Acoustic Product Release

Acoustic Product Release

Developing an automated demoulding method using sonic actuators.

This research is carried out by Anouar Elsayed with the aim to investigate, develop and validate a method for automatically demoulding a composite part after vacuum infusion by utilising sonic elements.

Figure 1: Typical vacuum infusion process

The composites industry has shown a significant growth over the last decade, there is constantly more demand for lightweight materials and structures all over the globe and for different industries like the automotive, aeronautical and wind energy. There is large space for development development in the industry and one of the biggest and most required developments is the automation of the production processes. One of the most popular production processes in the composites industry is the vacuum infusion process.

In general, the separation process requires lots of force, especially if the design is complex and includes very sharp corners. Conventionally most manufacturers perform the demoulding process manually for small products and semi-manually with cranes for large products. After an infusion is cured the part must be released from the mould, this process is considered a critical moment in the production process because There is always a percentage of failure of a demoulding procedure, this is due to several factors like design of the mould, poor application of release agent or sealer and uncured mould surfaces. A poor demoulding process can result in a bad quality product or a damaged product that requires further adjustments and fixing. This project attempts to investigate and validate a new method to automate the demoulding process using new techniques that utilise vibrations.

Figure 2: manual demoulding of product
Figure 3: damaged mould from manual demoulding

The theory behind this research is based on resonance, each body has specific resonance frequencies when subjected to it, the body resonates into a certain mode shape unique to that specific frequency. This theory is applied to the product inside the mould to resonate it from its position and eventually release it from the mould. First, an investigation is done on the most suitable method and elements that can be used to generate and apply the vibrations to the laminate, this resonator is then build and tested to fit the requirements set for demoulding. Afterwards, a test mould is build using all information gained from the literature study about the problems that cause a product to get stuck on a mould. Later after the shape and dimensions of the product are determined, a CAD model is created and a modal analysis and Harmonic response analysis is performed to obtain the natural frequencies and mode shapes and displacements of the product according to each resonance frequencies. the analysis showed that there are 3 specific mode shapes that should directly resonate the surfaces that are suspected to be stuck on the mould.

The results of the analysis are put to the test using the test mould and the resonator and each mode shape was performed with the corresponding frequency. The results of the test showed that the laminate did respond by slightly resonating and displacing from its position but not enough to hold the simulated mode shape calculated in the analysis. This means that the theory is plausible, and further investigation is required in certain areas of the research like the effect of the mould when resonating the product and the dampening caused by the resonator itself on the laminate surface.