標題: 變形、位移和撓度之間的區別 [打印本頁] 作者: 獨自莫憑欄 時間: 2015-7-23 10:51 標題: 變形、位移和撓度之間的區別 在社區中看到有人發帖問變形量與撓度是不是一樣,仔細一想,自己還真不是很清楚這幾個概念之間的區別。請大家說說對這幾個基礎概念的理解。 ( \- `" |& l4 q% `作者: 獨自莫憑欄 時間: 2015-7-23 10:52
我先來貼一個國外工程師的理解: 7 f% d* D6 ^1 K0 G! s5 m1 H- IIsaac Gaetz, Structural Engineer- c4 \$ G7 ^" C! d5 i! u A* J4 k
Isaac has 210+ answers and 13 endorsements in Civil Engineering." a0 _3 W ^ B/ w( W$ s2 R
In the field of structural engineering these are closely related terms, and sometimes used interchangeably, though if you want to get specific there are cases where one term is more appropriate than another./ n7 @- x' q% E/ n; P4 @; ]& b
% }' G3 L) m c, W0 @3 RThese are how I understand the terms, though I'll be curious to see if anyone disagrees. " E# h" K* h& L. y, ?! f" L5 ^) E6 p! V5 G |5 l- C J
Displacement is the distance from which one node or element (beam, column, frame, etc) moved from its original location. The movement could be from a beam deflecting, but it could also be the result of the entire object moving, un-distorted, like a box sliding on a surface with friction. Displacement can both be measured in terms of distance and in terms of rotation., L. G9 M9 V5 M
$ U2 x7 f% v% h5 t6 e+ H+ @Deflection is the distance that an object bends, twists from its original position. I would generally assume that an objects deflection does not include rigid movement of the object.+ j! g, u; @6 D
7 a: S7 X7 s( V, z! T% @Deformation is the actual distortion that occurs to a structural member. We most commonly discuss elastic and plastic deformations. Elastic deformations are those deformations that, when the loading is removed, will return to the original undeflected shape. Plastic deformations are those that will remain even after the loading is removed. % W& M9 j' H2 E; q- c3 }5 v, T0 i. | 0 c' R X# {8 f8 NBecause most structures are securely attached to their foundation, there is general no rigid body motion, and displacement and deflection are particular similar concepts. I would say the outlier is deformations. Displacements and Deflections are generally measures of distance (or ratios of that distance compared to a meaningful value, such as the member length) while deformation is what happened to the member to cause the displacements/deflections. ) _: b# b3 J5 \- |+ m供大家討論。作者: 愛貓人士薛定諤 時間: 2015-7-23 11:16
我的理解:, ?0 I/ t1 f, D" y4 @& A
變形:物體發生形狀改變(外力或受熱等),所發生幾何尺寸在某個方向或度量上的改變( S3 `0 x5 h: V8 D( e5 X
位移:物體或物體上的某一點,在某個坐標系統下發生坐標變化,連接首尾位置的向量的長度值7 d0 O3 x# _" J& Y# R) h' D
繞度:梁變形(受熱等),形心相對于原位置的法向變動量作者: 寂靜天花板 時間: 2015-7-23 11:19 本帖最后由 寂靜天花板 于 2015-7-23 11:21 編輯 - E- \* K1 I& q/ |; s
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撓度的概念很清晰,是桿件變形專用。 : G9 U- b/ v, L+ e+ f# @! z[attach]360143[/attach]) d1 a; Y) L5 t, y- M) |
而變形與位移的概念也很清楚1 p1 }4 c% F; _: {' ^0 _4 z
[attach]360144[/attach]作者: biudiu 時間: 2015-7-23 11:41
大俠,書上都有的,翻翻書挺好的 8 j |! \, q0 O# E5 {: o8 A書上的總結是前人經過總結和思考的,咱們再談,談著談著就容易跑偏了 : l8 u! d% c- P" p9 E$ J3 a5 T1 k8 z' A
樓上大俠嚴謹的態度,值得學習作者: 獨自莫憑欄 時間: 2015-7-23 12:36
又查了資料,談一下自己的理解。 9 w3 a+ C% R" X第一、變形量這個可以指材料本身的變形,也可以指構件的變形; G: G, G x' b4 w9 g7 r
第二、撓度只用于描述桿與梁類構件帶載時的質點位移量。 & e i+ ~0 |% T; U) w舉個例子,如果有一根懸臂梁,我們在伸出的一端施加一個載荷,其撓度可能是1cm,而該懸臂梁的材料狀態為,上表面為拉伸狀態,下表面為壓縮狀態,其材料的變形量可能才是0.01mm。( V4 U D1 L9 J- `% T+ c" O
至于位移與撓度,是不是撓度只是在某個方向的位移呢?3 S0 H8 R8 @) {3 m3 b
請大家批評指正。作者: biudiu 時間: 2015-7-23 12:58