Internal strains are present in practically all heterogeneous materials. Their mamagnitude depends on processing conditions, material properties, and extend of the heterogeneity as well as the mechanical and environmental loads. Their characterization, however, is not trivial and classical techniques lack sufficient resolution.

Optical fibers with Bragg Grating (FBG) sensors have attracted considerable attention over the last years due to their characteristic property to measure strains in the host structure at the location of the grating. They are particularly adapted to polymeric materials where they can be embedded during processing and provide, virtually non-invasive, internal strain or temperature measurements at selected locations in the structure. Over the past years, we have been active in research in mechanics of materials with the use of Bragg gratings to measure internal strains. Particular emphasis has been placed in metrology of embedded FBG sensors, processing, and durability, low energy impact of composite plates and fracture and fatigue of composites. Single short, or long FBGs, are used or several ones in wavelength multiplexing.

In this presentation, the essential aspects of FBG sensors as a tool for internal strain measurements are reviewed. In particular, the response of the FBG signals in non-homogeneous strain fields, non-symmetric lateral loads as well as lateral pressure is discussed in some details. This research is of paramount importance for the accurate interpretation of the FBG signals in the multitude of strain environments encountered in the sensor’s host structure response. Afterwards, examples of strain measurements with embedded FBGs in specific problems of fracture and fatigue are discussed and involve experimental characterization and numerical models to predict their response.

Chemical Dynamics aims to understand the mechanisms that drive chemical reactions in their quantum detail. For any given reaction, this understanding includes mapping of all possible combinations of energies and orientations of reactants and products that lead to or result from reactive collisions. Achieving that, even for an elementary chemical reaction, is a monumental task, requiring a combination of theory and experiment: theory predicts what energies and orientations work and experiment confirms the prediction or points out what changes are needed.

In this talk, we will examine elements of the current state of the art in the field of experimental Chemical Dynamics, recent advances and future prospects. In photodissociation dynamics, we will focus on reaction product imaging results of highly excited small molecules. In structural dynamics, we will discuss our progress towards a time-resolved electron diffractometer, aiming to monitor structural changes during chemical reactions with high spatial and temporal resolution. Finally, in photoelectron dynamics, we will report on first results of nanosecond photoelectron circular dichroism experiments, a promising way to study chirality and separate chiral mixtures using lasers.