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Mechanics of Materials

Stress State: Dive into the World of Forces and Stresses!

Are you ready for an exciting journey into the world of physics? Then buckle up and discover the secrets of the stress state with us!

What is stress? Imagine you are building a giant Lego structure. The individual blocks push and pull against each other - that's exactly what stress is! In this course, you will learn how to calculate and understand these forces.

Stress components: Break down stress into its individual parts and discover how they interact. Just as a puzzle consists of many pieces, stress is also made up of different components.

Calculation: Crack the code of stress calculation! With a few clever formulas and tools, you can determine the forces in any component.

Transformation: Stresses change depending on the perspective. Learn how to transform them into different cutting planes and thus make the whole story of the load in the component visible.

Maximum stresses: Where does the greatest danger lurk? Find out where the stresses are highest in the component and how you can minimize them.

Mohr's circle of stress: This ingenious tool helps you to visualize stresses and to grasp important information at a glance.

Discover the fascination of the stress state! In this course you will not only learn dry knowledge, but also immerse yourself in the world of engineering. With good explanations and exciting application examples, the stress state becomes child's play.

Together we are strong! We will accompany you on your journey and help you to understand the complex concepts of the stress state. With our support you will master every challenge and become an expert for stable constructions.

So what are you waiting for? Start your journey into the world of stress now!

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1.1 Stress Vector

Stress is not always exciting

Okay, okay, let's be honest, stress is not always as thrilling as in the movies. In reality, stress is far from evenly distributed. Imagine you are pressing on a piece of clay. The stress at the point where you press is obviously highest. But what about the edges? It's a completely different story there.

Therefore, it is simply not enough to calculate the average stress. Such a value tells you nothing about what it looks like at a specific point.

Breaking down stress – small areas, big impact

So let's grab a microscope and zoom in. We divide the area into many tiny subareas – so small that we can barely see them. A small force then acts on each of these tiny areas.

Now we can calculate the stress for each individual area element. And if we add up all these small stresses, we get a pretty accurate picture of the stress distribution in the entire area.

The stress vector – stress has direction and magnitude

But wait a minute, there's something missing! Stress doesn't just have a magnitude, it also has a direction. In which direction does the force push?

That's exactly what the stress vector is for. It describes the stress at a specific point with magnitude and direction. It's like the sheriff in the wild west of stress.

Formula fun – for the brave

Okay, okay, I know, formulas aren't everyone's cup of tea. But for the brave among you, here is the formula for the stress vector:

$$ \begin{aligned} \vec{t} = \displaystyle \lim_{\Delta A \to 0} \dfrac{\Delta \vec{F}}{\Delta A} = \dfrac{d \vec{F}}{dA} \end{aligned} $$

(1.1)

Don't worry, it's not as bad as it looks.

Table – everything important at a glance
Symbol Description
\(\vec{t}\) (mechanical) Stress vector
\(\Delta \vec{F}\) Partial shear force transmitted in the surface element \(\Delta A\)
\(\Delta A\) Surface element
Stress vector – the hidden hero

Okay, admittedly, the stress vector isn't the most exciting guy in the universe. But it's incredibly important for understanding how components work and how they can fail.

So, next time you see a building or a machine, remember: the stress vector is the invisible hero that holds it all together.

This Figure 1.1.2 shows a general stress vector and its components.
Fig. 1.1.2: The stress vector and its components
Eyes on and participate, now it's getting exciting!