有人知道如何在乳胶中表示刚体的平衡吗？

Question

该符号用于指示外部、内部和反应力轴的正方向。

用于《静力学：Hibbler 工程力学》一书中

Answer 1

欢迎来到 TeX.SE！！！

Ti 的初步应用钾Z.如果您不需要缩放符号，这可能会有所帮助：

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}

\NewDocumentCommand{\auxm}{m}
{% 
  \begin{tikzpicture}[baseline=(a.south),line width=0.4pt,xscale=#1]
    \node[inner sep=0,outer sep=0] (a) at (0,0) {\vphantom{a}};
    \node at (0,0) {$+$};
    \draw[->] (-150:1.25ex) arc (-150:150:1.25ex);
  \end{tikzpicture}%
}%
\NewDocumentCommand{\auxx}{m}
{% 
  \begin{tikzpicture}[baseline=(a.south),line width=0.4pt,xscale=#1]
    \node[inner sep=0,outer sep=0] (a) at (0,0) {\vphantom{a}};
    \node at (0,1ex) {$+$};
    \draw[->] (-1.25ex,0) -- (1.25ex,0);
  \end{tikzpicture}%
}%
\NewDocumentCommand{\auxy}{m}
{% 
  \begin{tikzpicture}[baseline=(a.south),line width=0.4pt,yscale=#1]
    \node[inner sep=0,outer sep=0] (a) at (0,0) {\vphantom{a}};
    \node at (-1.25ex,0) {$+$};
    \draw[->] (0,-1.25ex) -- (0,1.25ex);
  \end{tikzpicture}%
}%
\NewDocumentCommand{\summ}{O{1}}{\mathop{\auxm{#1}\kern-0.4em\sum}}
\NewDocumentCommand{\sumx}{O{1}}{\mathop{\auxx{#1}\kern-0.4em\sum}}
\NewDocumentCommand{\sumy}{O{1}}{\mathop{\auxy{#1}\kern-0.1em\sum}}

\begin{document}
In a line $\summ M_O=0$, $\sumx[-1] F_x=0$, $\sumy F_y=0$ or outside:
\begin{gather*}
\summ M_O=0, \quad \sumx F_x=0,\quad \sumy F_y=0,\\
\summ[-1] M_O=0, \quad \sumx[-1] F_x=0,\quad \sumy[-1] F_y=0,
\end{gather*}
\end{document}

Answer 2

如果您同意使用 TikZ 来生成箭头，那么这就是我的做法。

\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{tikz}

% Equilibrium symbols
\newcommand\curvedarrow{%
    \mathop{\tikz[scale=0.24]{\draw[thick,-stealth]
        (1,0.75) to [out=225,in=135] (1,-0.75);}}%
}
\newcommand\plusrightarrow{%
    \mathop{\tikz[scale=0.24]{\draw[thick,-stealth]
        (-0.75,0) -- (0.75,0) node [midway,above] {+};}}%
}
\newcommand\plusleftarrow{%
    \mathop{\tikz[scale=0.24]{\draw[thick,-stealth]
        (0.75,0) -- (-0.75,0) node [midway,above] {+};}}%
}
\newcommand\plusuparrow{%
    \mathop{\tikz[scale=0.24]{\draw[thick,-stealth]
        (0,-0.75) -- (0,0.75) node [midway,left] {+};}}%
}
\newcommand\plusdownarrow{%
    \mathop{\tikz[scale=0.24]{\draw[thick,-stealth]
        (0,0.75) -- (0,-0.75) node [midway,left] {+};}}%
}

\newcommand{\rforce}[1]{\mathbin{\plusrightarrow\Sigma F_{#1}}}
\newcommand{\lforce}[1]{\mathbin{\plusleftarrow\Sigma F_{#1}}}
\newcommand{\uforce}[1]{\mathbin{\plusuparrow\Sigma F_{#1}}}
\newcommand{\dforce}[1]{\mathbin{\plusdownarrow\Sigma F_{#1}}}
\newcommand{\moment}[1]{\mathbin{+\curvedarrow\Sigma M_{#1}}}

\begin{document}
\begin{gather*}
    \moment{O} = 0 \qquad \rforce{x} = 0 \qquad \uforce{y} = 0
\end{gather*}

\end{document}

希望有所帮助。