Life cycle monitoring of composite aircraft components with structural health monitoring technologies

Life cycle monitoring could considerably improve the economy and sustainability of composite aircraft components. Knowledge about the quality of a component and its structural health allows thorough exploitation of it’s useful life and offers opportunity for optimization. Current life cycle monitoring efforts can be split in two main fields 1) process monitoring and 2) structural health monitoring with little overlap between them. This work aims to propose an integral monitoring approach, enabling entire life monitoring with the same sensor. First, the state of the art of both composite manufacturing as well as structural health monitoring technologies is presented. Piezoelectric sensors have been ruled out for further investigation due their brittleness. Fiber optical sensors and electrical property-based methods are further investigated. Distributed fiber optic sensors have been successfully used in composite manufacturing trials. Two processes were demonstrated: vacuum assisted resin transfer molding and resin infusion under flexible tooling. Due to their flexibility, optical fibers can survive the loads occurring during manufacturing and deliver valuable insights. It is shown for the first time numerically and experimentally, that fiber bed compaction levels and volume fractions can be calculated from the optical frequency shift measured by the optical fiber sensors. The same sensor was used for subsequent structural health monitoring. This proves that the gap between process monitoring and structural health monitoring can be closed with mutual benefits in both areas. The final chapter presents a novel electrical property-based sensing technique. The sensors are highly flexible and manufactured with a robot-based 3D-printing method. They are shown to reliably work as strain sensors and crack detectors. This work presents a thorough investigation of available and novel sensing technologies for process monitoring and structural health monitoring settings. The results obtained could pave the way to more efficient aircraft structures.Open Acces

Life Goals Across Adulthood and Old Age: Associations With Personality and Well-Being

Life goals are what people talk about when asked what makes a successful life. Based on the assumption that the judgement of what is important and desirable in life changes with age, this dissertation investigated the life span development of important life goals like having children, career success, or self-fulfillment and their developmental relationships with the Big Five personality traits and eight different aspects of well-being. The three empirical studies are based on six to 30 waves of data from the German socio-economic panel (SOEP) and span study periods of 13 to 30 years. Study I examined the lifespan development of nine life goals and tested if gender, parental status (i.e., if someone is a biological parent or not), education, and regional socialization (former East versus West Germany) influenced development. The results suggest that life goals evolve through periods of stability and change, which correspond to age-graded developmental tasks, shifts in future time perspective, and generativity orientation. Mean-level changes in normative life goals that are closely tied to societal scripts, such as career success and having children, exhibited stronger alignment with typical age-grading in developmental tasks, while less normative goals that can mean different things to different people (e.g., self-fulfillment) changed independently. Of all investigated moderators, gender and parental status had the strongest impact on development. The goals career success and having children selected women, but not men into parenthood. Parenthood amplified existing traditional gender role conforming differences (i.e., compared to women, men perceived career success as more important and family goals as less important). Study II was the first large-scale longitudinal study to examine the codevelopment of life goals and the Big Five personality traits in a sample that is heterogeneous in terms of age and education. It investigated if change in the importance of life goals goes hand in hand with change in the Big Five and if this conjoint change depends on a person’s age, perceived control, gender, education, and regional socialization. The results suggest a weak to moderate relationship between changes in life goals and changes in the Big Five. The strongest codevelopment concerned personal growth goals (i.e., self-fulfillment) and Openness, followed by communal goals (i.e., being there for others) and Agreeableness. Career goals codeveloped with Conscientiousness. Normative life goals that are strongly tied to social scripts (e.g., having children or career success) codeveloped more strongly with traits during midlife (ages 25-59), whereas less scripted life goals (e.g., self-fulfillment) codeveloped with traits across the entire lifespan. Study III employed a rigorous case-controlled longitudinal design to investigate how achieving or disengaging from normative developmental goals impacted mental health, well-being, and loneliness across young adulthood and midlife. To do so it focused on the goal to have children and examined how the perceived importance to have children and career success assessed in early adulthood (ages 18-30) affected the midlife well-being trajectories of people without children and parents. The results showed that the mental health, well-being, and loneliness trajectories of people without children and parents largely converged. The largest differences concern established adulthood (ages 30-45). Supporting developmental regulation theories, prioritizing the goal to have children during early adulthood was found to negatively affect the midlife mental health and well-being of adults who remain childfree whereas prioritizing career success was found to negatively affect the well-being of parents. Disengaging from the goal to have children in midlife was beneficial for the well-being of people without children as well as for the work satisfaction of parents. Study III shows that what we prioritize when we are young can have long-lasting effects on mental health and well-being, especially if we fail to adjust our goals.Lebensziele sind das, worüber Menschen sprechen, wenn sie gefragt werden, was ein erfolgreiches Leben ausmacht. Basierend auf der Annahme, dass sich die Einschätzung dessen, was im Leben wichtig und erstrebenswert ist, mit dem Alter ändert, untersuchte diese Dissertation die lebenslange Entwicklung wichtiger Lebensziele wie die Familiengründung, beruflichen Erfolg oder Selbstverwirklichung und ihre Entwicklungsbeziehungen zu den Big Five Persönlichkeitsmerkmalen sowie zu acht verschiedenen Aspekten des Wohlbefindens. Die drei empirischen Studien basieren auf sechs bis 30 Datenwellen des Deutschen Sozio-ökonomischen Panels (SOEP) und erstrecken sich über Untersuchungszeiträume von 13 bis 30 Jahren. Studie I untersuchte die lebenslange Entwicklung von neun Lebenszielen und prüfte, ob Geschlecht, Elternschaft, Bildung und regionale Sozialisation (ehemaliges Ost- versus Westdeutschland) diese Entwicklung beeinflussen. Die Ergebnisse legen nahe, dass Lebensziele Phasen von Stabilität und Veränderung durchlaufen, welche die altersabhängigen Entwicklungsaufgaben, Veränderungen in der Zeitperspektive und Generativitätsorientierung widerspiegeln. Veränderung und Stabilität normativer Lebensziele, die stark an soziale Skripte gebunden sind (z. B. beruflicher Erfolg oder Elternschaft), korrespondierten stärker mit typischen Entwicklungsaufgaben, während sich weniger normative Ziele, die für verschiedene Menschen unterschiedliche Bedeutungen haben können (z. B. Selbstverwirklichung), unabhängig veränderten. Von allen untersuchten Moderatoren hatten Geschlecht und Elternschaft den stärksten Einfluss auf die Entwicklung. Die Ziele Kinder zu bekommen und beruflicher Erfolg selektieren Frauen, aber nicht Männer in Elternschaft. Elternschaft verstärkte bestehende Unterschiede, die den traditionellen Geschlechterrollen entsprachen (d. h. im Vergleich zu Frauen betrachteten Männer beruflichen Erfolg als wichtiger und familiäre Ziele als weniger wichtig). Studie II war die erste groß angelegte Längsschnittstudie, welche die gemeinsame Entwicklung von Lebenszielen und den Big Five Persönlichkeitsmerkmalen in einer alters- und bildungsheterogenen Stichprobe analysierte. Sie untersuchte, ob Veränderungen in der Bedeutung von Lebenszielen Hand in Hand mit Veränderungen in den Big Five gehen und, ob diese gemeinsame Veränderung von Alter, wahrgenommener Kontrolle, Geschlecht, Bildung und regionaler Sozialisation einer Person abhängt. Die Ergebnisse legen nahe, dass eine schwache bis moderate Beziehung zwischen Veränderungen in Lebenszielen und Veränderungen bei den Big Five besteht. Der stärkste längsschnittliche Zusammenhang bestand zwischen persönliche Wachstumszielen (Selbstverwirklichung) und Offenheit, gefolgt von gemeinschaftlichen Zielen (für andere da sein) und Verträglichkeit. Berufsziele entwickelten sich zusammen mit Gewissenhaftigkeit. Normative Lebensziele, die eng an gesellschaftliche Erwartungen geknüpft sind (z.B. Familiengründung oder beruflicher Erfolg), veränderten sich insbesondere während der Lebensmitte (im Alter von 25-59 Jahren) gemeinsam mit den Big Five, während weniger normative Lebensziele (z.B. Selbstverwirklichung) sich über die gesamte Lebensspanne hinweg gemeinsam mit Persönlichkeitsmerkmalen veränderten. Studie III untersuchte mit Hilfe von Propensity Score Matching, wie das Erreichen oder Loslassen von normativen Entwicklungszielen die psychische Gesundheit, das Wohlbefinden und die Einsamkeit im jungen Erwachsenenalter und in der Lebensmitte beeinflusst. Im Fokus der Studie lag das Ziel Elternschaft. Untersucht wurde, wie die im frühen Erwachsenenalter (18-30 Jahren) erfasste wahrgenommene Bedeutung von Familiengründung und beruflichem Erfolg, die Entwicklung des Wohlbefindens von Personen ohne Kinder und Eltern beeinflussten. Die Ergebnisse zeigten, dass die Verläufe der psychischen Gesundheit, des Wohlbefindens und der Einsamkeit von Menschen ohne Kinder und Eltern weitgehend konvergierten. Die größten Unterschiede traten im Alter zwischen 30 und 45 Jahren auf. Die Ergebnisse stützen Theorien der Entwicklungsregulation und zeigen, dass das Priorisieren von Familiengründung im frühen Erwachsenenalter sich negativ auf die spätere psychische Gesundheit und das Wohlbefinden von kinderlosen Erwachsenen auswirkte, während das frühe Priorisieren von beruflichem Erfolg sich negativ auf das Wohlbefinden von Eltern auswirkte. Das Abwerten des Ziels Kinder zu haben im mittleren Erwachsenenalter hatte einen positiven Effekt auf das Wohlbefinden kinderloser Personen und einen positiven Effekt auf die Arbeitszufriedenheit von Eltern. Studie III zeigt, dass das, was wir in jungen Jahren priorisieren, langanhaltende Auswirkungen auf die psychische Gesundheit und das Wohlbefinden haben kann, insbesondere wenn wir es versäumen, unsere Ziele anzupassen

Expectation-driven interaction: a model based on Luhmann's contingency approach

We introduce an agent-based model of interaction, drawing on the contingency approach from Luhmann's theory of social systems. The agent interactions are defined by the exchange of distinct messages. Message selection is based on the history of the interaction and developed within the confines of the problem of double contingency. We examine interaction strategies in the light of the message-exchange description using analytical and computational methods.Comment: 37 pages, 16 Figures, to appear in Journal of Artificial Societies and Social Simulation

Expectation-Driven Interaction: a Model Based on Luhmann's Contingency Approach

We introduce an agent-based model of interaction, drawing on the contingency approach from Luhmann\'s theory of social systems. The agent interactions are defined by the exchange of distinct messages. Message selection is based on the history of the interaction and developed within the confines of the problem of double contingency. We examine interaction strategies in the light of the message-exchange description using analytical and computational methods.Contingency, Message Exchange Model, Interaction, Expectation-Expectation, Asymptotic Analysis

Vacuum assisted resin transfer moulding process monitoring by means of distributed fibre-optic sensors: a numerical and experimental study

A novel composite manufacturing process monitoring application using fibre-optic (FO) sensors is reported for vacuum-assisted resin transfer moulding (VaRTM) with a rigid-closed mould. A fully distributed Rayleigh-Backscattering based load-monitoring approach is demonstrated by numerical modelling and experimental application. Lateral fabric compression is reliably tracked throughout the entire VaRTM process, giving live insights on local pressure distribution, fabric stack compaction and fibre-volume fraction. These parameters have a great influence on the quality of fibre-reinforced composites and real-time tracking of them will significantly improve the quality of the manufactured part, while reducing the number of scraps and destructive testing. The final fibre volume fraction of a medium-sized plate manufactured using industrial VaRTM equipment was successfully predicted based on embedded FO sensor readings only. With a low bend-loss single mode optical fibre sensor being designed for process survivability and forming an integral part of the composite component, it enables a true entire life-cycle monitoring

A Comparison Between an Individual and a Collaborative Versions of a Serious Game to Learn About Dengue Fever

Dengue fever is a major infectious disease caused by arbovirus and there is no vaccine yet; prevention is the action which raises the importance of an educational approach. The use of games to help in the educational process can be motivating and effective but it is not clear which interaction approach is the best: individual or collaborative. A comparative study on a between subject (n=73) experiment using a single player and a pair based version of a serious game that teaches about Dengue fever has been performed. Both versions performed well but presented different advantages: single player version can be used for consulting more easily, and the pair-based game seems to be slightly more motivating to the point that players would be more willing to suggest it to someone else. Data suggest that each interaction approach has its role in the educational process and should be carefully evaluated against educator’s intents

Dimensions of Accountability in Inter-organizational Business Processes

Inter-organizational business processes are the basis of a globalized, highly dynamic, and digitalized world, en-abling faster and cost-effective transactions. At the same time, they raise business vulnerabilities. A partic-ular vulnerability is linked to the substantiation of trust between actors in dynamic business relationships, as trust affects interdependencies and complexity. An ap-proach to address this vulnerability is the introduction of accountability mechanisms. Extant research suggests that accountability enables revealing causality and a transparent allocation of responsibilities for each pro-cess step. Thereby, corresponding actors can judge upon misbehavior and verify trust claims. Unfortu-nately, a thorough understanding of accountability and its dimensions accountability in the context of IBP is still missing. To address this gap, we develop a framework with dimensions of accountability. We demonstrate the resulting framework in an industrial supply chain case and derive implications for theory and practice

From Loyalty Points to Virtual Currencies: Expanding Loyalty Schemes for Mobile Platforms

Since the first loyalty program was introduced in the 1980s, technological innovation has changed the possibilities for such programs considerably. One significant change is the emergence of mobile and online platforms that started to deploy loyalty schemes aiming at both sides of the market, namely customers and third parties such as retailers or merchants. One consequence is the expansion of the roles of loyalty measures to the point of introducing a Virtual Currency. More than plain loyalty points, Virtual Currency is a tool to support multiple usage options granted to different types of users and utilizations. Based on the analysis of four case studies, this paper examines the business conditions and consequences of the implementation of a Virtual Currency by mobile and online platforms. One consistent element throughout all examples is the aspect of rewarding customers for desired user actions. Beyond this, the objectives of implementing a Virtual Currency go from strengthening loyalty to opening new revenue streams. The paper contributes to gain insights of how loyalty measures and rewarding schemes can be transformed and expanded to Virtual currency programs and how respective strategies can impact platforms’ business models and hence performance in the market