/dealer has been progressively increasing since the beginning of the 20th century. Currently, a large number of products are being sold with long term warranty policies in the form of lifetime warranty, extended warranty, warranty for used products, and service contracts and performance based maintenance contracts policies. These types of warranties are becoming more and more popular as these provide assurance for a longer reliable service life, protection of customers against poor quality and the potential high cost of failure occurring in products life cycle. Formulation of attractive policies and cost models for these warranties is important to the manufacturer/service agents for estimating future costs to build it into the sales/contract price. This chapter recollects warranty basics in the beginning and then introduces the a number of currently available long term warranty policies to develop foundation for further studies on long term warranty and service contract policies and cost models in the subsequent chapters.

Life cycle management for railway bridge assets

Railway bridges are long-life assets that deteriorate with age, use and poor maintenance practices. The rail industry is suffering from ever-increasing maintenance costs which are exacerbated by increased rail traffic and reduced maintenance opportunities. In addition, bridge managers are expected to maintain their assets at specified performance levels while enduring budget cuts and resource constraints. There is an increasing demand for bulk material transport leading to increased axle loads pushing bridge structures to their design loading limit. Making informed decisions for cost-effective condition assessment, maintenance, repairs, upgrades and replacements, often with inadequate and sometimes inaccurate data is a major challenge in the management of railway bridges. Due to these challenges, infrastructure planners require additional time to plan and prepare maintenance budgets, analyse, interpret and make decisions for bridge asset life management. Many of the bridge management systems utilised in Australia are generic and analyse faults at the network level. In many cases, a detailed analysis of individual elements will provide a better understanding of root causes of faults and allow for more informed decision-making on bridge life enhancement. A practical framework for life cycle management of Australian concrete and steel railway bridges was developed in this research. This framework is based on life cycle cost analysis and consists of bridge assessment, maintenance optimisation and implementation. The outcome of this research is a faster, more accurate system that improves the informed decision-making capability for life cycle cost management of railway bridges.

Dynamically controlling exterior and interior window coverings through IoT for environmental friendly smart homes

Energy saving using smart home is of paramount importance to reduce heating and cooling energy consumption, and promote sustainable environment. Awnings and blinds have exhibited their effectiveness to reduce heating gain in summer and cooling loss in winter, respectively. Awnings are more effective to reduce heat gain in summer than blinds, while the opposite is true in winter. There exist many approaches in the current literature to remotely control flat curtains and blinds. However, up to our knowledge, no automatic technique is available in the literature, which can dynamically control the orientation of an exterior covering so that it can act like a blind in winter and an awning in summer. In this paper, we propose an automatic on-demand system to control the orientation and size of such exterior covering, and the turning air conditioners, heaters and lights on and off considering the rate of change of room temperature, and its lighting condition. We also discuss the properties and design of such exterior covering. A simulation model was developed to analysis the performance of our approach in terms of energy savings both in summer and winter.

Modelling risks to manufacturer and buyer for lifetime warranty policies

Abstract Currently, manufacturers/dealers have started selling products with lifetime warranty policies. In this paper, risk attitudes of both buyers and manufacturer/dealers to lifetime warranty policies are discussed. In line with Chun and Tang (1995) [2], Risk models are developed for products with time dependent failure intensity (rate). These models have been proposed with Non homogeneous Poisson’s process for failure intensity function, a constant repair cost, and concave utility function. Using the exponential utility function, the decision models are developed to maximise the manufacturer/dealer’s certainty profit equivalent. Risk preference models are developed to find the optimal warranty price through the use of the manufacturer’s utility function for profit and the buyer’s utility function for repair costs. Finally, the sensitivity of the warranty price models is analysed using numerical examples.

Development of integrated model for assessment of operational risks in rail track

Rail operating risks have been increasing due to increasing number of axle passes, steeper curves, wear-out of rails and wheels and inadequate rail-wheel grinding, poor lubrication and reduced maintenance. In 2000, the Hatfield accident in UK killed 4 people and injured 34 people and has lead to the cost of pound 733 million (AUDS 1.73 billion) for repairs and compensations. In 1977, the Granville train disaster in Australia killed 83 people and injured 213 people. These are related to rolling contact fatigue, wear and poor maintenance. This paper focuses on development of a conceptual integrated model for rail grinding, lubrication and inspection maintenance decisions. Risk based cost benefit model is developed for optimal inspection intervals.