This paper presents a modelling study of a ball bearing dynamic behaviour with differentdefects types, which is part of an investigation related to the modelling of machineryrotating components. Our contribution in this work is a proposition of a five-degree offreedom model describing the nonlinear dynamic behaviour of a ball bearing. The aim is aparametric formulation of the ball bearing stiffness which allows the introduction of thedefects characteristics. This approach is a result of an intrinsic structural behaviourmaking it different from methods which introduce external impulsion to simulate defects.Hence, a more realistic dynamic ball bearing defect simulation is obtained for better usein design and maintenance domain. This simulation can be formulated by two methods. Thefirst, partial contact method, is based on elimination of some ball stiffness. The secondone imposes displacement in the system response. Obtained results give response formssimilar to standards and to different author’s results (theoretical and experimental)found in the literature. The developed model is simple, compact as compared to existingones and we can express our satisfaction about this promising model.

Any approach which aims to improve the quality and safety of eggs, is of limited value unless it can relate to the incidence of breakages in the field, and can be applied either directly to breeding programmes or used as online tools for quality assurance. Online systems require the method of assessment to be non-destructive. This is probably not so important for breeding companies who tend to gauge the usefulness of an eggshell quality measurement by its ease of measurement, its heritability and, its genetic correlation with other phenotypic traits. Historically, qualitative measures such as shell breaking or puncture strength, non-destructive deformation and specific gravity have been widely adopted as tools in selection programmes. The dynamic stiffness is a novel eggshell quality measurement, which could be utilised by poultry breeders as it has a moderate heritability and high genetic and phenotypic correlation with other shell quality traits including eggshell breaking strength. This non-destructive measurement could also be applied on-line to monitor shell quality. An alternative approach is to use genetic markers as tools to aid conventional breeding programmes where an important eggshell quality trait is practically too difficult or expensive to fully exploit. Marker-assisted selection for the genes coding for organic matrix proteins may provide a way of incorporating other beneficial egg quality traits into selection programmes in the future.