PSI - Issue 72

Mohamed Khodjet Kesba et al. / Procedia Structural Integrity 72 (2025) 164–171

171

The increase of the operating temperature induces a more aggressive stress state which stresses the layers in a different way in terms of compression and tension, the change of the reference temperature is also a key parameter which shows the influence of the manufacturing parameters on the behavior of the laminate during the service, an increase of the stresses is noticed for a reference temperature lower than 180°C which is explained by the reduction in thermal stresses, so hygroscopic stresses will dominate the behavior. The change in operational humidity is a parameter that significantly drives the behavior of our laminate, the hygroscopic stresses generate a critical stress state compared to the thermal case, the stresses are more and more important depending on the moisture contamination in the laminate. The graphs show the central role played by the environmental parameters in the behavior of the composite laminate, considering the degradation shows a much more important implication where the stress is significantly increased following the fall of the mechanical performances induced by the temperature and humidity rate. 7. Conclusion The objective of this study is to examine the influence of environmental parameters and manufacturing parameters on the behavior of composite laminates during service, the peculiarity is the asymmetrical environment in which the laminate exist , the state of stress is controlled by the non-symmetrical state of the environment. The degradation of mechanical performance caused by temperature and humidity is also considered in this study, modeling of aging has been established according to a model taken at mico-analytic scale, which considers the effect of humidity and temperature. This allowed us to quantify the residual stresses during aging. Through the study, the residual stresses are quantified in accordance of operational temperature and humidity and also of the reference parameters, the residual stresses attained sometimes important values where the necessity to consider them during the dimensioning of composite structures, the degradation of composite amplifies the state of stress and makes it relate to a dangerous state. References Boukert, B.,Benkhedda, A., Adda, E.B., 2017, Hygrothermomechanic al behavior of thick composite plates using high order theory, Structural integrity Procedia 5, 115- 122, ISSN: 2452-3216 Boukert, B,., Benkhedda, A., Adda, E.B., 2018, Temperature and Humidity Influence Analysis on the Behavior of Thick Composite Plates Using High Order Theory, Structural integrity Procedia 13, 174-180, ISSN: 2452-3216 Boukert, B., Benkhedda, A., Adda, E.B., 2013, Analysis of Transient Hygrothermal Ageing Analysis of Hybrid Composite Materials in Asymmetric Environments, Key Engineering Materials 550, 49-56 Tounsi, A., Adda-Bedia, E.A., 2003, Simplified Method for Prediction of Transient Hygroscopic Stresses in Polymer Matrix Composites with Symmetric Environmental Conditions. In: Beaumont PWR, editor. International Journal of Applied Composite Materials 10(1). Kluwer academic publishers, 1 – 18 Tounsi, A., Adda-Bedia, E.A., Verchery, G. 2002, Influence of Anisotropy on the Transient Hygroscopic Stresses in Polymer Matrix Composites with Cyclic Environmental Conditions. In: Marshall IH, editor. International Journal of Composite Structures 55(4). London: Elsevier Applied Science, 393 – 405 Tounsi, A., Bouazza, M., Meftah, S.A., Adda-bedia E., 2005, On the Transient Hygroscopic Stresses in Polymer Matrix Laminated Composites Plates with Cyclic and Unsymmetric Environmental Conditions. Polym Polym Compos 13(5), 489 – 504 Benkeddad, A., Grediac, M., Vautrin, A, 1955, On the Transient Hygroscopic Stresses in Laminated Composite Plates. In: Marshall IH, editor. International Journal of Composite Structures 30(2). Elsevier Applied Science, 201 – 205 Hahn, H.T., Kim, R.Y., 1978, Swelling of Composite Laminates. Advanced Composite Materials-Environmental Effects, ASTM STP 658, 98 – 120 Sereir, Z., Adda bedia, E., Tounsi, A., 2006, Effect of Temperature on the Hygrothermal Behaviour of Unidirectional Laminated Plates with Asymmetrical Environmental Conditions. Int J Compos Struct. Compos Struct 72, 383 – 92 Sereir, Z., Adda bedia, E., Tounsi, A., 2005, Effect of the Accelerated Moisture Diffusivity on the Hygrothermal Behaviour of Laminated Plate with Symmetrical Environmental Conditions. J Thermal Stresses 28(9), 889 – 910 Sereir. Z., Adda bedia, E., Tounsi, A., 2005, Effect of the Accelerated Moisture Diffusivity on the Hygrothermal Behaviour of Laminated Plate with Symmetrical Environmental Conditions. J Thermal Stresses 28(9), 889 – 910 Springer, G., 1988, Environmental Effects. Section 16. In: Tsai SW, editor. Composites design. 4th ed. Dayton, OH 45419: Think Composites Tsai, S.W., 1988, Composite Design. 4th ed. Dayton: Think Composites Staab, G., 1999, Laminar Composite. London: Butterworth-Heinemann Boualem, Z., Sereir, Z., 2011, Accelerated Aging of Unidirectional Hybrid Composites Under the Long-term Elevated Temperature and Moisture Concentration, Theor. Appl. Fract. Mech. Chams, C.C., 1983, Simplified Composite Micromechanical Equations for Hygrothermal, an d Mechanical Properties”