Coastal Blue Carbon Opportunity Assessment for Snohomish Estuary: The Climate Benefits of Estuary Restoration

This report presents the findings of a groundbreaking study that confirms the climate mitigation benefits of restoring tidal wetland habitat in the Snohomish Estuary, located within the nation's second largest estuary: Puget Sound. The study, the first of its kind, finds major climate mitigation benefits from wetland restoration and provides a much needed approach for assessing carbon fluxes for historic drained and future restored wetlands which can now be transferred and applied to other geographie

Literatuurstudie naar de sociaal – economische betekenis van de Nederlandse voedings- en genotmidelenindustrie

Deze notitie beschrijft een kortlopende literatuurstudie naar de sociaal-economische betekenis van de Nederlandse voedings- en genotmiddelenindustrie en de concurrentiekracht. Er is geen aandacht besteed aan toekomstige ontwikkelingen. Binnen deze kortlopende literatuurstudie richten de auteurs zich met name op de Nederlandse voedings- en genotmiddelenindustrie, haar concurrentie- en innovatiekracht. Hieruit volgt een sterkte/zwakte analyse van de industrie en een aantal beleidsactiepunten voor het bedrijfsleven en de overheid aan de hand van conclusies en aanbevelingen. In de studie ligt de focus op de voedings- en genotmiddelenindustrie

A 3D modelling approach for fluid progression during process simulation of wet compression moulding - Motivation & approach

Wet compression moulding (WCM) provides large-scale production potential for continuous fibre-reinforced structural components due to simultaneous infiltration and draping during moulding (viscous draping). Due to thickness-dominated infiltration of the laminate, comparatively low cavity pressures are sufficient – a considerable economic advantage. Experimental and numerical investigations prove strong mutual dependencies between the physical mechanisms, especially between resin flow and textile forming. Understanding and suitable modelling of these occurring physical mechanisms is crucial for process development and final part design. While existing modelling approaches are suitable for infiltration of preformed fabrics within various liquid moulding technologies, such as CRTM/RTM or VARI, WCM requires a fully coupled simulation approach for resin progression and concurrent stack deformation. Thus, the key challenge is to efficiently link these two aspects in a suitable framework. First, this work demonstrates that a three-dimensional approach for fluid progression during moulding is needed to capture WCM-process boundary conditions. In this regard, a novel test bench is used to investigate the impact of infiltration on the transversal compaction behaviour of a woven fabric. Moreover, the test setup is applied to determine the in-plane permeability values of the same material corresponding to the beforehand applied compaction states. Results are verified by comparison with an existing linear test setup. In the second part, initial steps towards a three dimensional extension of an existing 2D modelling approach are outlined. For this purpose, a macroscopic FE-based three-dimensional formulation of Darcy’s law is utilized within a User-Element in Abaqus/Explicit. Essential mechanisms within the element are presented. Additional control volumes (FE/CV) are applied to ensure mass conservation. Eventually, it is demonstrated, that the simulation model can predict the average fluid pressure beneath a punch during pre-infiltrated compaction experiments. Finally, major benefits and forthcoming steps for a fully-coupled 3D modelling approach for WCM are outlined

Capabilities of macroscopic forming simulation for large-scale forming processes of dry and impregnated textiles

Forming of continuously fibre-reinforced polymers (CoFRP) has a significant impact on the structural performance of composite components, underlining the importance of forming simulation for CoFRP product development processes. For an integrated development of industrial composite components, efficient forming simulation methods are in high demand. Application-oriented method development is particularly crucial for industrial needs, where large and complex multi-layer components are manufactured, commercial FE software is used, and yet high prediction accuracy is required. To meet industrial demands, this contribution gives an insight in macroscopic forming simulation approaches that utilize the FE software Abaqus in combination with user-defined material models and finite elements. Three CoFRP forming technologies are considered, which are in industrial focus due to their suitability for mass production: textile forming of dry unidirectional non-crimp fabrics (UD-NCF), thermoforming of pre-impregnated UD tapes and wet compression moulding (WCM). In addition to the highly anisotropic, large-strain material behaviour that composite forming processes have in common, the three process technologies face various process-specific modelling challenges. UD-NCFs require material models that capture the deformation behaviour and the slippage of the stitching. Thermoforming of UD tapes is highly rate- and temperature-dependent, calling for rheological membrane and bending modelling. Moreover, a thermomechanical approach including crystallisation kinetics enables the prediction of potential phase-transition during forming and resulting defects in the semi-crystalline thermoplastic matrix. For simultaneous forming and infiltration in wet compression moulding, a finite Darcy-Progression-Element is superimposed with the membrane and shell elements for forming simulation, capturing infiltration-dependent material properties. The three outlined technologies illustrate the complexity and importance of further simulation method development to support future process development

Experimental and numerical investigation of the shear behaviour of infiltrated woven fabrics

Wet compression moulding (WCM) as a promising alternative to resin transfer moulding (RTM) provides high-volume production potential for continuously fibre reinforced composite components. Lower cycle times are possible due to the parallelisation of the process steps draping, infiltration and curing during moulding. Although experimental and theoretical investigations indicate a strong mutual dependency arising from this parallelisation, no material characterisation set-ups for textiles infiltrated with low viscous fluids are yet available, which limits a physical-based process understanding and prevents the development of proper simulation tools. Therefore, a modified bias-extension test set-up is presented, which enables infiltrated shear characterisation of engineering textiles. Experimental studies on an infiltrated woven fabric reveal both, rate- and viscosity-dependent shear behaviour. The process relevance is evaluated on part level within a numerical study by means of FE-forming simulation. Results reveal a significant impact on the global and local shear angle distribution, especially during forming

Material modeling in forming simulation of three-dimensional fiber-metal-laminates - A parametric study

Forming of fiber-metal-laminates (FML) into complex geometries is challenging, due to the low fracture toughness of the fibers. Several researchers have addressed this topic in recent years. A new manufacturing process has been introduced in our previous work that successfully combines deep drawing with thermoplastic resin transfer molding (T-RTM) in a single process step. During molding, the fabric is infiltrated with a reactive monomeric matrix, which polymerizes to a thermoplastic after the forming process is completed. In our previous work, a numerical modeling approach was presented for this fully integrated process, investigating a hybrid laminate with 1 mm thick metal sheets of DC04 as top layers and three inner glass fiber layers. Although initial results were promising, there were still some pending issues regarding the modeling of material behavior. The current study aims to address several of these open issues and to provide a general modelling framework for future enhancements. For this purpose, the existing modelling approach is extended and used for parameter analysis. Regarding the influence of different material characteristics on the forming result, shear, bending and compression properties of the fabric are modified systematically. It is shown, that the compression behavior and particularly the tension-compression anisotropy of the fabric is of high importance for modelling the combined forming of fabric and metal. The bending and shear properties of the fabric are negligible small compared to the metal stiffness which dominates the draping process. Finally, it is demonstrated that modelling the fabric layers using continuum shells provides a promising approach for future research, as it enables a suitable way to account for transversal compaction during molding

An Ecogeomorphic Model to Assess the Response of Padilla Bay\u27s Eelgrass Habitat to Sea Level Rise

Estuaries worldwide are facing the possibility of conversion to open water if accretion cannot keep pace with increasing rates of sea level rise. Recent research into sediment elevation dynamics in Padilla Bay, a National Estuarine Research Reserve in Puget Sound, has revealed a mean bay-wide elevation deficit of -0.37 cm yr-1 since 2002. However, a more mechanistic prediction of the estuary’s response to future sea level rise should also incorporate non-linear feedback mechanisms between water depth, plant growth, and sediment deposition. Therefore, I used measurements of sediment accretion rates, suspended sediment concentrations, eelgrass stem density, and above- and belowground eelgrass biomass to build and calibrate a marsh equilibrium model (MEM), developed elsewhere but applied here for the first time to this eelgrass-dominated intertidal habitat. I then coupled the MEM with a relative elevation model (REM), which has previously been applied here, to create a hybrid that combines each model’s strengths in mechanistically simulating above- and belowground processes, respectively. The model predicts elevation change under various scenarios of sea level rise and suspended sediment concentrations. I used a 12-year elevation change dataset obtained from an extensive surface elevation table (SET) network in Padilla Bay for model validation. Field measurements indicated sediment accretion rates to be primarily determined by eelgrass stem density instead of biomass or relative elevation. I modified the hybrid model to reflect this relationship, which differentiates it from its predecessors. The model validation exercise revealed the need for an erosion parameter, without which projected relative elevation gain was substantially overestimated. Model projections without erosion showed an increase in relative elevation over much of the bay’s elevation gradient over a 100-year timeframe, reaching an equilibrium at an elevation where Zostera japonica stem density is maximized. These scenarios would involve an increase in Z. japonica cover in Padilla Bay, and a decrease in Z. marina cover. In contrast, model projections with erosion revealed a loss in relative elevation along the entire elevation gradient for all but the most conservative sea level rise scenario. The magnitude of loss was predicted to be greater at higher elevations. The suspended sediment concentrations required for the bay to maintain a stable relative elevation were higher than the current concentration of 3.93 mg L-1 for all sea level rise scenarios, with up to 15 mg L-1 being required for the most extreme scenario