Low velocity impact of composites

In summary, when comparing impact toughness for low-velocity applications, it is best to look at Charpy and Izod energies rather than Kic values. These tests can give a good indication of a material's toughness and resistance to fracture. However, it is important to consider the potential variations in results due to different test setups and conditions. It may also be helpful to consult resources such as the NIST database or reach out to material suppliers for data on specific materials and alloys.
  • #1
kyuzokyuzo
1
0
Hi,

I was hoping someone might be able to help with some questions about composite toughness.

I am trying to find an FRP composite with comparable impact toughness and yield strength to 7075 T6 Aluminium. I'm having trouble finding any means of direct comparison. I've read that Kic is not a good measure of low-velocity impact toughness for composites as it varies a lot with impact velocity.

Other properties that I thought might be useful are Izod or Charpy energies. Does anyone know where I can find values for these? I have found data for the Izod and Charpy of many plastics but data for Aluminium seems harder to come by.

I found a paper ( http://nvl.nist.gov/pub/nistpubs/jres/104/6/j46sie.pdf ) about Izod and charpy from which its possible to calculate the charpy of 7075-T6, but this gave a value of around 60 kJ/m^2 and I'd like to check this.

What is the best way to compare impact toughness for a low-velocity application? For composites it seems there is no 'accepted' way that really represents a fundamental material property. Tests so far are all specific to the test setup, impact shape/mass/velocity/hardness etc.

Would it be best to just take Kic and Charpy/Izod results and use them as a rough means of gauging performance. Is there a better way that doesn't involve computation?
 
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  • #2



Hello,

Thank you for your questions about composite toughness. It can be challenging to find direct comparisons between FRP composites and metals like 7075 T6 Aluminium, as they have different material properties and behave differently under impact.

As you mentioned, Kic is not a reliable measure of low-velocity impact toughness for composites. Instead, I would suggest looking at the Charpy or Izod energies, as these are commonly used for impact testing of materials. The Charpy and Izod tests measure the energy absorbed by a material during impact, and their results can give a good indication of a material's toughness and resistance to fracture.

I understand that finding data for Aluminium can be challenging, but there are some resources available that may help. The National Institute of Standards and Technology (NIST) has a database of material properties that includes Charpy and Izod values for various materials, including Aluminium. You can also try reaching out to material suppliers or manufacturers, as they may have data on specific materials and alloys.

It is important to keep in mind that the results of impact tests can vary depending on the test setup and conditions, as you mentioned. Therefore, it may be best to use a combination of different impact test results, such as Charpy or Izod energies and Kic values, to get a better understanding of a material's performance under impact.

I hope this helps and good luck with your research!
 

Related to Low velocity impact of composites

What is low velocity impact of composites?

Low velocity impact of composites refers to the study of how composite materials, which are made up of two or more distinct materials combined together, behave when subjected to low energy impacts. This can include understanding the damage mechanisms, failure modes, and overall performance of the composite material.

Why is understanding low velocity impact of composites important?

Understanding low velocity impact of composites is important because composite materials are being increasingly used in various industries, such as aerospace, automotive, and sports, due to their high strength-to-weight ratio. Therefore, understanding how these materials behave under different loading conditions, such as low velocity impacts, is crucial for ensuring their safety and reliability.

What factors affect the low velocity impact performance of composites?

Several factors can affect the low velocity impact performance of composites, including the type and properties of the constituent materials, the layup orientation of the composite, the shape and size of the impactor, and the impact energy level. Environmental factors, such as temperature and humidity, can also play a role in the performance of composites under low velocity impact loading.

How is low velocity impact of composites studied?

Low velocity impact of composites is typically studied through experimental testing, numerical simulations, or a combination of both. Experimental testing involves subjecting composite specimens to low velocity impacts and measuring the resulting damage and deformation. Numerical simulations use computer models to predict the behavior of composites under low velocity impacts. Both approaches can provide valuable insights into the performance of composite materials.

What are some potential applications of the research on low velocity impact of composites?

The research on low velocity impact of composites has various potential applications, including improving the design and performance of composite structures in different industries, developing new materials and manufacturing processes, and enhancing the safety and durability of composite products. The findings from this research can also be used to create guidelines and standards for the use of composites in specific applications.

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