130 research outputs found
A validated modelling technique for incorporating residual stresses in glass structural design
No full textThis paper presents the development of a simple parabolic residual stress depth profile model for characterising residual stresses in construction-sector glass. The proposed model requires only the knowledge of the surface residual stress, which is usually available from glass manufacturers. Unlike the complex computational techniques reported in the literature, such as modelling physical, microstructural and mechanical phenomena of glass at different temperatures during manufacturing, the proposed model obviates the need for modelling multi-physics phenomenon of the generation of residual stresses. The proposed model also eliminates the need of sophisticated experimental equipment, such as Scattered-Light-Polariscopes (SCALP), which are usually not available among practicing engineers, in order to characterise the residual stresses. Residual stress predictions from the proposed parabolic model were validated against experimental results reported in the literature. Using the concept of eigenstrains, the paper also extends the results of the proposed parabolic residual stress depth profile model for incorporating the effects of residual stresses in stress analysis of glass structures
Environmental impact and embodied energy
No full textRecent reports from the industry suggest that FRP has been the most cost effective solution at “first installed” cost in a few recent structures. Even if the “first installed’ cost of FRP solutions in not favourable compared to equivalent concrete/steel structures the life cycle cost and life cycle assessment analyses could be used to demonstrate cost and sustainability benefits of FRP structures. For instance, FRP bridge decks have advantages, such as controlled off-site fabrication, high strength, highfatigue and corrosion resistance, light weight, easy transportation, faster on-site assembly, minimisation of traffic disturbances,etc.; these could be used to off-set the initial cost, and to exploit the sustainable solutions offered by FRP materials
Sustainability of glass in construction
No full textThis chapter discusses the potential applications of glass to deliver dynamic design solutions that enable buildings to be more energy efficient by making use of the most of daylight and solar gain whilst protecting the environment and conserving energy. The article also provides an overview of recent advances in modern glass products, and their potential applications in building envelops that can engineer reductions in the operational carbon. Glass is a brittle material, and its structural behaviour poses greater challenges when designing load-bearing structural members in buildings envelops. An overview of existing design guidelines of structural glass together with the need for detailed finite element analyses in accurate designs are briefly presented. The sustainability of glass as a construction material, including methods of recycle and reuse, is discussed. An outline of possible future developments in the use of glass in buildings is also presented
Data for figures in "Low cycle fatigue life prediction in shot-peened components of different geometries – Part II Life prediction"
No full textThis dataset reports data for the figures published in:
C. You, M. Achintha, K.A. Soady, P.A.S. Reed "Low cycle fatigue life prediction in shot-peened components of different geometries – Part II Life prediction"
The excel files included in this dataset were named in terms of the number of figures. Each excel file refers to a figure in the paper.</span
Dataset for: A Validated Modelling Technique for Incorporating Residual Stresses in Glass Structural Design. Structures Volume 29, February 2021, Pages 446-457
No full textData set for a journal manuscript: Mithila Achintha (2021) A validated modelling technique for incorporating residual stresses in glass structural design, Structures, Volume 29, Pages 446-457.
https://doi.org/10.1016/j.istruc.2020.11.052</span
Mechanical prestressing of annealed glass beams using pretensioned GFRP: characterisation and potentiality
No full textThis paper presents the results of an experimental investigation on the mechanical behaviour of annealed glass beams prestressed using adhesively-bonded pretensioned Glass Fibre Reinforced Polymer (GFRP) strips. The results show that the glass beams prestressed using pretensioned GFRP showed an increased load capacity compared to equivalent glass beams reinforced with unprestressed GFRPs. The prestressed glass beams showed a notable ductile post-cracked behaviour similar to annealed glass beams reinforced with unprestressed GFRP strips. The results also show that the proposed glass prestressing technique prevented premature debonding of the GFRP strips from the glass beams and explosive final failure of the glass beams, unlike in the mechanically-prestressed glass beams investigated in the literature where these failures were commonly observed
Data for figures in "Numerical modelling of the fatigue crack shape evolution in a shot-peened steam turbine material"
No full textThis dataset reports data for the figures published in:
C. You, B.Y. He, M. Achintha, P.A.S Reed "Numerical modelling of the fatigue crack shape evolution in a shot-peened steam turbine material" in the International Journal of Fatigue</span
Modelling residual stress in glass: Incorporation of the full stress field using a few stress measurements
No full textA comprehensive modelling technique for incorporating the effects of residual stresses (RS) in commercially available float glass (annealed glass and thermally-strengthened glass) is presented. RS are developed in glass due to the differential cooling experienced by glass during manufacturing (i.e. outer regions of glass cool and solidify first while the inner regions remain hot). Glass manufactures expect compressive surface RS of magnitude of ~80-150 MPa in thermally-strengthened glass. Surface compressive prestress enhances resistance against the development and propagation of surface cracks in thermally-strengthened glass. Although no RS are expected in annealed glass, research showed some RS in annealed glass, albeit of small magnitudes (usually <10 MPa). The effects of RS are critical for the structural performance and failure behaviour of glass structures. But, there is no accurate method to incorporate RS in stress analysis. Accurate stress analysis is required for design since glass is brittle and failures trigger at locations where high tensile stresses present. Therefore, the existing design practice of the ignorance of RS in annealed glass, and limiting the maximum design surface tensile stress determined from an analysis without incorporating RS to the surface RS specified by the manufactures of heat-strengthened glass usually result in structurally inefficient and cost expensive structures. Analysis of RS in glass by explicitly modelling differential cooling and the complex multi-physics process of glass manufacturing is virtually impossible, since the exact details of the thermal parameters and the viscous response of glass at different temperatures are unknowable. These parameters are difficult to be determined as they depend on complex phenomena, such as convection, radiation, thermal vibration and microstructural rearrangements. Rather than attempting to model the unknowable multiphysics phenomena of the generation of RS, we propose to model the RS distribution as the static elastic response of glass if a misfit strain (i.e. eigenstrains) representing the effects of all the mechanisms that contribute to the generation of RS in glass.Knowledge of a representative eigenstrains distribution in a given glass is a prerequisite in the proposed RS modelling technique. However, the representative eigenstrains distribution cannot be known at the beginning of an analysis and the determination of the eigenstarins is not trivial. We propose to determine a representative eigenstrains distribution by matching (in a least squares sense) the resultant RS distribution for an sensibly chosen initial assumed eigenstrains distribution with experimentally measured RS values at a finite number of locations. Finite element (FE)-based analyses are proposed for the stress analysis given the complex nature of the problem. In the present study, a scattered-light-polariscope (SCALP) was used to experimentally obtain RS values at a few selected locations in a given glass specimen. The recent advances in the SCALP techniques enable accurate measurements of RS in glass, in particular close to the surface regions. After an accurate estimate of the eigenstrain distribution has established, the full RS distribution in the glass specimen can be determined from a FE analysis by incorporating the estimated eigenstrains as a misfit strain distribution. The solution formulated this way satisfies equilibrium, compatibility, boundary conditions of the glass specimen, and the resultant RS distribution is entirely self-consistent. The step-by-step procedure of the proposed RS modelling technique is presented in Figure 1. Figure 2a shows the RS values measured at seven discrete points (up to 2 mm deep from the surface) of a 10 mm thick annealed glass specimen. The stress values were measured using a SCLAP with an accuracy of ±2MPa (as reported by the manufacture). Using the eigenstrains analysis described above, an estimate of the actual eigenstrains in the glass specimen was determined (Figure 2b). The estimated eigenstrains distribution was then incorporated in a 3D FE model to determine the full RS distribution. Figure 2c shows the full RS distribution in the middle region of the mid-plane (xz plane) of the glass specimen. Figure 2a also shows the comparison between the RS depth profile predicted from the eigenstrain analysis and the experimentally measured values. As can be seen from Figure 2a, the stresses predicted by the proposed model compared well with the measured values. Using the eigenstrains technique the RS distribution in thermally-strengthened glass were also determined. For example, Figure 3d shows the comparison between the predicted RS depth profiles in 10 mm thick annealed and fully-tempered glass. The eigenstrains technique of RS modelling was extended to analyse stress states in practical applications of glass structures, For example, Figure 3 shows the predicted RS distribution around a central hole (e.g. a hole drilled in glass for a bolted connection) in a fully-tempered glass piece. A 3D FE model was used in the analysis, and only a quarter of the specimen is modelled due to symmetry. The results showed a clear interaction between the geometry and the RS distribution. For example, RS distribution is not uniform over the internal surface of the hole, and this suggests the actual spatial distribution of RS must be taken into account in design in order to ensure structurally efficient, safe structures. The finding of this paper shows RS distributions in annealed and thermally-strengthened glass can be modelled using the knowledge of eigenstrain depth profile that may be determined from an inverse eigenstrain analysis using RS values measured at a few location of a given glass specimen. The paper also shows that the eigenstrain analysis can be implemented in FE models for accurate stress analysis of glass structures
Eigenstrain modelling of residual stresses generated by arrays of LSP shots
No full textThis paper presents an eigenstrain (misfit strain) model to predict the residual stresses (RS) generated by arrays of laser shock peening (LSP) shots (i.e. adjacent to each other over a surface patch or overlapping layers of LSP shots)where the use of a completely explicit analysis may be impractical.The results show that the LSP process parameters can be directly linked to the underlying eigenstrain distribution, which is shown to be approximately uniform over the area of the pulse and varies only with depth. Hence, the effect of multiple LSP shots at different locations can be rapidly assessed by superposition of eigenstrain distribution
A novel design concept for connections in glass: structural Integrity of glass reinforced with externally–bonded GFRP laminates
No full textThe paper reports experimental results of the load response and failure behaviour of open-hole annealed glass tensile test specimens reinforced with adhesively-bonded GFRP laminates. The results show that the bonded GFRP has potential to strengthen stress concentration features in glass by either arresting the cracks developed in the critical zone or eliminating the failure from the vicinity of the critical area. It is anticipated that the findings of this research could be effectively used to develop reinforcement strategies for critical joints in glass structures
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