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Fibre metal laminates (FML) are the modern hybrid materials with potential wide range of applications in aerospace technology due to their excellent mechanical properties (particularly fatigue strength, resistance to impacts) and also excellent corrosion resistance. The study describes the resistance to low velocity impacts in Ti/CFRP laminates. Tested laminates were produced in autoclave process. The laminates were characterized in terms of their response to impacts in specified energy range (5J, 10J, 20J). The tests were performed in accordance with ASTM D7137 standard. The laminates were subjected to impacts by means of hemispherical impactor with diameter of 12,7 mm. The following values have been determined: impact force vs. time, maximum force and the force at which the material destruction process commences (Pi). It has been found that fibre titanium laminates are characterized by high resistance to impacts. This feature is associated with elasto-plastic properties of metal and high rigidity of epoxy - fibre composite. It has been observed that Ti/CFRP laminates are characterized by more instable force during impact in stage of stabilization of impactor-laminate system and stage of force growth that glass fibre laminates. It has been observed more stable force decrease in stage of stress relaxation and withdrawal of the impactor. In energy range under test, the laminates based on titanium with glass and carbon fibres reinforcement demonstrate similar and high resistance to low-velocity impact, measured by means of failure initiation force and impact maximum force.

The article discusses the impact of the TIG-micropulse welding parameters in the processing of low-thickness elements on the selected mechanical properties of joints in austenitic steel. The welding was semi-automatic to ensure distance of the electrode from the welded elements. It is concluded that the use of pulsation halves residual stress in thin elements.

Abstract: This work presents a numerical analysis of damage of composite materials with polymeric matrix reinforced with carbon fibres subject to static tension. Verification of numerical analyses was conducted with experimental methods – strength tests and microstructural observations. The methodologies applied were: the material damage modelling methodology based on XFEM (eXtended Finite Element Method) and contact interactions in a fibre–matrix connection layer using the CZM method (Cohesive Zone Method – Surface-based Cohesive Behaviour). ABAQUS/Standard software was the applied numerical tool. Microstructural analysis and numerical simulations indicate the fact that initiation of composite material damage takes place at the interface as a result of cracking and loss of fibre/matrix connection. This results in weakening of the composite microstructure in this area through the initiation of a reinforcement cracking process, which leads to further structural degradation, consisting in propagation of matrix cracking and, as a result, complete damage of the composite structure. The presented research of carbon/epoxy composite damage confirmed the adequacy of the prepared numerical model. [Copyright &y& Elsevier]