In response to serious environmental and economic concerns, the design and production of aircrafts have been changing profoundly over the past decades with the nose-to-tail switch from metallic materials to lightweight composite materials such as carbon fibre reinforced plastic (CFRP). In this context, the present doctoral research work aimed to contribute to the development of a CFRP booster casing, a real innovation in the field initiated and conducted by Safran Aero Boosters. More specifically, this thesis addresses the matter of joining metal/CFRP hybrid structures, which are prone to possibly detrimental residual stresses.The issue is treated with an approach combining experimental characterisation and finite element (FE) simulations. The multi-layered system’s state of damage was systematically examined on hundreds of micrographs, and the outcome of this study is presented under the form of a statistical analysis. Further, the defects’ 3D morphology is investigated by incremental polishing. A number of thermal and mechanical properties are measured by diverse physical tests on part of the constituent materials, i.e. the aerospace grade RTM6 epoxy resin, the structural Redux 322 epoxy film adhesive, and AISI 316L stainless steel. They are used as input data in a FE model of the multilayer that is developed and progressively refined to obtain detailed residual stress fields after thermal loading. These results are compared to experimental data acquired by X-ray diffraction stress analysis and with the curvature-based Stoney formula. Cohesive elements are placed at specific locations within the FE model to allow simulating progressive damage. Peel tests, mode I, mode II and mixed mode I/II fracture tests are thus performed in view of measuring the joint toughness. The results of these tests are discussed and the presence of residual stress in the fracture specimens is highlighted. Key information for the calibration of the cohesive law is finally identified via inverse FE analysis of the mode I test, this being a significant step in the process of building a damage predictive FE model of the multi-layered system. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

This thesis deals with the properties of soundproof partition structures in the low-frequency sound at impact sound insulation and security of acoustic comfort inside buildings. The prediction of impact sound is a simulation laboratory measurements of impact sound. The work is based on the occurrence of frequent complaints of inhabitants of residential homes for subjectively poor impact sound insulation of horizontal dividing structures, whose top layer is formed laminate. Although these structures conform in terms of impact sound insulation in accordance with the requirements of CSN 73 0532: 2010, residents complain about the subjective perception of the sounds of lower frequencies. A noise with a distinctive character of sound at low frequencies has been proved by measuring the spectral analysis and evaluation of sound pressure levels caused by the movement of persons roof construction to the floor. On the measurement and evaluation carried out in accordance with the measurement and evaluation of noise in non-working environment can be related requirement under the Regulation No. 272/2011 Coll. "On the protection of health from the adverse effects of noise and vibration." Occupational noise limits for protected buildings interior space do not apply to noise from ordinary use of the apartment. Under current legislation, the problem is in the Czech Republic at present insoluble. Therefore, this work explores ways evaluation of impact sound and delivery is determined conclusions. With the low-frequency impact sound insulation is also related to the latter part of this dissertation, where the computing program ANSYS (version 14.0) is simulated laboratory measurements of impact sound insulation of the real structure. The paper presents the results of simulation, and the sound pressure level in the receiving room to třetinooktávového band 630 Hz. These results are compared with measured values modeled in the laboratory.