Infrastructure Engineering - Research Publications
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ItemNo Preview AvailableDeterministic failure prediction of toughened glass when impacted by ice(PERGAMON-ELSEVIER SCIENCE LTD, 2024-03)
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ItemLife-cycle performance of aluminium cladding panels in resisting hailstorms(Elsevier, 2024-05)This paper delves into cumulative damage on aluminium cladding panels attributed to hailstorms throughout the lifespan of the installations. 40 gas gun tests subjecting the cladding panel to repeated impact were undertaken for the purpose of studying cumulative damage behaviour. Insights from these tests were integrated into a hail size distribution model to characterise the probabilistic distribution of permanent indentation resulted from multiple hailstorm events. A life-cycle analysis framework was subsequently introduced, incorporating the natural variability of hailstone sizes and dynamic response of claddings to repeated ice impact. Intervention criterion can be established based on knowledge of the accumulation of permanent indentation into the cladding panels. Proactive actions are recommended should the indentations become visible to prevent worsening damage. Randomness of hailstorm occurrences was considered using hazard function which can be inferred from historical observations. Practical application of the proposed model is illustrated through case studies of two Australian states, coupled with comparative analyses highlighting key factors influencing cladding performance. The ability to account for stochasticity distinguishes the presented framework from existing deterministic approaches.
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ItemNo Preview AvailableFlexural strains in a toughened glass panel generated by impact of an ice sphere(PERGAMON-ELSEVIER SCIENCE LTD, 2023-10-01)
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ItemAn analytical approach for modelling contact forcing function of hailstone impact(Elsevier, 2023-03-24)The contact forcing function (of time) generated by the impact of hailstone is crucial to reliable predictions of damage to cladding and glazing panels. This article aims to present the development and validation of an analytical model for predicting this forcing function which is dependent on the size of the hailstone, its temperature, and velocity of impact. The development of this model was justified, as existing analytical models would only give accurate prediction of the peak contact force but not the time history. The newly developed forcing function is divided into two stages: Stage I (the loading phase) which is governed by the effective mass of the hailstone, and Stage II (the unloading phase) which is controlled by the gradual reduction in the stiffness of the disintegrating hailstone. The model has been calibrated against experimental results taken from eight impact tests which employed a modified Hopkinson bar for measurement of the contact force. The simulated predictions have also been validated by comparison against force time curves measured from another 11 impact tests which were independent from the ones employed for the model calibration.
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ItemIndentation modelling of aluminium cladding panels subjected to hailstone impact(Elsevier, 2023-09)In spite of colossal damage caused to aluminium panels in hailstorms, there is currently no rational design procedure found on research to regulate the design of building claddings or rooftops to withstand hail impact. Damage predictive models that have been reported in the literature are not suited to predicting hail induced damage. Thus, insurance premiums on damage to aluminium cladding caused by hail cannot be set to fairly distribute risks. In the current study, an analytical model for predicting permanent indentation generated by the impact of a hailstone is presented. The model was developed from a combination of plate theories and results from thirty-seven full scale impact experiments conducted on 900 mm ×900 mm aluminium panels. The model presented in this article takes into account strain rate effects and has been demonstrated to give predictions that are within some 10% difference from experimental measurements.
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ItemIndentation into an aluminium panel by the impact of a rigid spherical object(Elsevier BV, 2022-11)This paper introduces algebraic expressions for determining the amount of permanent indentation caused to an aluminium panel when impacted by a rigid spherical object. The magnitude of indentation is observed to vary significantly with the position of impact within the panel when the impactor and the velocity of impact are kept the same. This spatial variation of indentation is caused by the changes in the combinational mass (which is in turn function of the participating mass of the plate) and the Coefficient of Restitution COR. Both parameters are shown to correlate with the position of impact. The proposed algebraic expression featuring the combinational mass and COR as input parameters, allows potential damage to the panel to be predicted conveniently in day-to-day engineering practices. The original contribution of this article is in illustrating this phenomenon analytically, and have the analytical predictions verified by impact experimentation which has been conducted by the authors on panels of varying dimensions.
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ItemExperiments on an ice ball impacting onto a rigid target(PERGAMON-ELSEVIER SCIENCE LTD, 2022-09-01)This paper is concerned with the peak force (Fp) and time of occurrence (Tp) generated by the spherical ice specimen impacting onto a rigid target. The ice specimens had diameter ranging from 31.8 to 50.8 mm, and were prepared at temperature of -10°C and -30°C, respectively. The key original contribution of the article is the derivation of a correlation relationship for providing accurate predictions of Fp and Tp, for given hail size, velocity and temperature. A total of 149 Hopkinson bar tests were conducted, with impact velocity varying from 13 to 105 m/s for measuring the impact force. The tensile strength of ice, which is a term in the predictive expressions (and is measurable by the Brazilian tests), can be adjusted to take into account changes in temperature of the ice specimen. Experimental results showed that as the size of the ice specimen and its impact velocity increases, Fp increases significantly whereas Tp only increases slightly. Lowering of the temperature resulted in an increase in Fp, and decrease in Tp. Dimensional analysis was employed for processing the experimental data. Empirical relationships expressed as functions of impact velocity, specimen radius, tensile strength of ice, ice density and elastic wave speed of ice were derived. The ratio of the measured impulse to the momentum generated by the impact has also been checked, and was found to be within the range of 0.8 to 1.12. The derived empirical relationships will serve as a guide for further investigations into the structural responses to impact of an ice ball.