|
Rubber-like materials, which are often used in dampeners, have a unique property known as dynamic viscoelasticity, which allows them to transform mechanical energy from vibrations into heat while simultaneously showing spring-like and flow-like behaviours.
These materials can be customised by combining them with substances with certain molecular architectures, depending on the dynamic viscosity requirements. However, the underlying mechanisms governing these materials' unique mechanical characteristics remain unknown. The lack of a complete system capable of concurrently measuring mechanical characteristics and viewing the microstructural dynamics of these materials has been a key cause of this knowledge gap. While X-ray computed tomography (CT) has lately emerged as a potential option for non-destructive inspection of the internal structure of materials down to nanoscale resolutions, it is not suitable for dynamic monitoring. Against this backdrop, a team of researchers, led by Associate Professor (tenure-track) Masami Matsubara from the School of Creative Science and Engineering at the Faculty of Engineering at Waseda University in Japan, has now developed an innovative system that can conduct dynamic mechanical analysis and dynamic micro X-ray CT imaging simultaneously. Their study was published in Volume 205 of the journal Mechanical Systems and Signal Processing. "By integrating X-ray CT imaging performed at the large synchrotron radiation facility Spring-8(BL20XU) and mechanical analysis under dynamic conditions, we can elucidate the relationship between a material's internal structure, its dynamic behaviour, and its damping properties," explained Dr Matsubara. At the core of this novel system is the dynamic micro X-ray CT and a specially designed compact shaker developed by the team that is capable of precise adjustment of vibration amplitude and frequency. The team utilized this innovative system to investigate the distinctions between styrene-butadiene rubber (SBR) and natural rubber (NR), as well as to explore how the shape and size of ZnO particles influence the dynamic behaviour of SBR composites. The researchers conducted dynamic micro X-ray CT scans on these materials, rotating them during imaging while simultaneously subjecting them to vibrations from the shaker. They then developed histograms of local strain amplitudes by utilizing the local strains extracted from the 3D reconstructed images of the materials' internal structures. These histograms, in conjunction with the materials' loss factor, a measure of the inherent damping of material, were analyzed to understand their dynamic behaviour. When comparing materials SBR and NR, which have significantly different loss factors, the team found no discernible differences between their local strain amplitude histograms. However, the histograms displayed wider strain distributions in the presence of composite particles like ZnO. This suggests that strain within these materials is non-uniform and depends on the shape and size of the particles, which may have masked any changes from the addition of the particles. "This technology can allow us to study the microstructure of rubber and rubber-like materials under dynamic conditions and can result in the development of fuel-efficient rubber tires or gloves that do not deteriorate. Moreover, this technology can also enable the dynamic X-ray CT imaging of living organs that repeatedly deform, such as the heart, and can even pave the way for the development of artificial organs," said Dr Matsubara, highlighting the importance of this study. (ANI)
|
