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  • Hi,guys,

    各位路人甲乙丙丁大家好

  • In this episode, let's talk about the relationship between the force and objects ,

    這集我們談力量與物體之間的關係

  • first this blue is an object,

    首先藍色這個是物體

  • it has contains both are convex and concave,

    它有包含了凸面和凹面

  • and also relatively wider and narrower parts,

    還有比較寬廣和狹窄的部分

  • when after the concept of the objects enters, we will to produce the proportional scale,

    當物體的概念進入後,我們會產生比例尺

  • the unit is what that not the focus,

    單位是什麼並非重點

  • this an object is subjected to variety of different roles by the forces and moment couple now,

    現在這個物體受到各種不同的力和力偶矩的作用

  • so it produced a certain the deformation,

    所以它產生了一定的變形

  • and the dashed line is the object line after it's deformed,

    而虛線就是它變形後的輪廓線

  • maybe it still will start to moves or rotations after thrust surface,

    也許它受力之後還會開始移動或轉動

  • the force will causes objects the moves dip direction,

    力量會使物體移動傾向...

  • the moment couple will causes objects to have rotates dip direction,

    力偶矩則使物體產生轉動傾向

  • the soil mechanics did not use to the moment couple,

    土壤力學並沒有用到力偶矩

  • so it will not appear again after this episode appears.

    所以在這集出現後就不再出現

  • that, we consider of the objects are also not rotation occurs ,

    而我們考慮的物體也都不會發生轉動

  • because the soil will not rotation,

    因土壤不會轉動

  • ok, next let's take a look at the force.

    好接下來我們來看一下力量

  • first, we can see it withstand the concentrated force of F1

    首先我們可以看到它承受F1的集中力

  • and the force of F2

    和F2的力量

  • there are also f1 and f2

    另外有f1和f2

  • the uniform force and distributed force,

    均佈力和分佈力

  • that, let's explain the nouns now,

    那現在我們來作名詞解釋

  • focusing on role by the object on 1 point is called the concentrated force,

    集中於物體1點上作用者稱作集中力

  • the concentrated force can act on or outside the objects,

    集中力可作用於物體上或物體之外

  • can be understood as the force at a distance, (but actually is vector movement), that's no problem,

    可以當作超距力理解(但其實是向量移動),並無問題

  • the force of unit we use is Newton N,

    力量我們使用的單位是牛頓N

  • the concentrated force actually is abstract concept,

    集中力其實是抽象概念

  • assume the force acts on a certain particle,

    假定了力量作用在某一質點

  • this particle doesn't exist in the real world,

    此質點在現實世界中並不存在

  • the force of real world must be demonstrated in the distributed force manner,

    現實世界的力量一定是以分佈力的方式去展現

  • even if you poke the potato with one needle,

    哪怕你用一根針戳馬鈴薯

  • the tip also has certain area,

    針尖也是有一定的面積

  • next, let's look at the distributed force,

    接下來我們來看分佈力

  • the distributed force can be called uniformity force in certain case,

    分佈力在某個情況下可以稱作均佈力

  • that is, it the same with role of "density"form on a certain acreage,

    就是它在一定面積上作用的"密度"是一樣的

  • that used here was is similar to the concept of density,

    這裡使用的是類似於密度的概念

  • the distributed force unit actually is how many Newtons is acts on per square meter,

    分佈力單位其實是每平方公尺上面作用多少牛頓

  • actually also is mean the how many Newtons is acts on each unit area,

    其實也是每單位面積上作用多少牛頓的意思

  • in fact, the distribution force can be equivalent to the concentrated force,

    其實分佈力可以等效於集中力

  • the equivalent manner is as follows:

    等效方式如下:

  • first to consider this the uniform force ,

    先考慮此均佈力

  • the density of the uniform force is f2

    均佈力的密度是f2

  • the interaction length is l2,

    作用長度為l2

  • what is the equivalent concentrated force of such a force?

    如此的等效集中力是多少呢?

  • write the concentrated force as the red arrow,

    集中力寫成紅色箭頭

  • it's value = f2 * l2

    其值=f2*l2

  • then multiply the unit area is 1

    再乘上單位面積是1

  • this 1 can be as length of paper surface prominence,

    這個1可以當作突出紙面的長度

  • we use angle of the three dimension to see is so

    我們用三維的角度來看就是如此

  • so it acts on an area,

    所以它作用於一面積上

  • the magnitude by the concentrated force is the volume of the rectangular parallelopiped,

    集中力大小就是長方體體積

  • i.e f2*l2*1

    即f2*l2*1

  • where is such a the concentrated force acting?

    那這樣的集中力作用在哪裡呢?

  • acting on above the centroid of the rectangle,

    作用在長方型的形心上面

  • the centroid is in the middle...so we draw the concentrated force right here,

    形心在中間...所以我們把集中力畫在這裡

  • point of application in about 1/2l2 the place,

    作用點在大約1/2l2的地方

  • another one distributed force is the triangle,

    另外一個分佈力是三角形

  • in fact, the distributed force can have any shape,

    其實分佈力可以有任何形狀

  • the triangle...that accordance with the rectangle,

    三角形...就比照長方形

  • the magnitude is the bottom multiplied by the height divided by two

    大小就是底乘以高除以二

  • point of application in 1/3l1 the place,

    作用點位置在1/3l1的地方

  • when in the exam, we used to take the uniform force

    在考試的時候我們習慣把均佈力

  • to calculates after change to the concentrated force,

    改成集中力後再來計算

  • because for the objects ,them are equivalent ,

    因為它們對物體來說是等效的

  • the so-called the equivalent is the same with the effect of generated,

    所謂等效就是產生的效應是一樣的

  • that let's consider a question now.

    那我們現在來考慮一個問題

  • what happens after an object is cuts ?

    將物體切開以後會發生什麼事?

  • we know the object is for the maintain its shape before the thrust surface,

    我們知道物體為了維持自己受力前的形狀

  • when subjected to external forces, internal forces are also will generated within the object,

    當受外力的時候,物體內部也會產生內力

  • so soil mechanics is defined...

    所以力學就是定義了...

  • the force that can be observed before cutting is the external force

    切開前可觀察的力為外力

  • the force that emerges after being cut is called the internal force.

    切開後才顯現的力量叫作內力

  • the internal force is actually very complicated,

    內力其實非常的複雜

  • and with the angle or way you cut,

    而且隨著你切開的角度或方式

  • the internal forces generated both are also different,

    所產生的內力也都不一樣

  • the internal forces must have appeard with form of distributed forces,

    內力一定是以分佈力的形式出現

  • it main can be divided into two types,

    它主要可以分作兩種

  • one is the normal stress and one is the tangential stress,

    一種是正向應力,一種是剪應力

  • the so-called the normal stress is the direction of stress vertical to the section,

    所謂正向應力就是應力方向垂直於切面

  • the so-called the tangential stress is the direction of stress parallel to the section,

    所謂剪應力就是應力方向平行於切面

  • such as red arrows

    如紅色的箭頭

  • the external force and internal force are gives to objects...

    那外力和內力對於物體...

  • effects produced are not the same,

    產生的效應並不一樣

  • what's the effects produced of the external force?

    外力產生的效應是什麼呢?

  • has movement, rotation, reaction force, work and so on ...

    有移動、轉動、反作用力、作功...等等

  • for the internal force, it will make the...

    內力來說的話,它會使的...

  • the stress in the object changes,

    物體裡面的應力產生變化

  • deformation, transformation energy...and so on.

    變形、能量變化...等等

  • for in soil mechanics...

    在土壤力學來說...

  • when the external force continue to increase in the case, the internal force will rise accordingly,

    外力不斷增加的情況下,內力也會相應上升

  • the normal stress in the soils will causes soil consolidation,

    土壤內的正向應力會使的土壤壓密

  • that is the density increases (strength rises),

    也就是密度增加(強度上升)

  • the increase of the tangential stress will make the the general shear failure of soils,

    剪應力的上升則會使土壤剪力破壞

  • the main form of soil damage is the general shear failure,

    土壤主要的破壞形式就是剪力破壞

  • finally, let's supplement the concept of "the rigid body",

    最後我們來補充「剛體」的概念

  • the rigid body is considered as the ideal objects for the internal effects are not exist.

    剛體視為內效應不存在之理想物體

  • can imagine the rigid body don't exist in the real world,

    可以想見剛體並不存在於現實世界中

  • within the subjects of engineering mechanics is

    在工程力學的科目裡面

  • the objects are all assumed be the rigid bodies,,

    物體都被假設為剛體

  • that is, only the effects of external and external effects are considered,

    也就是只考慮外力和外效應的影響

  • the material mechanics will considered of internal force the part,

    而材料力學則會考慮內力的部分

  • then the soil mechanics is builted on top of these two subjects,

    土壤力學又建立在二科之上

  • so the scope of consideration is will again broader,

    所以考慮的面向又更廣了

  • ok, the above is all the content today. Bye ~

    以上就是今天全部的內容~~掰掰~~

Hi,guys,

各位路人甲乙丙丁大家好

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B1 中級 中文 美國腔 物體 土壤 力學 作用 產生 面積

土壤力學 (Soil mechanics)

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    WC 發佈於 2021 年 01 月 14 日
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