Funny! Pictures and texts give you a comprehensive understanding of the effects of dynamics and mass

Xiaobian is currently working for a company that provides cloud simulation software （ Remote computing technology ）, Although this form of software product is very convenient , The price is very low , However, the industry is not very familiar with , Therefore, it is often necessary to contact manufacturing enterprises …… So I have to take the high-speed rail often ……

From then on , I began to have some strange ideas , And I think of a question I thought about when I was a child ……

If I jump up on the roof of a moving train like Jackie Chan , Then the train will continue , Will I fall down ？

What if I decide to jump ？

When I'm in the air , Will the train continue to pass under my feet , Will I fall ？

After the physics class, I know I can't , Because of the influence of inertia , My speed is the same as that of a train ：

however , I ignored the wind on the roof ...

So here comes the question ....

Why sometimes I still feel the train running ？

For example, when the train just started ？

Be careful ： Xiao Bian never really tested my theory on the top of the train …… So please don't try what I'm describing here （ Except Jackie Chan ~）

Okay , Back to the problem …… How to explain acceleration “ Feeling ”？

Let me explain

You actually feel the acceleration of the train

When the train goes from 0 At the beginning of the speed , It must accelerate to a certain speed

When the acceleration is positive , Speed up , Then when the required speed is reached , The acceleration is zero , The speed becomes constant

Why do I feel acceleration instead of velocity ？

The acceleration is basically the difference in velocity , But combined with quality , Is equal to force ：

This relationship shows that , The acceleration is basically pulling the mass , And the resulting force is proportional to it

Here are two things to note ：

l Greater mass produces greater power

l Inertia is a dynamic phenomenon , It will cause a sudden force to enter the object with a rapidly changing acceleration

When the speed increases , It does not rise immediately where it takes time to spread …… That's why in a very short time , I feel the acceleration , Then I can't feel it ……

Imagine , The train moves the ground first , Pull foot , Then fix your feet on your body , Velocity waves travel through the body

Now you know what the combination of mass and acceleration does ……

You may want to know why FEA in , We usually don't care about quality at all ……（ Linear static analysis requires only young's modulus and Poisson's ratio ）

stay FEA in , Is quality always important ？

As you can see here , Static means time independent , therefore , The sum of all the forces is 0....

therefore , Subtract the mass from the formula , There is no need to think about ....

This is why in finite element analysis , We only care about the quality under dynamic conditions ... That is, when inertia and mass really work

perhaps … When we consider gravity , Of course （Fg=m.g） This is a statically loaded core

Now we have this beautiful abstract theory , Maybe what you want to know is ：

“ When can you really apply this kind of thing to finite element analysis ？”

Um. .. You may know , If you pay attention to this knowledge for a period of time , Visited some forums , Take a look at our homepage , There are many types of finite element analysis .

Linear static analysis is obviously the simplest and most direct analysis

But it comes with some constraints , For example, the boundary condition has a fixed direction and value , And is thought to act on objects infinitely and slowly , For example, in elastic deformation

Ran goose , You know the reality may be different

actually , I've been thinking , In reality , What would it be to apply the load in an infinitely slow manner ....

It looks like a cartoon character in the air 30 minute , And then you really hit the ground ...

…… By the way …

When I think of it … The damage caused by the punch is caused by the combination of inertia and speed

in fact , Some loads are applied too fast , If you look at their time curves … You will get the result ：

Can you think that such a load is imposed infinitely slowly …？？？

Of course not. …

At this point, you need to use more advanced analysis , for example ：

Linear transient analysis or nonlinear transient analysis （ If considering the impact …）

（ Yes , You can mix nonlinear and dynamic behavior to analyze very short time events … This kind of analysis is a high-level product . Want to know how to analyze , Leave a message in the comments