Ashby, M & Jones, D (1996) Engineering Materials 1:An Introduction To Their Properties And Applications, Butterworth-Heinemann, pp. 169-178
Stratford, T. J. and Bisby, L. A., Effect of Warm Temperatures on Externally Bonded FRP Strengthening, J Compos.
Constr., 16, 235-244 2012.
D. Othman, T.J. Stratford and L.A. Bisby, 2013 “The Impact of Adhesive Conditioning upon Glass Transition Response”, Proceedings of the 6th International Advanced Composites in Construction (ACIC) Conference, Queen’s University Belfast, Belfast, UK, pp. 134-144.
G.M.H. Abed, M.M.K. Lee, 2013 “The Temperature Dependency of Adhesive Properties used in Bonding CFRP Plates to Civil Engineering Metallic Structures” ”, Proceedings of the 6th International Advanced Composites in Construction (ACIC) Conference, Queen’s University Belfast, Belfast, UK, pp. 125-133
M. D. Banea, F. S. M. de Sousa, L. F. M. da Silva, R. D. S. G. Campilho, A. M. de Bastos Pereira, 2011, Effects of Temperature and Loading Rate on the Mechanical Properties of a High Temperature Epoxy Adhesive, Journal of Adhesion Science and Technology, 25:18, 2461-2474
- Deformation generally assumed to be a function of stress. Creep deformations on the other hand are related to stress, time and temperature.
- Creep deformations become important at around 30% to 50% of the absolute melting temperature (in K).
- The textbook describes creep testing and states that it requires careful temperature control.
- Displacement is measure as a function of time which allows the plotting of the creep curve.
- Steady state creep for any material can be described by the creep equation using the experimentally obtained parameters.
Stratford, T. J. and Bisby, L. A., Effect of Warm Temperatures on Externally Bonded FRP Strengthening, J Compos.
Constr., 16, 235-244 2012.
- This paper uses experimental work to investigate the effects of warm temperatures on adhesive properties in a FRP strengthened steel beam.
- Initially the paper discusses the glass transition temperature of adhesive and the effect it has on the adhesive properties. It identifies that glass transition leads to a loss of strength and stiffness in the adhesive.
- The experimental testing involved a constant load being applied to the plate end of CFRP strengthened steel I beams and increasing the temperature to failure. During the tests digital imaging was used to observe the behaviour of the adhesive in terms of the slip deformation. All the beams tested at elevated temperatures failed by plate end debonding. It was also noted that until 40°C slip displacements were small but then increased in size until failure.
- The paper concludes that “warm temperatures can significantly reduce the strength of an FRP-plated steel beam.” It also identifies that the glass transition occurs over a range of temperatures. The need for research into the effect of temperature on the creep properties of the strengthening system is also noted.
D. Othman, T.J. Stratford and L.A. Bisby, 2013 “The Impact of Adhesive Conditioning upon Glass Transition Response”, Proceedings of the 6th International Advanced Composites in Construction (ACIC) Conference, Queen’s University Belfast, Belfast, UK, pp. 134-144.
- Focuses on how the curing conditions affect the glass transition response of an epoxy adhesive.
- The authors initially discuss what glass transition is and how important it is to the behaviour of an adhesive due to the resultant change in properties (strength and stiffness decrease but deformation capacity increases). They mention that the glass transition temperature is dependent on the degree of chemical cure and the physical aging of the adhesive. The authors then discuss the different test methods to determine the glass transition temperature of an adhesive.
- Tests were carried out by the authors using adhesive samples cured over a range of temperatures with half the samples cured under dry conditions and the other half cured under saturated conditions. Dynamic mechanical analysis was then carried out on the samples to determine the glass transition temperature under the different conditions. It was found that Tg was always lower for the saturated cured samples than the dry cured samples. It was also observed that the samples cured at ambient temperature had a significantly lower Tg than those cured at elevated temperatures.
- The authors also noted that the samples cured at ambient temperatures may never reach full cure as these samples did not show a significant enough improvement with age. Consequently it was concluded that “short-term tests on elevated temperature cured specimens cannot be used to predict the long-term performance of the on-site adhesive.”
G.M.H. Abed, M.M.K. Lee, 2013 “The Temperature Dependency of Adhesive Properties used in Bonding CFRP Plates to Civil Engineering Metallic Structures” ”, Proceedings of the 6th International Advanced Composites in Construction (ACIC) Conference, Queen’s University Belfast, Belfast, UK, pp. 125-133
- This paper investigates the effect temperature has on the mechanical properties of an epoxy adhesive using tensile tests on dog bone specimens.
- Initially it discusses the issues that can arise from temperature effects on a steel bridge strengthened using CFRP including loss of strength and stiffness and increased stresses in the adhesive layer due to steel and CFRP having different coefficients of thermal expansion.
- For the experimental tests, the specimens were cured at room temperature for seven days. Tensile testing was then carried out using an Instron machine. The results showed a reduction in tensile strength and modulus with increasing temperature. The authors of the paper also noted that the stress strain curve of the adhesive changes from linear to non-linear with increasing temperature and recommends the use of analytical or finite element analysis to investigate this.
- The paper then describes how pull off tests were used to examine the effect temperature has on the adhesive bond strength. It concludes that the bond strength decreases with increasing temperature.
M. D. Banea, F. S. M. de Sousa, L. F. M. da Silva, R. D. S. G. Campilho, A. M. de Bastos Pereira, 2011, Effects of Temperature and Loading Rate on the Mechanical Properties of a High Temperature Epoxy Adhesive, Journal of Adhesion Science and Technology, 25:18, 2461-2474
- In this paper the authors study the combined effects of loading rate and temperature on the tensile properties of an epoxy adhesive cured at a high temperature.
- Firstly the authors noted that the major influences on the strength of an adhesive joint are the cure shrinkage, the coefficient of thermal expansion and the change in adhesive mechanical properties with temperature. They also state that previous individual studies showed that a reduction in yield stress and modulus with increasing temperature and that increasing the loading rate increases the yield stress.
- Their experiments involved tensile testing of an epoxy adhesive cured at 140°C. using three loading rates (0.1, 1 and 10 mm/min) and four temperatures (room, 100, 125 and 150°C). The authors found that the ultimate tensile stress and young’s modulus of the specimens reduced when tested at higher temperatures. However, the specimen at each temperature with the highest loading rate had the greatest ultimate tensile strength and modulus implying that they increase with faster loading rates.
- The authors also identified that there was an increase in deformation capacity with increasing temperature suggesting that the failure strain increases with temperature. They also found that the rate of reduction of the ultimate tensile stress increased at the temperatures closer to the glass transition temperature which highlighted the significance of the effect glass transition has on the strength of an adhesive. It was also concluded that the loading rate has a greater effect on the ultimate stress and modulus at lower temperatures away from the glass transition temperature.