17 research outputs found
Instrumented indentation microscope applied to the elastoplastic indentation contact mechanics of coating/substrate composites
Quantitative assessment and prediction of the contact area development during spherical tip indentation of glassy polymers.
This paper describes the development of the contact area during indentation of polycarbonate. The contact area was measured in situ using an instrumented indentation microscope and compared with numerical simulations using an elasto-plastic constitutive model. The parameters in the model were obtainedusing macroscopic tests. Indentations were performed on samples with different thermal histories and at different speeds. For all cases, the numerical modelcorrectly predicted the development of the contact area during indentation. For increasing strain rates, the contact area decreased at equal indentation depths. Annealing the samples resulted in a smaller contact area at equal indentation depth. Using only numerical simulation, it was also shown that pile-up around the indenter resulted from localization effects and was, thus, promoted by strainsofteningproperties of the indented material. Strain hardening, on the other hand, will tend to promote sink-in. Finally, we performed simulations of loadrelaxation during indentation. The results indicate that about 40% of the total observed relaxation may be assigned to plastic effects
Quantitative assessment and prediction of contact area development during spherical tip indentation of glassy polymers
State of the art and research challenges in the area of autonomous control for a reliable internet of services
The explosive growth of the Internet has fundamentally changed the
global society. The emergence of concepts like service-oriented architecture
(SOA), Software as a Service (SaaS), Platform as a Service (PaaS), Infrastructure
as a Service (IaaS), Network as a Service (NaaS) and Cloud Computing in
general has catalyzed the migration from the information-oriented Internet into
an Internet of Services (IoS). This has opened up virtually unbounded possibilities
for the creation of new and innovative services that facilitate business
processes and improve the quality of life. However, this also calls for new
approaches to ensuring quality and reliability of these services. The goal of this
book chapter is to first analyze the state-of-the-art in the area of autonomous
control for a reliable IoS and then to identify the main research challenges within
it. A general background and high-level description of the current state of
knowledge is presented. Then, for each of the three subareas, namely the
autonomous management and real-time control, methods and tools for monitoring
and service prediction, and smart pricing and competition in
multi-domain systems, a brief general introduction and background are presented,
and a list of key research challenges is formulated