# How to draw torsion prismatic beams in tikz?

I'm new in Tikz but I want to draw this objects:

Can anyone give some good advice, or help?

• Welcome to TeX.SX. Questions about how to draw specific graphics that just post an image of the desired result are really not reasonable questions to ask on the site. Please post a minimal compilable document showing that you've tried to produce the image and then people will be happy to help you with any specific problems you may have. See minimal working example (MWE) for what needs to go into such a document. – ChrisS Apr 18 '15 at 7:29
• not even sure if this is possible, crossing fingers for z buffer=sort to do the trick – 1010011010 Apr 18 '15 at 8:16

Using the assumption that cross-sections behave as rigid bodies:

\documentclass{article}
\usepackage{pgfplots}

\pgfplotsset{compat=1.12}
\begin{document}
\begin{tikzpicture}[
declare function={squarex(\t) =
(\t < 0.25) ? 1 : (
(\t < 0.5) ? (1 - (\t-0.25) * 8) : (
(\t < 0.75) ? -1 : (-1 + (\t - 0.75) * 8)
)
;},
declare function={squarey(\t) =
(\t < 0.25) ? (-1 + \t*8) : (
(\t < 0.5) ? 1 : (
(\t < 0.75) ? (1 - (\t - 0.5) * 8) : -1
)
;}
]
\begin{axis}[
axis equal image,
z buffer=sort,
hide axis,
domain=0:1, y domain = 0:10, samples y = 25,
ylabel =y, xlabel=x,
clip=false
]

z buffer=none, domain=0:330, samples y=1,
ultra thick, black, -latex] (
-0.5,
{sin(x)*1.5},
{cos(x)*1.5}
);

y,
{squarex(x) * cos(y*9) - squarey(x) * sin(y*9)},
{squarex(x) * sin(y*9) + squarey(x) * cos(y*9)}
);

\addplot3 [z buffer=auto, fill=yellow!50, draw=black] table {
x y z
10 -1 -1
10 1 -1
10 1 1
10 -1 1
10 -1 -1
};


• @Acatka: Replace squarex(x) with cos(x*360) and squarey(x) with sin(x*360). – Jake Apr 18 '15 at 13:02