DSpace Repository

Welcome to the NLR Reports Repository

Royal NLR conducts research, which is published in reports. Only a minor part of these reports is made public. This repository holds these public, so called Technical Publications (TP), mainly produced from 1996 up till now.

Technical publications published before 1996 may be obtained using the request-form. Other types of NLR-reports are Contract Reports (CR) and Technical Reports (TR), which in general are not public. You may however request a copy by using the request-form. In some cases permission may be granted, depending on specific properties and contractor of the report. Reports will be supplied as pdf-file.

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Recent Submissions

Developing a Qualification and Testing Framework for Cold Spray Repairs in Aerospace Applications
(MDPI, 2026) Stamoulis, K.; Abouhamzeh, M.; Bosma, G.A.; Anderiessen, L.; Pascoe, J.-A.
Cold spray is a solid-state deposition technology with great potential for coating and repair applications. This study examines the compliance of the cold spray repair process with a qualification and testing framework based on the requirements set by the European Union Aviation Safety Agency (EASA). As part of this effort, the case study of a repair of a Main Landing Gear (MLG) aluminium component is investigated to demonstrate the applicability of the proposed framework. This framework integrates mechanical and microstructural evaluations, including bond strength, hardness profiling and microstructural characterisation according to relevant ASTM and ISO standards. Experimental results from post-repair testing indicated promising performance, while ongoing testing is aligning reasonably with expected benchmarks and showing compliance with the EASA requirements.
Human–AI Teaming in the Cockpit: From Theory to Practice
(MDPI, 2026) Kox, E.S.; Rooij, J.M. van; Zon, G.D.R.; Kirwan, B.
Crew Resource Management (CRM) in aviation is grounded in principles derived from human–human teamwork, such as the Big Five model of Teamwork (B5T). With the advent of AI-based systems, which could one day take on increasingly complex roles in the cockpit, it remains unclear whether these principles will remain applicable or risk becoming outdated. This study examines how human teamwork concepts translate to use-case-based human–AI collaboration. Five contemporary aviation human–AI teaming use cases are examined by two groups (four Human Factors experts and four professional pilots who are also CRM experts) using B5T and CRM as frameworks. Although the two expert groups are small and are reviewing use cases rather than observing actual pilot behaviour, these early findings suggest that teamwork (B5T) elements and CRM core competencies can be useful for identifying potential positive and negative impacts of AI-based systems on human teamworking, and hence operational risk. Candidate augmentations to B5T are identified to increase its adaptation to human–AI teaming system assessment, and preliminary new CRM training avenues are proposed to enable pilots to better accommodate future AI assistance in the cockpit.
Sizing Uncertainty in Time-of-Flight Diffraction by Monte Carlo Modeling
(MDPI, 2026) Goto, D.T.; Volker, A.W.F.; Maljaars, J.
This study provides a method to estimate of the sizing error of Time-of-Flight Diffraction (TOFD) using a calibration/inspection procedure and a TOFD instrument in accordance with ISO 10863 and ISO 16828. This estimate is based on Monte Carlo simulations using distributions of the underlying error sources. The objective is to estimate the distribution of the flaw height sizing error and to rank the factors affecting the sizing error in a TOFD inspection. The proposed method is demonstrated on a T-shaped carbon steel welded connection with wall thickness 40 mm and flaws with flaw height 5 mm from the back wall. This is a common detail in welded bridges and TOFD is a frequently used inspection technique for fatigue cracks in such a detail. This demonstration case poses two practical challenges. First, for some old bridges, there are no reference blocks of the same material for calibration. This could possibly lead to errors propagated from the calibration. Second, the practice of inspecting the weld by scanning parallel to the weld bead may result in uncertainty of the flaw location relative to the instrument midplane. We found that the errors propagated from calibration are irrelevant for the case of study, and the major contributors to the flaw height sizing error are the uncertainty in picking time-of-flight on the ultrasonic signal and the position of the flaw with respect to the midplane of the TOFD instrument. This last factor is also the main contributor to the systematic underestimation of the flaw height (95% sizing error interval of −1.1 mm in the considered inspection scenario).
Spare mental capacity is related to oxyhemoglobin concentrations (HbO) in the prefrontal cortex and heart rate (variability) : Exploring the relationship between changes in spare mental capacity and multimodal (psycho)physiological measurements in a multitask environment
(SfNIRS, 2022) Miltenburg, M.P.G. van; Zon, G.D.R.; Mohr, T.
Exploring the relationship between changes in spare mental capacity and multimodal (psycho)physiological measurements in a multitask environment.
Additive manufacturing of graphene-reinforced copper matrix composites produced via cold spray
(Elsevier, 2026) Zarei, F.; Lordejani, A.A.; Lee, H.; Ruan, S.; Koutsioukis, A.; Guo, X.; Jafari, D.; Yin, S.; Nicolosi, V.; Dosta, S.; Wits, W.W.; Lupoi, R.; Guagliano, M.; Bagherifard, S.
Graphene (Gr)-reinforced composites offer significant potential for enhanced thermal, mechanical, and functional performances, yet their fabrication via energy beam-based additive manufacturing (AM) is challenging due to the thermal sensitivity of Gr, the risk of agglomeration, and limitations of high-temperature processes. As a solution, Cu-1 wt% Gr deposits were successfully produced using cold spray additive manufacturing (CSAM), providing a solid-state route to fabricate dense 2D metal matrix composites (2DMMCs). The effects of Gr incorporation and gas temperature were systematically investigated on microstructural evolution, dynamic recrystallization, and functional properties. 2DMMCs properties were compared with pure Cu to isolate the effects of Gr reinforcement. The effect of microstructural homogenization induced by post-deposition heat-treatment was analysed on thermal, electrical and mechanical performances. Findings indicate that the presence of Gr alters how strain and thermal energy are distributed within the deposits, promoting heterogeneous microstructures and increasing microhardness. Higher gas temperature led to higher density and thermal conductivity. However, mechanical and electrical properties were moderately reduced due to Gr-induced stress concentrations and interparticle bonding limitations. Subsequent post-deposition annealing partially reduced bulk defects and led to enhanced thermal and electrical performance. Our findings demonstrate that CSAM enables the efficient production of Cu–Gr 2DMMCs. The structure–property relationships established in this work identify interfacial bonding and Gr distribution as the key factors governing composite performance, providing a foundation for future optimization of solid-state AM strategies for large scale 2DMMCs.