# Understanding Material Breakage: Fractures, Fatigue, and More

• anime9999
In summary: It involves understanding the behavior of materials under stress and how cracks and fractures form. There is also a concept of fatigue, which describes how repeated loading can cause a material to fail even if the load is not very high. Essentially, each hit or stress affects the structure of the material, and with enough hits or stress, a fracture can occur. However, predicting when and how fractures will occur is a complicated process and is the focus of the field of fracture mechanics. In summary, fractures, breaks, and fatigues occur due to repeated stress on a material, and understanding this process is a complex subject covered in the field of fracture mechanics.
anime9999
Hi and thank you in advance.

I want to understand how do fractures/breaks/fatigues occur in general.

I remember a proverb saying that when a farmer breaks a rock after 100 hits using his axe, it is not the 100th hit that breaks the rock, but it is all of the 100 hits.

How material break? what happens when you hit a metal with something and it doesn't break? where does the energy go? does every hit means a degradation in the structure (although not visible)?

For example, if I gently hit my tooth with a spoon, do I still impact the structure of my tooth (although my tooth doesn't break?)

I hope you understand my question.
Thank you and best regards.

You should look up fatigue. Find an article with an S-N curve if you can.

What you are describing is an entire academic field called Fracture Mechanics, covered by many engineering courses. The field is vast, and the process of fracture will depend on the material, loading and test conditions, etc.

Start with this link, and there are also numerous books and papers on the subject depending on what materials you are interested in:

http://en.wikipedia.org/wiki/Fracture_mechanics

Thank you. I will look up fatigue and fracture mechanics.
I see this is indeed a very complex subject.

I can provide some insights into understanding material breakage, fractures, and fatigue. Material breakage occurs when the applied stress on a material exceeds its strength, causing it to fail. This can happen through various mechanisms such as fractures, fatigue, and plastic deformation.

Fractures occur when the material experiences an external force that exceeds its strength, causing it to crack or break. This can happen due to a single large force or repeated smaller forces over time.

Fatigue, on the other hand, is the weakening of a material due to repeated loading and unloading cycles. This can happen even when the forces applied are below the material's strength, as the cumulative effect of the repeated cycles can cause microcracks to form and grow, eventually leading to failure.

In your example of the farmer breaking a rock with his axe, it is not just the 100th hit that causes the rock to break. Each hit weakens the rock, causing microcracks to form and grow until it can no longer withstand the applied force.

When hitting a metal with something, the energy from the impact is transferred to the material. If the force is below the material's strength, it will deform elastically and return to its original shape. However, if the force is above the material's strength, it will deform plastically, causing permanent damage and potentially leading to failure.

In the case of your tooth and spoon example, hitting your tooth with a spoon may not cause visible damage, but it can still impact the structure of your tooth at a microscopic level. The repeated impacts over time can lead to fatigue and weaken the tooth, making it more prone to fractures or breaks in the future.

I hope this helps to answer your question and provide a better understanding of material breakage. It is important to consider the strength and fatigue properties of materials when designing and using them in various applications to prevent failures and ensure their longevity. Thank you for your question and best regards.

## 1. What causes material fractures?

Material fractures can be caused by a variety of factors, including excessive stress or strain, impact or shock loading, temperature changes, corrosion, and manufacturing defects. It is important to understand the specific cause of a fracture in order to prevent future occurrences.

## 2. What is fatigue failure?

Fatigue failure occurs when a material breaks after being subjected to repeated loading and unloading cycles. This type of failure is common in materials that are constantly under stress, such as in machinery or structural components. It can also be caused by exposure to harsh environmental conditions.

## 3. How can material fractures be prevented?

Material fractures can be prevented by using high-quality materials, properly designing and manufacturing components, and conducting thorough inspections and maintenance. It is also important to consider potential stressors and environmental factors that may impact the material's integrity.

## 4. What is the difference between ductile and brittle fracture?

Ductile fractures occur when a material deforms before breaking, while brittle fractures happen suddenly and without significant deformation. Ductile fractures are typically caused by tensile stress, while brittle fractures can occur under tension, compression, or shear stress. Understanding the type of fracture is important for determining the cause and preventing future failures.

## 5. How is material breakage studied and analyzed?

Material breakage is studied through a combination of experimental testing and computer simulations. These methods can help determine the effects of different stressors and identify potential failure points. Material analysis techniques, such as fractography, can also provide insight into the cause of a fracture.

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