What is the Toughest Material? Carbon-Fiber Nano Tubes & Brittle Materials

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Discussion Overview

The discussion centers around the concept of toughness in materials, specifically exploring which material can be considered the "toughest." Participants examine definitions of toughness, the classification of carbon-fiber nanotubes, and the comparison between brittle and ductile materials.

Discussion Character

  • Debate/contested

Main Points Raised

  • Some participants define toughness as the area under the curve of a stress-strain diagram, suggesting that it reflects both ultimate strength and the ability to strain before breaking.
  • One participant nominates steel as the toughest material based on an Ashby chart of toughness.
  • Another participant states that toughness is the specific amount of energy a material can absorb before failure and questions the classification of carbon-fiber nanotubes due to manufacturing limitations.
  • There is a claim that brittle materials are usually not as tough as ductile ones, with a participant suggesting Kevlar as a potential tough material.
  • A later reply challenges the Kevlar nomination by referencing TRIP steels with high fracture toughness values, questioning which Kevlar composite could exceed this.

Areas of Agreement / Disagreement

Participants express differing views on the toughest material, with some supporting steel and others suggesting Kevlar or questioning the classification of carbon-fiber nanotubes. The discussion remains unresolved regarding the toughest material and the toughness of brittle versus ductile materials.

Contextual Notes

Participants rely on specific definitions and charts, such as the Ashby chart, which may not be universally accepted. The discussion also highlights the limitations in the current manufacturing capabilities of carbon-fiber nanotubes.

jmarcian
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"toughest" material

by terms of "mechanics" (physics, not the ones that work on your car). toughness is shown as the area under the curve of a stress strain diagram. from the we can say that this material offers a high ultimate strength, but also can strain a fair amount before breaking...
with that definition, what would you say the "toughest" material is?

also, would carbon-fiber nano tubes be considered brittle or ductile?

also, can brittle materials be as tough as ductile ones?


thanks
jared
 
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I'll nominate steel for toughest material (based on an Ashby chart of toughness).
 


Toughness is basically the specific amount of energy a material can absorb before it fails.

I don't think you can classify nano-tubes as either since we can't manufacturer them in a pure lattice form yet.

And no, brittle materials are usually not as tough as ductile ones.
Mapes said:
I'll nominate steel for toughest material (based on an Ashby chart of toughness).

I seriously doubt that.

If I had to guess I would say Kevlar.
 


Why guess? TRIP steels have a KIC exceeding 200 MPa-m1/2. Which Kevlar composite exceeds this?
 

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