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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Project ABSS : Adhesive bonding of stainless steels

Andersson, Viktor, Larsson, Andreas January 2017 (has links)
This report aims to increase the scientific knowledge about long-term prospects for the adhesive and adhesive joints for bonding of stainless steels. The effects of water, temperature and chemicals on the adhesive and adhesive joints are investigated. Stainless steel plates are pretreated with a primer and isopropanol, there after joined together with single lap modeling. The strength of the joint is tested with a tensile test and additionally a watertightness test is performed to determine if the joints are watertight. For this project three versions of stainless steels is used and two different technologies of two- part adhesives, silicone and silane-modified polymer and one technology of tape, a double coated acrylic foam tape are tested. The result shows that all the adhesives fails cohesively and that tape fails partly adhesively. Result shows that all tests are affected by water, temperature and chemicals on different levels but tape is affected the most with a minimum of 40% loss in shear strength. Watertightness test shows that aged tape joints are not watertight. The polymer shows no signs of decreasing in shear strength and is watertight, but does become more viscous by aging. The report shows that a possible combination of adhesive and pretreatment that can withstand the effects of water, temperature and chemicals is found. The polymer presents a possibility to bond stainless steel with a simple pretreatment. Tape didn’t pass the test in a suitable way but presents opportunities if a sufficient pretreatment can be found.
2

Assessing Moisture Resilience of Wall Assemblies to Wind-Driven Rain Loads Arising from Climate Change

Xiao, Zhe 18 February 2022 (has links)
Moisture loads arising from the deposition of wind-driven rain (WDR) on building façades can induce detrimental effects to wall assembly components and can adversely influence their long-term performance. Wind-driven rain as a climatic phenomenon will inevitably be affected by the evident changing climate in the near future. Wall assemblies subjected to wind-driven rain loads will also perform differently due to a varying moisture environment over the course of time. The performance of the building envelope, including the wall assembly, largely determines the serviceability of a building over its life cycle. Thus, it is essential for practitioners to understand and to be able to assess such performance. In this study, a complete procedure has been developed to permit assessing the moisture resilience of wall assemblies to wind-driven rain loads arising from climate change. The development of this procedure included four phases. In the first phase the historical and projected climate data was analysed to identify the possible wind-driven rain conditions to which a wall assembly may be exposed. The magnitudes of wind-driven rain and driving-rain-wind-pressure for different return periods were also investigated. Based on the results from phase one, a watertightness test protocol was established taking into consideration the possible ranges of wind-driven rain and driving-rain-wind-pressure as they may occur spatially, as well as temporally, across Canada. The range of watertightness test parameters was accommodated in the newly built Dynamic Wind and Wall Testing Facility (DWTF) at the National Research Council Canada. Thereafter in phase two of the research, wall assemblies having different configurations were tested in the DWTF following the test protocol to obtain the moisture load for wall assemblies under different wind-driven rain conditions. Such moisture loads were formulized and used in the third phase, where hygrothermal simulations were conducted to derive the hygrothermal parameters of the wall assemblies subjected to historical and projected climate data. In the final research development phase, different criteria and methods were explored to describe the performance of wall assemblies based on the hygrothermal parameters. During the development of the moisture resilience assessment procedure, a novel wind-driven-rain-pressure-index was devised to describe the extent of the effects arising from the concurrent action of wind-driven rain and driving-rain-wind-pressure loads on a vertical wall assembly; a new two-step approach was established to formulize the watertightness test results and thereby permit calculating the moisture load using values of hourly wind-driven-rain and hourly driving-rain-wind-pressure of a given location; a novel severity index was proposed to quantitatively describe the damage events arising from such moisture load on the wall assemblies. The moisture performance of tested wall assemblies subjected to historical and projected future climate were compared and discussed. The risks of occurrence of damage events in wall assemblies during different time periods were also demonstrated.

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