\documentclass{article}
\usepackage{breqn}
\usepackage[fleqn]{amsmath}
\usepackage{amsthm}
\usepackage{amssymb}
\usepackage{xepersian}
\settextfont{XB Zar}
\setlatintextfont{Linux Libertine}% از نسخه ۱.۰.۴ زی‌پرشین این دستور الزامی نیست و قلم  پیش‌فرض تک مورد استفاده قرار می‌گیرد.
\setdigitfont{XB Zar}
\title{شکستن فرمول‌های خیلی طولانی}
\author{}
\begin{document}
\maketitle
با استفاده از بستهٔ \lr{breqn} می‌توانید فرمول را بصورت خودکار بشکنید و نیازی به محیط \lr{align} ندارید. \lr{breqn} جزو بسته \lr{mh} می‌باشد.

\begin{equation}
\begin{split}
&\left( \hat{E}h+2{{E}^{s}} \right)\,\left[ \sum\limits_{m=1}^{{{N}_{x}}}{B_{im}^{x}}{{u}_{mj}}+\left( \sum\limits_{m=1}^{{{N}_{x}}}{A_{im}^{x}}{{w}_{mj}} \right)\left( \sum\limits_{m=1}^{{{N}_{x}}}{B_{im}^{x}}{{w}_{mj}} \right) \right]+\\
&\left[ \nu \hat{E}h+Gh+2{{E}^{s}} \right]\,\left[ \sum\limits_{m=1}^{{{N}_{x}}}{\sum\limits_{n=1}^{{{N}_{y}}}{A_{im}^{x}A_{jn}^{y}{{v}_{mn}}}} \right.+\left( \sum\limits_{n=1}^{{{N}_{y}}}{A_{jn}^{y}}{{w}_{in}} \right).\\
&\left. \left( \sum\limits_{m=1}^{{{N}_{x}}}{\sum\limits_{n=1}^{{{N}_{y}}}{A_{im}^{x}A_{jn}^{y}{{w}_{mn}}}} \right) \right]\left[ Gh+2\left( \left. 2{{\mu }^{s}}-{{\tau }^{s}} \right) \right. \right]\left[ \sum\limits_{n=1}^{{{N}_{y}}}{B_{jn}^{y}{{u}_{in}}} \right.+\\
&\left. \left( \sum\limits_{m=1}^{{{N}_{x}}}{A_{im}^{x}}{{w}_{mj}} \right)\left( \sum\limits_{n=1}^{{{N}_{y}}}{B_{jn}^{y}{{w}_{in}}} \right) \right]=\rho h{{\ddot{u}}_{ij}}-\mu \rho h\left( \sum\limits_{m=1}^{{{N}_{x}}}{B_{im}^{x}}{{{\ddot{u}}}_{mj}} \right.+\\
&\left. \sum\limits_{n=1}^{{{N}_{y}}}{B_{jn}^{y}}{{{\ddot{u}}}_{in}} \right)\\     
\end{split}
\end{equation}
            
\begin{dmath}
\left( \hat{E}h+2{{E}^{s}} \right)\left[ \sum\limits_{n=1}^{{{N}_{y}}}{B_{jn}^{y}{{v}_{in}}}+\left( \sum\limits_{n=1}^{{{N}_{y}}}{A_{jn}^{y}{{w}_{in}}} \right)\left( \sum\limits_{n=1}^{{{N}_{y}}}{B_{jn}^{y}{{w}_{in}}} \right) \right]+\left( \nu \hat{E}h+Gh+2{{E}^{s}} \right)\left[ \sum\limits_{m=1}^{{{N}_{x}}}{\sum\limits_{n=1}^{{{N}_{y}}}{A_{im}^{x}A_{jn}^{y}{{u}_{mn}}}} \right.+\left( \sum\limits_{m=1}^{{{N}_{x}}}{A_{im}^{x}}{{w}_{mj}} \right)\left( \sum\limits_{m=1}^{{{N}_{x}}}{\sum\limits_{n=1}^{{{N}_{y}}}{A_{im}^{x}A_{jn}^{y}{{w}_{mn}}}} \right)+\left[ Gh \right.+\left. 2\left( 2{{\mu }^{s}}-{{\tau }^{s}} \right) \right]\left[ \sum\limits_{m=1}^{{{N}_{x}}}{B_{im}^{x}}{{v}_{mj}}+ \right. \left. \left( \sum\limits_{n=1}^{{{N}_{y}}}{A_{jn}^{y}}{{w}_{in}} \right)\left( \sum\limits_{m=1}^{{{N}_{x}}}{B_{im}^{x}}{{w}_{mj}} \right) \right]=\rho h{{\ddot{v}}_{ij}}-\mu \rho h\left( \sum\limits_{m=1}^{{{N}_{x}}}{B_{im}^{x}}{{{\ddot{v}}}_{mj}} \right.+ \left. +\sum\limits_{n=1}^{{{N}_{y}}}{B_{jn}^{y}}{{{\ddot{v}}}_{in}} \right)
\end{dmath}


\begin{equation}
\begin{split}
&\left\{ \left[ {{T}_{44}}\left( 1,1 \right)+2{{T}_{44}}\left( 5,1 \right)+{{T}_{44}}\left( 2,1 \right) \right]\left( \sum\limits_{m=1}^{{{N}_{\xi }}}{\bar{D}_{im}^{\xi }}w_{mj}^{b}+B_{i1}^{\xi }\kappa _{1j}^{bx}+B_{i1}^{\xi }\kappa _{{{N}_{\xi }}j}^{b\xi } \right)+ \right.\\ 
&\left[ {{T}_{44}}\left( 1,2 \right) \right.+2{{T}_{44}}\left( 5,2 \right)+\left. {{T}_{44}}\left( 2,2 \right) \right]\left( \sum\limits_{n=1}^{{{N}_{\eta }}}{\bar{D}_{jn}^{\eta }w_{in}^{b}}+B_{j1}^{\eta }\kappa _{i1}^{b\eta }+B_{j1}^{\eta }\kappa _{i{{N}_{\eta }}}^{b\eta } \right)+\\
&\left[ {{T}_{44}}\left( 1,3 \right) \right.+2{{T}_{44}}\left( 5,3 \right)+\left. {{T}_{44}}\left( 2,3 \right) \right]\sum\limits_{n=1}^{{{N}_{\eta }}}{A_{jn}^{\eta }}\left( \sum\limits_{m=1}^{{{N}_{\xi }}}{\bar{C}_{im}^{\xi }}w_{mn}^{b}+A_{i1}^{\xi }\kappa _{1n}^{b\xi } \right.+A_{i{{N}_{\xi }}}^{\xi }.\\ 
&\left. \kappa _{{{N}_{\xi }}n}^{b\xi } \right)+\left[ {{T}_{44}}\left( 1,4 \right)+2{{T}_{44}}\left( 5,4 \right)+{{T}_{44}}\left( 2,4 \right) \right]\sum\limits_{m=1}^{{{N}_{\xi }}}{A_{im}^{\xi }}\left( \sum\limits_{n=1}^{{{N}_{\eta }}}{\bar{C}_{jn}^{\eta }}w_{mn}^{b} \right.+A_{j1}^{\eta }\kappa _{1n}^{b\eta }\\
&\left. +A_{j{{N}_{\eta }}}^{\eta }\kappa _{{{N}_{\eta }}n}^{b\eta } \right)+\left. \left[ {{T}_{44}}\left( 1,5 \right)+2{{T}_{44}}\left( 5,5 \right)+{{T}_{44}}\left( 2,5 \right) \right]\sum\limits_{m=1}^{{{N}_{\xi }}}{\sum\limits_{n=1}^{{{N}_{\eta }}}{B_{im}^{\xi }B_{jn}^{\eta }}w_{mn}^{b}} \right\}2\mu {{\tau }^{s}}\\
&-2\mu {{\tau }^{s}}\left\{ \left[ {{T}_{44}}\left( 1,1 \right)\hspace{0.15 cm}+ \right.2{{T}_{44}}\left( 5,1 \right)\hspace{0.15 cm}+\left. {{T}_{44}}\left( 2,1 \right) \right]\sum\limits_{m=1}^{{{N}_{\xi }}}{D_{im}^{\xi }}w_{mj}^{s}\hspace{0.15 cm}+ \right.\left[ {{T}_{44}}\left( 1,2 \right) \right.+\\
&2{{T}_{44}}\left( 5,2 \right)+\left. {{T}_{44}}\left( 2,2 \right) \right]\sum\limits_{n=1}^{{{N}_{\eta }}}{D_{jn}^{\eta }w_{in}^{s}}+\left[ {{T}_{44}}\left( 1,3 \right) \right.+2{{T}_{44}}\left( 5,3 \right)+\left. {{T}_{44}}\left( 2,3 \right) \right].\\ 
&\sum\limits_{m=1}^{{{N}_{\xi }}}{\sum\limits_{n=1}^{{{N}_{\eta }}}{C_{im}^{\xi }A_{jn}^{\eta }}w_{mn}^{s}}+\left[ {{T}_{44}}\left( 1,4 \right)+2{{T}_{44}}\left( 5,4 \right)+{{T}_{44}}\left( 2,4 \right) \right]\sum\limits_{m=1}^{{{N}_{\xi }}}{\sum\limits_{n=1}^{{{N}_{\eta }}}{A_{im}^{\xi }C_{jn}^{\eta }}w_{mn}^{s}}+\\ 
&\left. \left[ {{T}_{44}}\left( 1,5 \right)+2{{T}_{44}}\left( 5,5 \right)+{{T}_{44}}\left( 2,5 \right) \right]\sum\limits_{m=1}^{{{N}_{\xi }}}{\sum\limits_{n=1}^{{{N}_{\eta }}}{B_{im}^{\xi }B_{jn}^{\eta }}w_{mn}^{s}} \right\}+\left( kGh+2{{\tau }^{s}} \right).\\
&\left[ {{T}_{22}}\left( 1,1 \right)\sum\limits_{m=1}^{{{N}_{\xi }}}{B_{im}^{\xi }} \right.w_{mj}^{s}+{{T}_{22}}\left( 1,2 \right)\sum\limits_{n=1}^{{{N}_{\eta }}}{B_{jn}^{\eta }}w_{in}^{s}+{{T}_{22}}\left( 1,3 \right)\left. \sum\limits_{m=1}^{{{N}_{\xi }}}{\sum\limits_{n=1}^{{{N}_{\eta }}}{A_{im}^{\xi }A_{jn}^{\eta }w_{mn}^{s}}} \right]\\ 
&+\left( 2{{\tau }^{s}}+\mu {{m}_{0}}\frac{{{\partial }^{2}}}{\partial {{t}^{2}}} \right)\left[ {{T}_{22}}\left( 1,1 \right)\sum\limits_{m=1}^{{{N}_{\xi }}}{B_{im}^{\xi }} \right.\left( w_{mj}^{b}+w_{mj}^{s} \right)+{{T}_{22}}\left( 1,2 \right)\sum\limits_{n=1}^{{{N}_{\eta }}}{B_{jn}^{\eta }}w_{in}^{b}\\
&\left. +w_{in}^{s} \right)+\left. \sum\limits_{m=1}^{{{N}_{\xi }}}{\sum\limits_{n=1}^{{{N}_{\eta }}}{A_{im}^{\xi }A_{jn}^{\eta }\left( w_{mn}^{b}+w_{mn}^{s} \right)}} \right]={{m}_{0}}\frac{{{\partial }^{2}}\left( w_{ij}^{b}+w_{ij}^{s} \right)}{\partial {{t}^{2}}} 
\end{split}
\end{equation}
\end{document}