Mon, 29 November, 2021
At the Enhanced Composites and Structures Centre at Cranfield University, we have been developing a process for integrating SEER sensors into the composite tooling. One of the key sensor integration challenges in SEER is minimising the local damage and tow distortion in the tool surrounding integrated sensors. In SEER, we have opted for integrating the sensors into the tool ahead of the curing process using a novel through-thickness reinforcement process. By doing this, we avoid drilling into the composite, causing excessive potential damage. However, it is unclear how we can manipulate this process to achieve the best possible sensor insertion in which fibres are steered around the sensor and contribute to load bearing rather than being sliced.
As part of this work, one of our objectives is to investigate the mechanics surrounding our through-thickness reinforcement insertion for sensor insertion. A key element of characterising this insertion process is the development of a validated mesoscale model that simulates sensor insertion and captures tow deformation and damage characteristics in a Representative Volume Element (RVE) of the tooling preform. As part of the yearly intake of MSc students, the team was joined by Mr Muhammed Zeeshan Azad, who conducted a 12-week individual research project entitled, “Insertion of through-thickness reinforcing rods in composite tooling,” supervised by Dr Geoffrey Neale and Dr Alex Skordos.
His research activities included the preparation and testing and inspection of samples along with the development of two insertion models (shown below). The first image (figure 1)shows the insertion of the dummy through a single layer of the preform, with the stress field showing regions of large stress build up in areas of large tow deformation. The second image (figure 2) shows a multi-layer insertion model incorporating 3D Hashin damage which can predict when tows fail, either via splitting or cutting, during insertion. The graph (figure 3) compares typical experimental and simulation force versus displacement curves and shows a generally good agreement between the model and experimental results, with a breakdown in the relationship later in the event. This is likely due to a dissimilarity between simulation and experimental boundary conditions and will be improved in future model refinement.
Cranfield University is very pleased with the outcomes of this work will feed into larger thermomechanical models that simulate the performance of the SEER tool.
Want to know more about the work that we do at the Enhanced Composites and Structures Centre at Cranfield?
Enhanced Composites and Structures Centre (cranfield.ac.uk)
The SEER project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 871875.