He Xufei¹, Deng Zhongmin², Song Zhitao¹

Structural Durability & Health Monitoring, Vol.8, No.3, pp. 193-208, 2012, DOI:10.32604/sdhm.2012.008.193

Abstract This paper describes an information optimizing scheme which is developed by integrating rough set and hierarchical data fusion. The novel structural damage indices are extracted using the information from different sources and then imported into probabilistic neural network (PNN) for classification and health assessment. In order to enhance the accuracy of diagnosis, results from separate PNN classification are fused to achieve comprehensive decision. Rough set is employed to decrease the spatial dimension of data. The predictive accuracy of optimizing scheme is demonstrated on a helicopter, taken as an example, with varied sensors, for multiple damage More >

D. Crivelli¹, M. Guagliano², A. Monici³

Structural Durability & Health Monitoring, Vol.8, No.2, pp. 177-192, 2012, DOI:10.3970/sdhm.2012.008.177

Abstract Pultrusion is a process for manufacturing uniform section composite profiles, which allows to obtain structural elements of virtually any length. The use of E-glass fiber allows to obtain a material with a good rigidity-to-weight and strength-to-weight ratio; these features allowed to use these materials in civil structures, such as poles for anti-noise panels and public lighting, also thanks to their insulating properties. However, the knowledge on the damage development of these materials is still uncertain, and this is slowing down their development.
For these reasons, an experimental study on pultruded materials aimed at identifying the damage… More >

G. Pitarresi¹

Structural Durability & Health Monitoring, Vol.8, No.2, pp. 149-176, 2012, DOI:10.3970/sdhm.2012.008.149

Abstract The present work describes the implementation of active IR Thermography techniques for the NDT of thick polymer and glass-fibre reinforced polymer (GRP) composite panels. A low cost Thermal NDT set-up is proposed, comprising a single-detector IR camera with low thermal resolution and low frame rate, and common low-power halogen lamps as external heat source devices. The use of halogen lamps in particular requires several seconds of switch-on time in order to deliver meaningful and effective heat quantities. The influence of such long heat deposition intervals is investigated on the possibility to implement Transient Thermography and More >

G. Nicoletto¹, A. Saletti²

Structural Durability & Health Monitoring, Vol.8, No.2, pp. 131-148, 2012, DOI:10.3970/sdhm.2012.008.131

Abstract Fatigue strengthening of fillets by deep rolling is finding increased application for example in engine crankshaft production for functional and economical reasons. A fatigue design method aimed at exploiting the residual stresses that develop at a notched part following the rolling process is proposed. It is based on the superposition of residual stresses obtained by elastic-plastic FE simulation of the rolling process and the cyclic elastic stresses within a Haigh diagram framework. The fatigue design method is assessed using the experimental evidence obtained by testing notched specimens made of 30NiCrMo12 steel subjected to different rolling More >

G. Meneghetti¹

Structural Durability & Health Monitoring, Vol.8, No.2, pp. 111-130, 2012, DOI:10.3970/sdhm.2012.008.111

Abstract This paper deals with the local approach based on the Notch Stress Intensity Factors (NSIFs) to analyse the fatigue behavior of welded joints. In transverse load carrying fillet-welded joints, failure may occur either at the toe or at the root, depending on the geometry. At the toe, due to the flank angles that are usually encountered in practice, mode I local stresses are singular, while mode II stresses are not. Conversely, at the root of the particular joints analysed in the present paper both mode I and mode II stresses are singular and must be… More >

A. Risitano¹, D. Corallo¹, G. Risitano²

Structural Durability & Health Monitoring, Vol.8, No.2, pp. 91-110, 2012, DOI:10.3970/sdhm.2012.008.091

Abstract According to Miner's rule, the fatigue life of a material (or a mechanical component) is not a function of the order of the application of load. Many authors have already observed that the model proposed by Palmgren/Miner leads to underestimation of the damage and one of the reasons could be the disregard of the sequence of loads. Referring to the energy loss related to irreversible damage of the material, it was observed that the Miner's rule gives exact results only if the damage caused by the fatiguing load is low compared to the limit energy More >

G. Olmi¹

Structural Durability & Health Monitoring, Vol.8, No.1, pp. 61-90, 2012, DOI:10.3970/sdhm.2012.008.061

Abstract Turbogenerator rotors and coil retaining rings are highly loaded components, under low cycle fatigue at every machine switch on and switch off transient. Their failure during service may lead to very serious consequences. The present paper utilizes several experimental data, concerning the static, cyclic and fatigue behaviour of the rotor material, in order to perform a probabilistic analysis. All the main methodological issues are tackled, consisting in the experimental data processing, in the choice of the random variables that are involved in the fatigue process, in the determination of their distributions, in the practical computation More >

F. Curà¹, A. Gallinatti¹, R. Sesana¹

Structural Durability & Health Monitoring, Vol.8, No.1, pp. 45-60, 2012, DOI:10.3970/sdhm.2012.008.045

Abstract In this paper the effect of high cycle fatigue damaging on a commercial steel is investigated by means of experimental measurement of mechanical and dissipative parameters variation during fatigue testing. Experimental procedures for HCF damage incrementing on specimens and for parameter measurement have been defined. A statistical analysis of the significance of the results have been applied to select the parameters which best represent the damage progression on the specimen. More >

F. Berto¹, P. Lazzarin¹, D. Radaj²

Structural Durability & Health Monitoring, Vol.8, No.1, pp. 31-44, 2012, DOI:10.3970/sdhm.2012.008.031

Abstract The fictitious notch rounding concept is applied here for the first time to V-shaped notches with root hole subjected to in-plane shear loading. The fictitious notch radius ρ_f is determined as a function of the real notch radius ρ, the microstructural support length ρ* and the notch opening angle 2α, at first using the normal stress criterion in combination with the maximum tangential stress criterion for finding the crack propagation angle. An analytical method has been developed resulting in closed form expressions for the multiaxiality factor s in the well known relationship ρ_f=ρ+sρ*. It expresses the notch More >

F. Cianetti¹

Structural Durability & Health Monitoring, Vol.8, No.1, pp. 1-30, 2012, DOI:10.3970/sdhm.2012.008.001

Abstract This research activity refers to the problem of fatigue damage evaluation of mechanical components subjected to random loads. In detail, the present paper describes a procedure, developed by the author, that, starting from component modal modelling, can very quickly gives an answer to the request not only of a qualitative evaluation of its stress state but also of a quantitative and very reliable estimation of the component damage. This estimation is available (both in time and in frequency domain), regardless of the stress state recovery, only by an appropriate elaboration of lagrangian coordinates and elements stress More >