- Yes, there are practical techniques employed to stop or mitigate the propagation of cracks in composite materials. Incorporating reinforcing materials, such as fibers or particles, into the composite matrix can enhance its resistance to crack propagation. The reinforcements help distribute the stress and prevent cracks from spreading. In laminated composite materials, interlaminar toughening techniques involve introducing toughened layers between the laminae. This helps prevent the propagation of cracks between adjacent layers.
- Utilizing resin systems that are specifically formulated for toughness can enhance the material's ability to resist crack growth. Toughened resins absorb more energy during deformation, making them more resistant to crack propagation. Adding nanoparticles to the composite material can improve its mechanical properties, including resistance to crack propagation. Nanoparticles can act as barriers and hinder crack growth. Heat treatments or chemical treatments after the manufacturing process can alter the material's properties and improve its resistance to crack propagation.
The selection of the most appropriate technique depends on factors such as the specific composite material, intended application, and environmental conditions. It often involves a combination of some these methods to achieve optimal crack resistance.
A small addition to exhaustive answer given Amira Dellagi: propagation of cracks in a composite material may be decelerated by creating of compressive stresses in zones of cracks initiation.
Based on the above answers and my research on ChatGPT at a glance, my opinion is that the material that is not pre-designed for mitigating crack propagation, such as self-healing properties, as mentioned by Amira. We have few opportunities to completely stop the crack propagation. There are several techniques to monitor the cracks. And de-accelerating, as mentioned by Serge.
Poisson's ratio is the key parameter from available recent theoretical analyses (our works involving Poisson's effect in compression). We may say that in large structures (say of the order of several meters), composites with lamellae materials with zero or negative Poisson's ratios would increase the resistance to fracture considerably. This is because under compression in gravitational forces, as we are suffering by earth, Poisson's ratio is the driving force under fracture over large distance. This is evidenced in our studies. We use the terminology "Poisson's tensile force", namely the induced tensile force due to Poisson's effect.
P.S. we consider large specimens and not small structures common to laboratory experiments.
Really, Poisson's ratio (PR) determine the compressibility of materials and I agree with Prof. Anongba about role of PR sign in crack evolution which is similar to microslip process in frictional contact (see, please, our study of self-healing effect caused by to auxetic (negative PR) behaviour.
All the best,
Serge
Good morning,
From a purely material point of view, it is possible to add fillers allowing self-healing in-situ; these techniques are quite well described in the literature. In certain cases, it is also possible to use dry preforms woven in 3D, then implemented by RTM for example. This helps the composite to be more resistant in 3 dimensions, and therefore make it less fragile.
The question has no general answer. An example of each material should be considered separately
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