Comparative analysis of internal and external-hex crown connection systems - a finite element study

The abutment connection with the crown is fundamental to the structural stability of the implant system and to the prevention of mechanical exertion that can compromise the success of the implant treatment. The aim of this study is to clarify the difference in the stress distribution patterns between implants with internal and external-hex connections with the crown using the Finite Element Method (FEM). Material and Methods: The internal and external-hex connections of the Neoss and 3i implant systems respectively, are considered. The geometrical properties of the implant systems are modeled using three-dimensional (3D) brick elements. Loading conditions include a masticatory force of 200, 500 and 1000N applied to the occlusal surface of the crown along with an abutment screw torque of 110, 320 and 550Nmm. The von Mises stress distributions in the crown are examined for all loading conditions. Assumptions made in the modeling include: 1. half of the implant system is modeled and symmetrical boundary conditions applied; 2. temperature sensitive elements are used to replicate the torque within the abutment screw. Results: The connection type strongly influences the resulting stress characteristics within the crown. The magnitude of stress produced by the internal-hex implant system is generally lower than that of the external-hex system. The internal-hex system held an advantage by including the use of an abutment between the abutment screw and the crown. Conclusions: The geometrical design of the external-hex system tends to induce stress concentrations in the crown at a distance of 2.89mm from the apex. At this location the torque applied to the abutment screw also affects the stresses, so that the compressive stresses on the right hand side of the crown are increased. The internal-hex system has reduced stress concentrations in the crown. However, because the torque is transferred through the abutment screw to the abutment contact, changing the torque has greater effect on this hex system than the masticatory force. Overall the masticatory force is more influential on the stress within the crown for the external-hex system and the torque is more influential on the internal-hex system.Griffith Sciences, Griffith School of EngineeringFull Tex

Mechanical characteristics and durability of HMA made of recycled aggregates

The application of recycled aggregates in the asphalt industry has been investigated in recent decades. However, low percentages of these materials have practically been used in asphalt mixtures because of the limitations set by the relevant specifications due to their performance uncertainties. This research investigates the feasibility of increasing the percentage of recycled aggregates to 100% in hot mix asphalt (HMA). Recycled concrete aggregate (RCA), recycled glass (RG), and reclaimed asphalt pavement (RAP) were used to develop HMAs suitable for roads with light to medium traffic. First, potential mix designs were proposed using an innovative approach considering the industry’s needs. Next, the volumetric properties, tensile strength, moisture sensitivity and resilient modulus response of the mixtures under different temperature conditions were determined and compared. In general, the proposed recycled material HMA exhibited superior mechanical and resilient modulus performances, i.e., 45 to 145% increase in stiffness, and up to 99% higher in Marshall stability. Furthermore, higher tensile strength ratios of the recycled material mixtures indicated a greater resistance to water damage, and hence greater durability. The findings of this research provide evidence-based insights into the increased proportion of recycled materials in the construction of asphalt pavements, thereby promoting sustainable pavement construction materials

Prediction of residential slab foundation movement through a finite element-based deep learning algorithm

Deep learning networks were employed to predict the maximum differential deflection of stiffened and waffle rafts due to reactive soil movements, Δmax. Four deep learning networks were used to predict Δmax, these are (1) stiffened rafts on shrinking soil, (2) stiffened rafts on swelling soil, (3) waffle rafts on shrinking soil, and (4) waffle rafts on swelling soil. The deep learning models were used to create design lines, which showed that both soil and structural features strongly influence the stiffened rafts. In contrast, waffle rafts showed a strong dependence on soil features in shrinking soils and beam depth in swelling soils. This demonstrates that the finite element-based deep learning networks captured the effect of the embedment of the beams. The results of the deep learning models led to non-linear design curves, which are disparate from the suggested standard Australian design. These results suggest that increasing the value of beam depth can have a positive or negative impact on the global residential slab depending on the type of substructure and whether the founding reactive soil is shrinking or swelling. Global sensitivity analyses of the deep learning models showed that for stiffened rafts on shrinking soil, the slab length, slab width and active depth zone of reactive soil had the most significant influence on Δmax, whilst for stiffened rafts on swelling soil, the primary drivers are ground movement, beam depth, and slab width. The prediction of Δmax for waffle rafts on shrinking soil was driven by the surface characteristic and mound movements, and the active depth zone, whilst waffle rafts on swelling soil was driven by the beam depth. Overall, the finite element-based deep learning showed the capacity to estimate Δmax in both shrinking and swelling design scenarios for different types of residential footing systems to further understand the characteristic behaviour of shallow residential slab foundations on reactive soils leading to improved designs

Application of software and hardware-based technologies in leaks and burst detection in water pipe networks: a literature review

With the rise of smart water cities, water resource management has become increasingly important. The increase in the use of intelligent leak detection technologies in the water, gas, oil, and chemical industries has led to a significant improvement in safety, customer, and environmental results, and management costs. The aim of this review article is to provide a comprehensive overview of the application of software and hardware-based technologies in leak detection and bursts in water pipeline networks. This review aims to investigate the existing literature on the subject and to analyse the key leak detection systems in the water industry. The novelty of this review is the comprehensive analysis of the literature on software and hardware-based technologies for leak and burst detection in water pipe networks. Overall, this review article contributes to understanding the latest developments and challenges in the application of software- and hardware-based technologies for leak and burst detection in water pipe networks, and serves as a valuable resource for researchers, engineers, and practitioners working in the field of water distribution systems

Mechanical and physical properties and cyclic swell-shrink behaviour of expansive clay improved by recycled glass

The stabilisation of expansive clay subgrades using recycled glass (RG) was proposed, as a sustainable ground improvement technique. Previous studies mainly focused on using RG powder with contents up to 10%, while the current study utilised sand-size particles and up to 40% RG content. Physical properties, compressibility, strength characteristics, and long-term climatic effects on the volumetric behaviour of stabilised clay were investigated. Volumetric responses of stabilised clay were analysed through a constitutive model developed for environmentally stabilised clay. The experimental results revealed that the plasticity of mixtures decreased by 30% as RG content increased to 40%. By using larger RG particles, the strength and bearing capacity increased by about 45% and 130% with the addition of 25% RG. However, adding about 6% of glass powder was sufficient to increase the strength and bearing capacity to about 100% and 200%, respectively. The swell-shrink results suggested that the maximum swelling was achieved in the second cycle in which the clay classification was converted from medium to high expansive clay. The experimental results were also compared and discussed with corresponding data collected from the literature. The outcomes of this study advance the prediction and understanding of the mechanical behaviour of RG-stabilised clay

Environmental, economic, and serviceability attributes of residential foundation slabs: a comparison between waffle and stiffened rafts using multi-output deep learning

The design of residential foundation slabs is commonly based on standards that emphasise the structural aspects and safety of the structure. Factors related to environmental and economic criteria are seldom given due consideration in the design phase. Considering the growing demand for sustainable approaches driven mainly by climate change concerns, this study developed a smart tool called Multi-OUtput Non-linear Design of Slabs (MOUNDS), which simultaneously predicts embodied energy, carbon emission, life cycle cost and deflection of waffle and stiffened rafts. MOUNDS considers the environmental, economic, and serviceability criteria of waffle and stiffened rafts on soils having varying reactivities. The standard deemed-to-comply design code for residential slabs and footings in Australia was investigated to determine the most advantageous foundation type in terms of both sustainability attributes and serviceability performances. The developed MOUNDS algorithm has shown accurate predictions. The predicted values of the: embodied energy of the residential slabs, greenhouse gas emission of the residential slabs, life cycle cost of the residential slabs, and maximum deflection of the residential slabs of waffle rafts were found more sustainable and serviceable than stiffened rafts in slight to moderate reactive sites. When sites are highly reactive, the difference between the environmental and economic of waffle rafts and stiffened rafts was minimal and did not conform to the serviceability limits of the Australian design code. This novel study linked and predicted the multi-disciplinary relationship between the environmental, economic and structural design aspects of residential slabs through machine learning. This is valuable in decision-making throughout the design phase considering the multi-faceted aspects of residential footing systems on reactive soils

Full-depth flexible pavement performance impacted by rainfall: Finite element analysis

[[notice]]補正完