Residual Strength Research Papers - Academia.edu (original) (raw)

This paper presents a methodology for predicting the thresholds of multiple site damage and widespread fatigue damage in fuselage lap slices. Widespread fatigue damage is a type of multiple cracking that reduces the airframe residual... more

This paper presents a methodology for predicting the thresholds of multiple site damage and widespread fatigue damage in fuselage lap slices. Widespread fatigue damage is a type of multiple cracking that reduces the airframe residual strength to a level below the damage tolerant requirement. The MSD threshold refers to the point in the lifetime of an airplane when two adjacent

The use of functional repair components stored inside hollow reinforcing fibres is being considered as a self- repair system for future composite structures. This paper considers the problem of introducing a liquid healing resin,... more

The use of functional repair components stored inside hollow reinforcing fibres is being considered as a self- repair system for future composite structures. This paper considers the problem of introducing a liquid healing resin, contained within hollow glass storage vessels, within a space environment. The problem of resin outgassing of a commercially available 2-part epoxy resin system and the thermal cycling of the glass storage vessels, and their sealing caps, are discussed. The mechanical property assessment of the baseline hollow fibre laminate, the damaged hollow fibre laminate and the healed hollow fibre laminate is discussed revealed that a self-healed laminate had a residual strength of 87% compared to an undamaged baseline laminate and 100% compared to an undamaged self-healing laminate. This study provides clear evidence that a FRP laminate containing hollow fibre layers can successfully self-heal.

The aim of this paper is to assess the performance of self-compacting glass concrete (SCGC) after exposure to four elevated temperatures of 300 °C, 500 °C, 600 °C and 800 °C. The influence of curing conditions on the high temperature... more

The aim of this paper is to assess the performance of self-compacting glass concrete (SCGC) after exposure to four elevated temperatures of 300 °C, 500 °C, 600 °C and 800 °C. The influence of curing conditions on the high temperature performance of SCGC was also investigated. For each curing regime, five SCGC mixtures were prepared with recycled glass (RG) which was used to replace natural fine aggregate at the level of 0%, 25%, 50%, 75% and 100%. After exposure to the elevated temperatures, concrete mass loss, density, water porosity, ultrasonic pulse velocity (UPV) and water sorptivity were determined and then a compressive strength test was conducted. The test results indicate that regardless of the exposure temperature, all the water cured specimens had higher residual strengths and mass losses while the water porosity and water sorptivity values were lower as compared to the corresponding air cured specimens. The incorporation of RG in the concrete mixes helped to maintain the concrete properties after the high temperature exposure due to the melting and resolidification of the recycled glass in the concrete matrix.

Fibre-reinforced plastics (FRP) are susceptible to damage resulting from impacts, even non-penetrating ones. This damage, even without outright destruction, may lead to reduction of fibre-reinforced plastics strength and static... more

Fibre-reinforced plastics (FRP) are susceptible to damage resulting from impacts, even non-penetrating ones. This damage, even without outright destruction, may lead to reduction of fibre-reinforced plastics strength and static load-bearing abilities. This paper presents the results of three-point flexural tests on glass fibre/polyester composites after non-penetrating ballistic impact, where the word “ballistic” refers to a high-speed free-flying impactor (projectile). This is a continuation of previous studies, during which the extent of damage in glass/polyester composites after non-penetrating ballistic impact was evaluated. Materials used in the study were laminated composites produced via the Resin Transfer Moulding (RTM) technology. This laminates were produced using Polimal 1094 AWTP-1 unsaturated polyester resin and E-glass reinforcement in the form of multiple perpendicular layers of chopped-strand mats, continuous-filament mats, twisted-yarn fabrics and woven rovings. Composites with varying thickness, number of layers and fibre content were produced. The impactor is a free-flying 3 g steel ball propelled from a gas gun. Two striking velocities were tested - 60 and 70 m/s, producing impact energies of 5.4 and 7.35 J accordingly. After the impact, the extent of damage in samples (100x100 mm square plates) was evaluated through digital image analysis. The as-impacted samples were then subjected to three-point bending under set conditions. The results were compared to the results of identical examination of undamaged samples and the reduction in mechanical properties was determined. In all cases, the reduction in strength and load-at-break value was noticed. Thicker, more reinforced laminates show lower loss of mechanical properties, than thinner ones. Difference between strength and load-at-break approach for load-bearing abilities reduction was discussed, and the conclusion is that the latter is preferred to the former in laminated composites due to high thickness dependence of strength. Comparing reinforcement types, continuous-filament mat is superior to chopped-strand mat and woven-rovings. Tightly woven twisted-yarn fabric compares favourably to the woven rovings.

Geopolymer concrete can be expressed as "concrete without cement". Geopolymer concrete is environmentally friendly and an inventive way to replace the conservative concrete which contributes 7-8% of total CO2 production in the world. "The... more

Geopolymer concrete can be expressed as "concrete without cement". Geopolymer concrete is environmentally friendly and an inventive way to replace the conservative concrete which contributes 7-8% of total CO2 production in the world. "The concrete which entails of the source materials and the alkaline solution". The source material can be from agricultural wastes such as Bagasse ash, Rice husk ash, Palm fuel ash, etc and the industrial by-products such as Fly ash, Ground Granulated Blast Furnace Slag, Copper Slag, etc. The alkaline solutions can be either sodium hydroxide and sodium silicate or potassium hydroxide and potassium silicate. In the present study, an effort has been made to check the likelihood of reuse of bagasse ash in Geopolymer Concrete by probing mechanical properties of M30 grade concrete for 0, 25, 50, 75 and 100 percent replacement by bagasse ash. The behavior of 100% GGBS replaced concrete under elevated temperature by weight loss, residual strength, cracking pattern and spalling pattern.

The primary aim of the present study is to investigate the collision resistance and residual strength of single side skin (SSS) and double side skin (DSS) bulk carriers subject to collision damage. The impact dynamics analyses were... more

The primary aim of the present study is to investigate the collision resistance and residual strength of single side skin (SSS) and double side skin (DSS) bulk carriers subject to collision damage. The impact dynamics analyses were conducted using ANSYS LS-DYNA for the evaluation resistance forces, energy absorption and penetration depth for various collision scenarios. The struck vessels of Capsize SSS and DSS designs were assumed to be entirely standstill and the striking vessels of an Aframax-type oil tanker with different bulbous bow shapes were modeled as rigid bodies. The findings were compared, where possible, with existing analytical tools. Residual strength calculations on SSS and DSS vessels were computed corresponding to all considered collision damage scenarios. Traditional Smith's method was applied with the average stress — average strain relationships of elements based on derived semi - analytically. The effect of corrosion was also evaluated by Joint Bulker Project (JBP) Rules on the influence of plate and stiffener thickness. The safety of the vessels was determined as a ratio of the ultimate hull girder strength to bending moment in damaged condition. Finally, results and insights derived from the present work are summarized.

The objectives of this research were to provide the Illinois Department of Transportation (IDOT) with an ultrathin whitetopping (UTW) thickness design method and guidelines for UTW design, concrete material selection, and construction... more

The objectives of this research were to provide the Illinois Department of Transportation (IDOT) with an ultrathin whitetopping (UTW) thickness design method and guidelines for UTW design, concrete material selection, and construction practices. A new mechanistic-empirical design method was proposed based on a modified version of the American Concrete Pavement Association (ACPA) design method for UTW. This proposed guide calculates the required UTW thickness based on traffic level, pavement layer geometry, climate, materials, and the pre-existing hot mix asphalt (HMA) condition. Laboratory testing of UTW concrete mixtures suggested many proportions and constituents can be successfully used as long as consideration is made to minimize the concrete’s drying shrinkage (e.g., limited cement content) and maintain the concrete-HMA bond. The laboratory testing coupled with previous fiber-reinforced concrete (FRC) slab tests suggested that structural fibers should be utilized in future UTW ...

Methods have been developed to describe the fatigue initiation and propagation mechanisms in flat panels as well as mechanically fastened joints and to determine the residual strength of large flat panels. Glare shows excellent crack... more

Methods have been developed to describe the fatigue initiation and propagation mechanisms in flat panels as well as mechanically fastened joints and to determine the residual strength of large flat panels. Glare shows excellent crack growth characteristics due to the mechanism of delamination and fibre bridging. The fatigue insensitive fibres restrain the crack opening and transfer load over the crack in the metal layers. During the initiation phase fibre bridging does not occur and the behaviour is dominated by the metal initiation properties. Mechanically fastened joints introduce additional effects such as secondary bending, load transfer and aspects related to the fastener installation. The residual strength of Glare is dependent on the amount of broken fibres and the delamination size and can be described with the R-curve approach. The impact resistance of Glare is related to the aluminium and glass/epoxy properties and is significantly higher than the impact resistance of mono...

Adhesive bonding technology has played an essential role in the development and growth of the rehabilitation and repair of timber structures. The ability of a structural joint to maintain satisfactory long-term performance, often in... more

Adhesive bonding technology has played an essential role in the development and growth of the rehabilitation and repair of timber structures. The ability of a structural joint to maintain satisfactory long-term performance, often in severe environments, is an important requirement of a ...

A round robin test programme was carried out on the beam-bending test recommended by the RILEM TC 162-TDF [1]. Plain concrete and steel fibre reinforced concrete (SFRC) beams were included in the test programme. The material variables for... more

A round robin test programme was carried out on the beam-bending test recommended by the RILEM TC 162-TDF [1]. Plain concrete and steel fibre reinforced concrete (SFRC) beams were included in the test programme. The material variables for the SFRC beams consisted of two concrete strengths, three fibre dosages and three types of fibres. A comprehensive statistical analysis was carried out to determine the applicability and robustness of the test method. It was found that although inter-lab variations do occur, this was relatively small compared to the inherent material variation. It is also possible that the high variations observed could be due to the relatively small cross sections used for the test beams. Additionally, an investigation was carried out to evaluate the objectiveness of the calculation procedure proposed by RILEM TC 162-TDF to obtain the necessary design parameters. It was found that the prescribed calculation procedure was satisfactory, as the variation between the design parameters calculated at different laboratories was generally within the range of ±5%. An alternative method of obtaining the design parameters, by considering residual strengths, is suggested as it simplifies the calculation procedure and the test method. In general, the beam test was found to be a good robust test and relatively easy to carry out. Un programme d'essais comparatifs entre laboratoires a été réalisé pour le test de poutre soumise à la flexion, comme prescrit par TC 162-TDF de la RILEM. Des poutres en béton normal et en béton de fibres métalliques (BFM) sont inclues dans le programme d'essais. Pour les poutres en BFM, on a considéré comme variables de matériaux: deux résistances à la compression, trois dosages de fibres et trois types de fibres. Une analyse statistique exhaustive a été exécutée pour déterminer la pertinence et la solidité de la méthode d'essai. On a constaté que, bien que des variations de résultats entre les laboratoires existent, celles-ci sont relativement petites, surtout lorsque l'on compare avec les variations intrinsèques des matériaux eux-mêmes. Ces dernières variations peuvent être également dues aux sections transversales relativement petites qui sont utilisées pour les essais de poutre. Ensuite, une analyse a été réalisée en vu d'évaluer l'objectivité de la méthode de calcul qui est proposé par TC 162-TDF de la RILEM pour obtenir les paramètres nécessaires lors du dimensionnement. On a constaté que le méthode de calcul prescrite était satisfaisante, parce que la variation des paramètres, calculée par les différents laboratoires pour le dimensionnement, était d'un ordre de grandeur de ±5%. Une méthode alternative est néanmoins proposée pour obtenir les paramètres de dimensionnement en prenant en considération la résistance résiduelle. Cette méthode simplifie la méthode de calcul et la méthode d'essai. En général, l'essai de poutre soumise à la flexion simple, comme prescrit par le TC 162-TDF de la RILEM, est un essai robuste et relativement simple à exécuter.

In the present work OPC and OPC/slag concretes were exposed to elevated temperatures, 400 and 800°C. The critical temperature of 400°C has been reported for OPC paste. Above 400°C, the paste hydrate Ca(OH)2 dehydrates into CaO causing the... more

In the present work OPC and OPC/slag concretes were exposed to elevated temperatures, 400 and 800°C. The critical temperature of 400°C has been reported for OPC paste. Above 400°C, the paste hydrate Ca(OH)2 dehydrates into CaO causing the OPC paste to shrink and crack. After cooling and in the presence of air moisture, CaO rehydrates into Ca(OH)2, resulting in disintegration