mujoco

<mujoco>
  <option>
    <flag sleep="enable" constraint="disable" contact="disable" gravity="disable"/>
  </option>

  <worldbody>
    <body name="flex_body">
      <freejoint/>
      <inertial pos="0 0 0" mass="1" diaginertia="0.01 0.01 0.01"/>
      <flexcomp name="f1" type="grid" dim="1" count="3 1 1"
                spacing=".05 .05 .05" radius=".01" mass="1">
        <edge equality="true" solref="0.15 0.2"/>
      </flexcomp>
    </body>
  </worldbody>
</mujoco>