vault backup: 2025-07-31 09:47:18
This commit is contained in:
parent
0726d19446
commit
7bd9d92473
@ -33,5 +33,5 @@ curl -X PUT "http://localhost:50003/proxies/%F0%9F%9A%80%E4%BB%A3%E7%90%86%E7%BA
|
||||
https://aistudio.google.com/u/1/apikey
|
||||
|
||||
|
||||
|
||||
https://aistudio.google.com/apikey
|
||||
|
||||
|
@ -0,0 +1,196 @@
|
||||
---
|
||||
epoch: 1753754856981
|
||||
modelKey: gemini-2.5-pro|google
|
||||
tags:
|
||||
- copilot-conversation
|
||||
---
|
||||
|
||||
**user**:
|
||||
$$
|
||||
\sum_{j=1}^{N_{D}}m_{i j}\ddot{q}_{j}+\sum_{j=1}^{N_{D}}g_{i j}\dot{q}_{j}+F_{c,i}+\sum_{j=1}^{N_{D}}\sum_{k=1}^{N_{D}}h_{i j k}\dot{q}_{j}\dot{q}_{k}+\frac{\partial V}{\partial q_{i}}+\frac{\partial D}{\partial\dot{q}_{i}}=Q_{i}\tag{1.7}
|
||||
$$
|
||||
如何由
|
||||
Substituting (1.4) into (1.3) and using the properties of (1.5) and (1.6), the nonlinear equations of motion can be written as
|
||||
推导得到
|
||||
[Timestamp: 2025/07/29 10:07:36]
|
||||
|
||||
**ai**: 您好,为了从您提到的 “将 (1.4) 代入 (1.3) 并使用 (1.5) 和 (1.6) 的性质” 来推导方程 (1.7),我需要知道方程 (1.3), (1.4), (1.5), 和 (1.6) 的具体形式。
|
||||
|
||||
不过,我可以根据方程 (1.7) 的结构,为您提供一个一般性的推导思路。这个方程是典型的拉格朗日力学(Lagrangian Mechanics)在有约束和非保守力情况下的运动方程形式。
|
||||
|
||||
**一般推导步骤**
|
||||
|
||||
通常,这类方程的推导始于**拉格朗日方程**。
|
||||
|
||||
1. **起点:拉格朗日方程 (可能是您的方程 1.3)**
|
||||
标准的第二类拉格朗日方程形式为:
|
||||
$\frac{d}{dt}\left(\frac{\partial L}{\partial \dot{q}_{i}}\right) - \frac{\partial L}{\partial q_{i}} = Q_{i}^{nc}$
|
||||
其中,$L = T - V$ 是拉格朗日量,$T$ 是系统的动能,$V$ 是系统的势能。$q_i$ 是广义坐标,$\dot{q}_i$ 是广义速度。$Q_{i}^{nc}$ 是作用在 $q_i$ 上的非保守广义力。
|
||||
|
||||
2. **动能表达式 (可能是您的方程 1.4)**
|
||||
对于一个多体系统,动能 $T$ 通常是广义速度的二次型函数:
|
||||
$T = \frac{1}{2}\sum_{j=1}^{N_{D}}\sum_{k=1}^{N_{D}}m_{jk}(q)\dot{q}_{j}\dot{q}_{k}$
|
||||
这里的 $m_{jk}(q)$ 是对称的质量矩阵(或惯性张量),其元素通常是广义坐标 $q$ 的函数。
|
||||
|
||||
3. **代入拉格朗日方程**
|
||||
我们将 $L = T - V$ 代入拉格朗日方程。
|
||||
* 首先计算 $\frac{\partial L}{\partial \dot{q}_{i}}$:
|
||||
$\frac{\partial L}{\partial \dot{q}_{i}} = \frac{\partial T}{\partial \dot{q}_{i}} = \frac{\partial}{\partial \dot{q}_{i}}\left(\frac{1}{2}\sum_{j,k}m_{jk}\dot{q}_{j}\dot{q}_{k}\right) = \sum_{j=1}^{N_{D}}m_{ij}\dot{q}_{j}$
|
||||
* 然后对时间求全导数 $\frac{d}{dt}$:
|
||||
$\frac{d}{dt}\left(\frac{\partial L}{\partial \dot{q}_{i}}\right) = \frac{d}{dt}\left(\sum_{j}m_{ij}\dot{q}_{j}\right) = \sum_{j}m_{ij}\ddot{q}_{j} + \sum_{j}\frac{dm_{ij}}{dt}\dot{q}_{j}$
|
||||
因为 $m_{ij}$ 是 $q$ 的函数,所以 $\frac{dm_{ij}}{dt} = \sum_{k}\frac{\partial m_{ij}}{\partial q_{k}}\dot{q}_{k}$。代入上式得到:
|
||||
$\frac{d}{dt}\left(\frac{\partial L}{\partial \dot{q}_{i}}\right) = \sum_{j}m_{ij}\ddot{q}_{j} + \sum_{j,k}\frac{\partial m_{ij}}{\partial q_{k}}\dot{q}_{j}\dot{q}_{k}$
|
||||
* 接着计算 $\frac{\partial L}{\partial q_{i}}$:
|
||||
$\frac{\partial L}{\partial q_{i}} = \frac{\partial T}{\partial q_{i}} - \frac{\partial V}{\partial q_{i}} = \frac{1}{2}\sum_{j,k}\frac{\partial m_{jk}}{\partial q_{i}}\dot{q}_{j}\dot{q}_{k} - \frac{\partial V}{\partial q_{i}}$
|
||||
|
||||
4. **整理方程**
|
||||
将以上各项代入拉格朗日方程:
|
||||
$\left(\sum_{j}m_{ij}\ddot{q}_{j} + \sum_{j,k}\frac{\partial m_{ij}}{\partial q_{k}}\dot{q}_{j}\dot{q}_{k}\right) - \left(\frac{1}{2}\sum_{j,k}\frac{\partial m_{jk}}{\partial q_{i}}\dot{q}_{j}\dot{q}_{k} - \frac{\partial V}{\partial q_{i}}\right) = Q_{i}^{nc}$
|
||||
整理后得到:
|
||||
$\sum_{j}m_{ij}\ddot{q}_{j} + \sum_{j,k}\left(\frac{\partial m_{ij}}{\partial q_{k}} - \frac{1}{2}\frac{\partial m_{jk}}{\partial q_{i}}\right)\dot{q}_{j}\dot{q}_{k} + \frac{\partial V}{\partial q_{i}} = Q_{i}^{nc}$
|
||||
|
||||
5. **引入 Christoffel 符号 (可能是您的方程 1.5 和 1.6)**
|
||||
为了得到您给出的方程 (1.7) 的形式,通常会引入与**克氏符号 (Christoffel symbols)** 相关的项。与科里奥利力(Coriolis force)和离心力(centrifugal force)相关的项可以表示为:
|
||||
$\sum_{j,k}h_{ijk}\dot{q}_{j}\dot{q}_{k}$
|
||||
其中 $h_{ijk}$ (有时也写作 $\Gamma_{ijk}$) 是与质量矩阵导数相关的克氏符号,定义为:
|
||||
$h_{ijk} = \frac{1}{2}\left(\frac{\partial m_{ij}}{\partial q_{k}} + \frac{\partial m_{ik}}{\partial q_{j}} - \frac{\partial m_{jk}}{\partial q_{i}}\right)$
|
||||
通过这个定义,可以将上面整理出的方程中的二次速度项进行重写。这部分通常就是利用您提到的 (1.5) 和 (1.6) 的性质来完成的,它们可能定义了 $h_{ijk}$ 和 $g_{ij}$。
|
||||
|
||||
6. **包含其他力**
|
||||
方程 (1.7) 中的其他项代表了不同的力:
|
||||
* $F_{c,i}$: 可能是约束力(Constraint Force)。
|
||||
* $\frac{\partial D}{\partial\dot{q}_{i}}$: 来自瑞利耗散函数(Rayleigh dissipation function)$D$ 的耗散力。
|
||||
* $Q_i$: 外部施加的广义力。
|
||||
这些力都属于非保守广义力 $Q_{i}^{nc}$ 的一部分。
|
||||
|
||||
**总结**
|
||||
|
||||
您的方程 (1.7) 是一个非常通用的动力学方程。其推导的核心是将系统的动能表达式 (1.4) 代入拉格朗日方程 (1.3),然后利用质量矩阵导数的性质 (1.5) 和 (1.6) 来定义和简化科里奥利/离心力项 ($h_{ijk}$) 和可能的陀螺力项 ($g_{ij}$),最后将所有保守力(势能力)和非保守力(耗散力、约束力、外力)整合在一起。
|
||||
|
||||
如果您能提供方程 (1.3) 到 (1.6) 的内容,我可以为您展示一个完整且具体的推导过程。
|
||||
[Timestamp: 2025/07/29 10:08:11]
|
||||
|
||||
**user**: $$
|
||||
\sum_{j=1}^{N_{D}}\frac{\partial^{2}T}{\partial{\dot{q}}_{i}\partial{\dot{q}}_{j}}{\ddot{q}}_{j}+\sum_{j=1}^{N_{D}}\frac{\partial^{2}T}{\partial{\dot{q}}_{i}\partial q_{j}}{\dot{q}}_{j}+\frac{\partial}{\partial t}\bigg(\frac{\partial T}{\partial{\dot{q}}_{i}}\bigg)-\frac{\partial T}{\partial q_{i}}+\frac{\partial D}{\partial{\dot{q}}_{i}}+\frac{\partial V}{\partial q_{i}}=Q_{i}\tag{1.3}
|
||||
$$
|
||||
$$
|
||||
T=\int_{\mathcal{V}}\frac{1}{2}\;\rho\;\dot{\mathbf{r}}^{T}\dot{\mathbf{r}}\;d\mathcal{V}\tag{1.4}
|
||||
$$
|
||||
$$
|
||||
\dot{\pmb{r}}=\frac{d\pmb{r}}{d t}=\sum_{j=1}^{N_{D}}\frac{\partial\pmb{r}}{\partial q_{j}}\dot{q}_{j}+\frac{\partial\pmb{r}}{\partial t}\tag{1.5}
|
||||
$$
|
||||
$$
|
||||
{\frac{\partial{\dot{\mathbf{r}}}}{\partial{\dot{q}}_{i}}}={\frac{\partial\mathbf{r}}{\partial q_{i}}}\quad{\mathsf{a n d}}\quad{\frac{\partial^{2}{\dot{\mathbf{r}}}}{\partial{\dot{q}}_{i}\partial q_{j}}}={\frac{\partial\mathbf{r}}{\partial q_{i}\partial q_{j}}}={\frac{\partial^{2}{\dot{\mathbf{r}}}}{\partial q_{i}\partial{\dot{q}}_{j}}}\tag{1.6}
|
||||
$$
|
||||
[Timestamp: 2025/07/29 10:09:06]
|
||||
|
||||
**ai**: 好的,感谢您提供这些方程。这是一个非常经典的从分析力学基本原理推导多体系统动力学方程的过程。下面我将为您展示详细的推导步骤。
|
||||
|
||||
**目标**
|
||||
我们的目标是从方程 (1.3) 出发,利用 (1.4), (1.5), (1.6) 的定义,最终得到方程 (1.7) 的形式:
|
||||
$$
|
||||
\sum_{j=1}^{N_{D}}m_{i j}\ddot{q}_{j}+\sum_{j=1}^{N_{D}}g_{i j}\dot{q}_{j}+F_{c,i}+\sum_{j=1}^{N_{D}}\sum_{k=1}^{N_{D}}h_{i j k}\dot{q}_{j}\dot{q}_{k}+\frac{\partial V}{\partial q_{i}}+\frac{\partial D}{\partial\dot{q}_{i}}=Q_{i}\tag{1.7}
|
||||
$$
|
||||
|
||||
**核心思路**
|
||||
核心在于计算方程 (1.3) 中与动能 $T$ 相关的项。一个更简洁的方法是回到拉格朗日方程的原始形式 $\frac{d}{dt}(\frac{\partial T}{\partial \dot{q}_i}) - \frac{\partial T}{\partial q_i}$,并对其进行求值。方程 (1.3) 只是这个表达式按链式法则展开后的形式。
|
||||
|
||||
**步骤 1: 简化拉格朗日方程的动能部分**
|
||||
|
||||
我们先计算两个关键的偏导数:
|
||||
1. $\frac{\partial T}{\partial \dot{q}_i} = \frac{\partial}{\partial \dot{q}_i} \left( \int_{\mathcal{V}}\frac{1}{2}\;\rho\;\dot{\mathbf{r}}^{T}\dot{\mathbf{r}}\;d\mathcal{V} \right) = \int_{\mathcal{V}} \rho \;\dot{\mathbf{r}}^{T} \frac{\partial \dot{\mathbf{r}}}{\partial \dot{q}_i} \;d\mathcal{V}$
|
||||
根据方程 (1.6),我们有 ${\frac{\partial{\dot{\mathbf{r}}}}{\partial{\dot{q}}_{i}}}={\frac{\partial\mathbf{r}}{\partial q_{i}}}$。代入上式:
|
||||
$$
|
||||
\frac{\partial T}{\partial \dot{q}_i} = \int_{\mathcal{V}} \rho \;\dot{\mathbf{r}}^{T} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V}
|
||||
$$
|
||||
|
||||
2. $\frac{\partial T}{\partial q_i} = \frac{\partial}{\partial q_i} \left( \int_{\mathcal{V}}\frac{1}{2}\;\rho\;\dot{\mathbf{r}}^{T}\dot{\mathbf{r}}\;d\mathcal{V} \right) = \int_{\mathcal{V}} \rho \;\dot{\mathbf{r}}^{T} \frac{\partial \dot{\mathbf{r}}}{\partial q_i} \;d\mathcal{V}$
|
||||
|
||||
现在,我们计算 $\frac{\partial T}{\partial \dot{q}_i}$ 对时间的全导数:
|
||||
$$
|
||||
\frac{d}{dt}\left(\frac{\partial T}{\partial \dot{q}_i}\right) = \frac{d}{dt}\left( \int_{\mathcal{V}} \rho \;\dot{\mathbf{r}}^{T} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V} \right) = \int_{\mathcal{V}} \rho \left( \ddot{\mathbf{r}}^{T} \frac{\partial \mathbf{r}}{\partial q_i} + \dot{\mathbf{r}}^{T} \frac{d}{dt}\left(\frac{\partial \mathbf{r}}{\partial q_i}\right) \right) \;d\mathcal{V}
|
||||
$$
|
||||
利用导数交换次序的性质 $\frac{d}{dt}\left(\frac{\partial \mathbf{r}}{\partial q_i}\right) = \frac{\partial}{\partial q_i}\left(\frac{d\mathbf{r}}{dt}\right) = \frac{\partial \dot{\mathbf{r}}}{\partial q_i}$,我们得到:
|
||||
$$
|
||||
\frac{d}{dt}\left(\frac{\partial T}{\partial \dot{q}_i}\right) = \int_{\mathcal{V}} \rho \left( \ddot{\mathbf{r}}^{T} \frac{\partial \mathbf{r}}{\partial q_i} + \dot{\mathbf{r}}^{T} \frac{\partial \dot{\mathbf{r}}}{\partial q_i} \right) \;d\mathcal{V}
|
||||
$$
|
||||
将以上结果组合成拉格朗日算子:
|
||||
$$
|
||||
\frac{d}{dt}\left(\frac{\partial T}{\partial \dot{q}_i}\right) - \frac{\partial T}{\partial q_i} = \int_{\mathcal{V}} \rho \left( \ddot{\mathbf{r}}^{T} \frac{\partial \mathbf{r}}{\partial q_i} + \dot{\mathbf{r}}^{T} \frac{\partial \dot{\mathbf{r}}}{\partial q_i} \right) \;d\mathcal{V} - \int_{\mathcal{V}} \rho \;\dot{\mathbf{r}}^{T} \frac{\partial \dot{\mathbf{r}}}{\partial q_i} \;d\mathcal{V}
|
||||
$$
|
||||
可以看到,后面两项完全相同,相互抵消。于是我们得到了一个极为简洁的结果:
|
||||
$$
|
||||
\frac{d}{dt}\left(\frac{\partial T}{\partial \dot{q}_i}\right) - \frac{\partial T}{\partial q_i} = \int_{\mathcal{V}} \rho \;\ddot{\mathbf{r}}^{T} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V}
|
||||
$$
|
||||
这个结果等价于方程 (1.3) 中所有与 $T$ 相关的项的总和。
|
||||
|
||||
**步骤 2: 计算广义加速度 $\ddot{\mathbf{r}}$**
|
||||
|
||||
现在我们需要将笛卡尔加速度 $\ddot{\mathbf{r}}$ 用广义坐标 $q_j$ 及其导数来表示。我们从方程 (1.5) 开始,并对其求时间导数:
|
||||
$$
|
||||
\dot{\mathbf{r}}=\sum_{j=1}^{N_{D}}\frac{\partial\mathbf{r}}{\partial q_{j}}\dot{q}_{j}+\frac{\partial\mathbf{r}}{\partial t}
|
||||
$$
|
||||
$$
|
||||
\ddot{\mathbf{r}} = \frac{d\dot{\mathbf{r}}}{dt} = \frac{d}{dt} \left( \sum_{j=1}^{N_{D}}\frac{\partial\mathbf{r}}{\partial q_{j}}\dot{q}_{j}+\frac{\partial\mathbf{r}}{\partial t} \right)
|
||||
$$
|
||||
使用乘法法则和链式法则展开:
|
||||
$$
|
||||
\ddot{\mathbf{r}} = \sum_{j=1}^{N_{D}} \left( \frac{d}{dt}\left(\frac{\partial\mathbf{r}}{\partial q_{j}}\right) \dot{q}_{j} + \frac{\partial\mathbf{r}}{\partial q_{j}}\ddot{q}_{j} \right) + \frac{d}{dt}\left(\frac{\partial\mathbf{r}}{\partial t}\right)
|
||||
$$
|
||||
再次对全导数项使用链式法则:
|
||||
* $\frac{d}{dt}\left(\frac{\partial\mathbf{r}}{\partial q_{j}}\right) = \sum_{k=1}^{N_D} \frac{\partial^2\mathbf{r}}{\partial q_k \partial q_j}\dot{q}_k + \frac{\partial^2\mathbf{r}}{\partial t \partial q_j}$
|
||||
* $\frac{d}{dt}\left(\frac{\partial\mathbf{r}}{\partial t}\right) = \sum_{k=1}^{N_D} \frac{\partial^2\mathbf{r}}{\partial q_k \partial t}\dot{q}_k + \frac{\partial^2\mathbf{r}}{\partial t^2}$
|
||||
|
||||
将它们代回 $\ddot{\mathbf{r}}$ 的表达式中:
|
||||
$$
|
||||
\ddot{\mathbf{r}} = \sum_{j=1}^{N_{D}} \frac{\partial\mathbf{r}}{\partial q_{j}}\ddot{q}_{j} + \sum_{j=1}^{N_{D}} \left( \sum_{k=1}^{N_D} \frac{\partial^2\mathbf{r}}{\partial q_k \partial q_j}\dot{q}_k + \frac{\partial^2\mathbf{r}}{\partial t \partial q_j} \right) \dot{q}_{j} + \left( \sum_{k=1}^{N_D} \frac{\partial^2\mathbf{r}}{\partial q_k \partial t}\dot{q}_k + \frac{\partial^2\mathbf{r}}{\partial t^2} \right)
|
||||
$$
|
||||
整理并合并同类项:
|
||||
$$
|
||||
\ddot{\mathbf{r}} = \sum_{j=1}^{N_{D}} \frac{\partial\mathbf{r}}{\partial q_{j}}\ddot{q}_{j} + \sum_{j=1}^{N_{D}}\sum_{k=1}^{N_{D}} \frac{\partial^2\mathbf{r}}{\partial q_j \partial q_k}\dot{q}_j \dot{q}_k + 2\sum_{j=1}^{N_{D}} \frac{\partial^2\mathbf{r}}{\partial t \partial q_j}\dot{q}_j + \frac{\partial^2\mathbf{r}}{\partial t^2}
|
||||
$$
|
||||
|
||||
**步骤 3: 组合并识别各项**
|
||||
|
||||
现在,我们将步骤 2 中得到的 $\ddot{\mathbf{r}}$ 代入步骤 1 的简化结果中:
|
||||
$$
|
||||
\int_{\mathcal{V}} \rho \left( \sum_{j} \frac{\partial\mathbf{r}^{T}}{\partial q_{j}}\ddot{q}_{j} + \sum_{j,k} \frac{\partial^2\mathbf{r}^{T}}{\partial q_j \partial q_k}\dot{q}_j \dot{q}_k + 2\sum_{j} \frac{\partial^2\mathbf{r}^{T}}{\partial t \partial q_j}\dot{q}_j + \frac{\partial^2\mathbf{r}^{T}}{\partial t^2} \right) \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V}
|
||||
$$
|
||||
将积分分配到每一项,并与方程 (1.7) 的各项进行比对:
|
||||
|
||||
1. **惯性项 (Inertia Term):**
|
||||
$$
|
||||
\sum_{j=1}^{N_D} \left( \int_{\mathcal{V}} \rho \frac{\partial\mathbf{r}^{T}}{\partial q_{j}} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V} \right) \ddot{q}_j \implies m_{ij} = \int_{\mathcal{V}} \rho \frac{\partial\mathbf{r}^{T}}{\partial q_{j}} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V}
|
||||
$$
|
||||
这正是广义质量矩阵 $m_{ij}$ 的定义。
|
||||
|
||||
2. **科里奥利/离心项 (Coriolis/Centrifugal Term):**
|
||||
$$
|
||||
\sum_{j=1}^{N_D}\sum_{k=1}^{N_D} \left( \int_{\mathcal{V}} \rho \frac{\partial^2\mathbf{r}^{T}}{\partial q_j \partial q_k} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V} \right) \dot{q}_j \dot{q}_k \implies h_{ijk} = \int_{\mathcal{V}} \rho \frac{\partial^2\mathbf{r}^{T}}{\partial q_j \partial q_k} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V}
|
||||
$$
|
||||
这定义了与速度二次方相关的系数 $h_{ijk}$。
|
||||
|
||||
3. **陀螺/速度相关项 (Gyroscopic Term):**
|
||||
$$
|
||||
\sum_{j=1}^{N_D} \left( 2 \int_{\mathcal{V}} \rho \frac{\partial^2\mathbf{r}^{T}}{\partial t \partial q_j} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V} \right) \dot{q}_j \implies g_{ij} = 2 \int_{\mathcal{V}} \rho \frac{\partial^2\mathbf{r}^{T}}{\partial t \partial q_j} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V}
|
||||
$$
|
||||
这定义了与速度一次方相关的系数 $g_{ij}$,通常由坐标系的旋转或移动引起。
|
||||
|
||||
4. **时变坐标系引起的力项 (Force Term from Time-Varying Coordinates):**
|
||||
$$
|
||||
\int_{\mathcal{V}} \rho \frac{\partial^2\mathbf{r}^{T}}{\partial t^2} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V} \implies F_{c,i} = \int_{\mathcal{V}} \rho \frac{\partial^2\mathbf{r}^{T}}{\partial t^2} \frac{\partial \mathbf{r}}{\partial q_i} \;d\mathcal{V}
|
||||
$$
|
||||
这项代表了由于坐标系自身的加速度而产生的惯性力。
|
||||
|
||||
**结论**
|
||||
|
||||
将以上所有项代回拉格朗日方程,我们得到:
|
||||
$$
|
||||
\underbrace{\sum_{j=1}^{N_{D}}m_{i j}\ddot{q}_{j} + \sum_{j=1}^{N_{D}}\sum_{k=1}^{N_{D}}h_{i j k}\dot{q}_{j}\dot{q}_{k} + \sum_{j=1}^{N_{D}}g_{i j}\dot{q}_{j} + F_{c,i}}_{\text{from } \frac{d}{dt}(\frac{\partial T}{\partial \dot{q}_i}) - \frac{\partial T}{\partial q_i}} + \frac{\partial V}{\partial q_{i}} + \frac{\partial D}{\partial\dot{q}_{i}} = Q_{i}
|
||||
$$
|
||||
重新排列各项顺序,就得到了与方程 (1.7) 完全一致的形式:
|
||||
$$
|
||||
\sum_{j=1}^{N_{D}}m_{i j}\ddot{q}_{j}+\sum_{j=1}^{N_{D}}g_{i j}\dot{q}_{j}+F_{c,i}+\sum_{j=1}^{N_{D}}\sum_{k=1}^{N_{D}}h_{i j k}\dot{q}_{j}\dot{q}_{k}+\frac{\partial V}{\partial q_{i}}+\frac{\partial D}{\partial\dot{q}_{i}}=Q_{i}
|
||||
$$
|
||||
推导完成。
|
||||
[Timestamp: 2025/07/29 10:10:53]
|
@ -77,7 +77,7 @@ This chapter contains the derivations of the nonlinear equations of motion based
|
||||
The Lagrangian of a structure ${{L}}=T-V$ is given by its total kinetic energy $T$ and the total potential energy $V$ of the conservative forces acting on the structure, e.g. gravity and elastic forces. Using Lagrange’s equations, the nonlinear equations of motion can be derived as
|
||||
结构的拉格朗日量 ${{L}}=T-V$ 由其总动能 $T$ 和作用在结构上的保守力(例如重力和弹力)的总势能 $V$ 给出。利用拉格朗日方程,可以推导出非线性运动方程,如下所示:
|
||||
$$
|
||||
{\frac{d}{d t}}\left({\frac{\partial L}{\partial{\dot{q}}_{i}}}\right)-{\frac{\partial L}{\partial q_{i}}}+{\frac{\partial D}{\partial{\dot{q}}_{i}}}=Q_{i}\;\;{\mathsf{f o r}}\;\;i=1,\ldots,N_{D}
|
||||
{\frac{d}{d t}}\left({\frac{\partial L}{\partial{\dot{q}}_{i}}}\right)-{\frac{\partial L}{\partial q_{i}}}+{\frac{\partial D}{\partial{\dot{q}}_{i}}}=Q_{i}\;\;{\mathsf{f o r}}\;\;i=1,\ldots,N_{D} \tag{1.1}
|
||||
$$
|
||||
|
||||
where $D$ is the Rayleigh dissipation function used to model the internal energy dissipation, and $Q_{i}$ is the generalized force for the generalized coordinate $q_{i}$ due to nonconservative forces handled in the next sections.
|
||||
@ -87,13 +87,13 @@ The Lagrangian is a function of the displacements, velocities, and time
|
||||
|
||||
拉格朗日量是位移、速度和时间的函数。
|
||||
$$
|
||||
L=T\left(t,\mathbf{q},{\dot{\mathbf{q}}}\right)-V\left(t,\mathbf{q}\right)
|
||||
L=T\left(t,\mathbf{q},{\dot{\mathbf{q}}}\right)-V\left(t,\mathbf{q}\right)\tag{1.2}
|
||||
$$
|
||||
|
||||
where the potential energy of the conservative forces are independent of velocities. Using (1.2) and the chain rule, the first term of (1.1) can be expanded as
|
||||
其中保守力的势能与速度无关。利用(1.2)和链式法则,(1.1)的第一项可以展开为
|
||||
$$
|
||||
\sum_{j=1}^{N_{D}}\frac{\partial^{2}T}{\partial{\dot{q}}_{i}\partial{\dot{q}}_{j}}{\ddot{q}}_{j}+\sum_{j=1}^{N_{D}}\frac{\partial^{2}T}{\partial{\dot{q}}_{i}\partial q_{j}}{\dot{q}}_{j}+\frac{\partial}{\partial t}\bigg(\frac{\partial T}{\partial{\dot{q}}_{i}}\bigg)-\frac{\partial T}{\partial q_{i}}+\frac{\partial D}{\partial{\dot{q}}_{i}}+\frac{\partial V}{\partial q_{i}}=Q_{i}
|
||||
\sum_{j=1}^{N_{D}}\frac{\partial^{2}T}{\partial{\dot{q}}_{i}\partial{\dot{q}}_{j}}{\ddot{q}}_{j}+\sum_{j=1}^{N_{D}}\frac{\partial^{2}T}{\partial{\dot{q}}_{i}\partial q_{j}}{\dot{q}}_{j}+\frac{\partial}{\partial t}\bigg(\frac{\partial T}{\partial{\dot{q}}_{i}}\bigg)-\frac{\partial T}{\partial q_{i}}+\frac{\partial D}{\partial{\dot{q}}_{i}}+\frac{\partial V}{\partial q_{i}}=Q_{i}\tag{1.3}
|
||||
$$
|
||||
|
||||
for $i=1,2,\dots,N_{D}$ . Here, the first term constitutes the acceleration dependent forces, whereas the other terms are only dependent on the time $t$ and the statevariables, the displacements $\mathbf{q}$ and velocities $\dot{\mathbf{q}}$ . We will now take a closer look at the first four inertia force terms given by the kinetic energy.
|
||||
@ -103,29 +103,29 @@ The total kinetic energy is the integral of the kinetic energy of each particle
|
||||
|
||||
总动能是结构在整个体积 $\mathcal{V}$ 上每个粒子的动能积分:
|
||||
$$
|
||||
T=\int_{\mathcal{V}}\frac{1}{2}\;\rho\;\dot{\mathbf{r}}^{T}\dot{\mathbf{r}}\;d\mathcal{V}
|
||||
T=\int_{\mathcal{V}}\frac{1}{2}\;\rho\;\dot{\mathbf{r}}^{T}\dot{\mathbf{r}}\;d\mathcal{V}\tag{1.4}
|
||||
$$
|
||||
|
||||
where $()^{T}$ denotes to the transpose of a matrix or a vector (single columned matrix), and r˙ is the velocity vector of the particle given as the time derivative of its position vector $\boldsymbol{\mathsf{r}}=\boldsymbol{\mathsf{r}}(t,\mathbf{q})$ that may be explicit time dependent e.g. for substructures that are rotating with a prescribed average speed. The velocity vector can be expanded to
|
||||
其中 $()^{T}$ 表示矩阵或向量(单列矩阵)的转置,$\dot{\mathbf{r}}$ 是粒子的速度向量,表示为其位置向量 $\boldsymbol{\mathsf{r}}=\boldsymbol{\mathsf{r}}(t,\mathbf{q})$ 的时间导数,该位置向量可能显式地依赖于时间,例如对于以给定平均速度旋转的子结构。速度向量可以展开为
|
||||
$$
|
||||
\dot{\pmb{r}}=\frac{d\pmb{r}}{d t}=\sum_{j=1}^{N_{D}}\frac{\partial\pmb{r}}{\partial q_{j}}\dot{q}_{j}+\frac{\partial\pmb{r}}{\partial t}
|
||||
\dot{\pmb{r}}=\frac{d\pmb{r}}{d t}=\sum_{j=1}^{N_{D}}\frac{\partial\pmb{r}}{\partial q_{j}}\dot{q}_{j}+\frac{\partial\pmb{r}}{\partial t}\tag{1.5}
|
||||
$$
|
||||
|
||||
from which these properties of the position and velocity vectors can be shown
|
||||
从中可以证明位置和速度向量的这些特性
|
||||
$$
|
||||
{\frac{\partial{\dot{\mathbf{r}}}}{\partial{\dot{q}}_{i}}}={\frac{\partial\mathbf{r}}{\partial q_{i}}}\quad{\mathsf{a n d}}\quad{\frac{\partial^{2}{\dot{\mathbf{r}}}}{\partial{\dot{q}}_{i}\partial q_{j}}}={\frac{\partial\mathbf{r}}{\partial q_{i}\partial q_{j}}}={\frac{\partial^{2}{\dot{\mathbf{r}}}}{\partial q_{i}\partial{\dot{q}}_{j}}}
|
||||
{\frac{\partial{\dot{\mathbf{r}}}}{\partial{\dot{q}}_{i}}}={\frac{\partial\mathbf{r}}{\partial q_{i}}}\quad{\mathsf{a n d}}\quad{\frac{\partial^{2}{\dot{\mathbf{r}}}}{\partial{\dot{q}}_{i}\partial q_{j}}}={\frac{\partial\mathbf{r}}{\partial q_{i}\partial q_{j}}}={\frac{\partial^{2}{\dot{\mathbf{r}}}}{\partial q_{i}\partial{\dot{q}}_{j}}}\tag{1.6}
|
||||
$$
|
||||
|
||||
Substituting (1.4) into (1.3) and using the properties of (1.5) and (1.6), the nonlinear equations of motion can be written as
|
||||
|
||||
将 (1.4) 代入 (1.3) 并利用 (1.5) 和 (1.6) 的性质,非线性运动方程可以写为
|
||||
$$
|
||||
\sum_{j=1}^{N_{D}}m_{i j}\ddot{q}_{j}+\sum_{j=1}^{N_{D}}g_{i j}\dot{q}_{j}+F_{c,i}+\sum_{j=1}^{N_{D}}\sum_{k=1}^{N_{D}}h_{i j k}\dot{q}_{j}\dot{q}_{k}+\frac{\partial V}{\partial q_{i}}+\frac{\partial D}{\partial\dot{q}_{i}}=Q_{i}
|
||||
\sum_{j=1}^{N_{D}}m_{i j}\ddot{q}_{j}+\sum_{j=1}^{N_{D}}g_{i j}\dot{q}_{j}+F_{c,i}+\sum_{j=1}^{N_{D}}\sum_{k=1}^{N_{D}}h_{i j k}\dot{q}_{j}\dot{q}_{k}+\frac{\partial V}{\partial q_{i}}+\frac{\partial D}{\partial\dot{q}_{i}}=Q_{i}\tag{1.7}
|
||||
$$
|
||||
|
||||
where the summation coefficients and the acceleration force $F_{c,i}$ can be derived solely from the partial time and displacement derivatives of the position vector as
|
||||
|
||||
其中,求和系数和加速度力 $F_{c,i}$ 仅可从位置向量对时间分量和位移分量的偏导数中导出
|
||||
$$
|
||||
\begin{array}{l}{\displaystyle m_{i j}=\int_{\mathcal{V}}\rho\left(\frac{\partial\mathbf{r}^{T}}{\partial q_{i}}\frac{\partial\mathbf{r}}{\partial q_{j}}\right)d\boldsymbol{\nu}}\\ {\displaystyle g_{i j}=\int_{\mathcal{V}}2\rho\left(\frac{\partial\mathbf{r}^{T}}{\partial q_{i}}\frac{\partial^{2}\mathbf{r}}{\partial t\partial q_{j}}\right)d\boldsymbol{\nu}}\\ {\displaystyle h_{i j k}=\int_{\mathcal{V}}\rho\left(\frac{\partial\mathbf{r}^{T}}{\partial q_{i}}\frac{\partial^{2}\mathbf{r}}{\partial q_{j}\partial q_{k}}\right)d\boldsymbol{\nu}}\\ {\displaystyle F_{c,i}=\int_{\mathcal{V}}\rho\left(\frac{\partial\mathbf{r}^{T}}{\partial q_{i}}\frac{\partial^{2}\mathbf{r}}{\partial t^{2}}\right)d\boldsymbol{\nu}}\end{array}
|
||||
$$
|
||||
|
16
多体+耦合求解器/SD ED AD 流程及数据交互/流程.md
Normal file
16
多体+耦合求解器/SD ED AD 流程及数据交互/流程.md
Normal file
@ -0,0 +1,16 @@
|
||||
|
||||
|
||||
fast_advance_states()
|
||||
- ed_updatestates
|
||||
- SolveOption2a_Inp2BD
|
||||
- ed_calc_output 更新数据
|
||||
|
||||
- BD updatestates
|
||||
- SolveOption2b_Inp2IfW Ifw根据ED结果更新
|
||||
|
||||
- ifw updatestates
|
||||
- SolveOption2c_Inp2AD_SrvD
|
||||
- ifw calcoutput
|
||||
- AD_InputSolve_IfW
|
||||
- SrvD_InputSolve
|
||||
|
File diff suppressed because it is too large
Load Diff
Loading…
x
Reference in New Issue
Block a user