The usage of metal Additive Manufactured (AM) components is growing in aerospace industry since the establishment of quality standards and due to the current maturity of the manufacturing systems, processing route, and inspection methodology. Moreover, possibilities of designing complex shapes by using 3D-printers enables design engineers to build lightweight structures and/or increase part functionality. However, the freedom in design is often a challenge for non-destructive testing (NDT), especially in parts with limited access, non-flat surfaces, etc. Therefore, there are few NDT methods which can be applied on such complex 3D geometries and capable of inspecting the whole part volume. Computed Tomography (CT) and Digital Xray methods are the most relevant ones offering rich information of inner defectology and the outer geometrical metrology. Simulation tools regarding manufacturing process and mechanical behavior are already considered as part of the definition phase of AM components and utilized as inputs in the design loop. However, inspectionability issues are mainly considered during the quality assurance phase. Therefore, inspection problems related with the detectability of defects above the part allowable can appear once the part have been designed, validated, and manufactured. On the other hand, tools that perform numerical simulations of X-ray imaging like SimCT could be a valuable source of additional information [1]. Firstly, for the users of XRay imaging devices in order to set up best inspection parameters and system configuration [2, 3]. Secondly, for producing CT simulations which can evaluate the inspectionability of a part, avoiding non-inspectionable regions limited by the inspection method. In this way, this information can be introduced for validating the part design for instance at PDR (Preliminary Design Review) and later at CDR (Critical Design Review) levels. In this work, an aluminum Image Quality Indicator (IQI) with calibrated defects has been analyzed with both real and simulated CT scans using different physical resolutions. In this way, a comprensive analysis for determining the limits of defect detectability by comparing both simultaion and test results has been developed. Defects of 100, 200 and 500µm diameter have been evaluated, corresponding to aerospace allowable for pores in AM hardware, depending on part criticality.

Europe is facing one of the most challenging decades with the decarbonization of the energy generation. The increase in the use of energy from renewable sources is essential for the climate and energy global goals. In this way, the optimization of maintenance and repair works of the involved production systems is necessary to reduce costs and time of operation, especially in wind farms, where accessibility is reduced and usually dangerous. For this reason, novel technologies and applications are being investigated in the O&M field like the use of unmanned aerial vehicles (UAVs) for structural assessment of wind blade components through non-destructive technologies (NDT). This is the main goal of DURABLE project, where this investigation is framed. This work is focused on the comparative analysis of different ultrasonic technologies and the development of a protocol for the inspections of wind blades for its application by means of aerial vehicles. The inspections tests have been conducted on samples at laboratory level as a previous work for the post implementation of this technology with drones in field. Diverse UT transducers with 4.0 to 5.0 MHz emission frequencies as well as single element and phased array probes have been used to determine the best configuration for the inspection of each material and thickness of wind blades. To characterize the detectability, artificial defects (impacts and flat-bottomed drills) have been introduced in the test samples to analyze the detectability with manual handled UT inspections. Finally, the most suitable ultrasonic probe was selected, adapted and integrated in an end effector for its implementation in a UAV. The applicability of the inspection by using aerial vehicles has been tested in relevant environment (at laboratory) and in real windfarm.

Nowadays, the ultrasonic inspection (UT) is the most common non destructive technique (NDT) for composite components in the aerospace industry, due to its high accuracy, reliability and the degree of industrialization. Although UT is widely developed, new manufacturing processes and part concepts are continuously pushing the technology for new improvements and applications. This is the case of the geometries resulting from novel out of autoclave composites manufacturing technologies, Liquid Resin Infusion (LRI) or Resin Transfer Moulding (RTM), allow the fabrication of parts in one shoot, with focus in bringing answers to the challenge of manufacturing fully assembled parts and avoiding secondary assembly phases but also limiting the accessibility for NDT inspections. In this sense, one of the critical issues in the aeronautic sector is the improvement of the inspection of geometries with difficult access and small dimensions. The requirement of the aeronautic industry of guaranteeing the quality of the primary composite structures implies the inspection of the whole component through certified technologies. This constraint, together with the lack of technological solutions for the inspection of regions with limited accessibility is blocking the industrial implementation of optimized manufacturing processes. The present work describes the design and development of adaptive hardware solutions for the single and phased array UT inspection of internal structures on a highly integrated composite aeronautic component. The final solution has been obtained as result of an iterative design process and manufactured through additive manufacturing technology (Powder Bed Laser Fusion, formerly Selective Laser Sintering) using polyamide. This device was validated in a for inspection of flat surfaces of stiffener internal structure, belonging to the composite flap demonstrators of lengths: 3 meters in a first approach, and 8 m for final validation. This novel inspection solution has been performed in the framework of the FLAP project to develop and innovate the manufacturing process for complex mobile surfaces in a collaboration between Aernnova, through its Composites Division, and CATEC teams.