Comparison table of maximum failure stresses and failure strains.

Comparison table of maximum failure stresses and failure strains.</p

Grey scale values versus relative light intensity curve.

Grey scale values versus relative light intensity curve.</p

Cylindrical object placed perpendicular to the ground.

Cylindrical object placed perpendicular to the ground.</p

Microscopic changes in the interior of solid propellants under uniaxial tension.

Microscopic changes in the interior of solid propellants under uniaxial tension.</p

Vertical cylindrical measurement results.

(a) Point cloud of measurement results. (b) Cylindrical radius fitting diagram.</p

Relative light intensity distribution of the actual image before and after denoising.

Relative light intensity distribution of the actual image before and after denoising.</p

Sub-pixel coordinates and their final light intensity gradient finding range.

Sub-pixel coordinates and their final light intensity gradient finding range.</p

S1 File -

As the level of engineering technology increases, the mechanical problems posed in the area of mechanics become complex and diverse. The traditional measurement methods and content of past measurements no longer meet the needs, so more advanced experimental methods are needed to accurately measure the three-dimensional shape of objects and their deformations. Nitrate ester plasticized polyether (NEPE) propellants, are the highest energy solid propellant that have been applied in public reports in the world. Due to the material properties of the material itself, its mechanical properties cannot be accurately measured by conventional methods. This paper proposes a simple and highly accurate optical measurement method to study the volume change rate, Poisson’s ratio and true stress-strain curves of NEPE at different displacement loading rates of NEPE. In this paper, the strain of solid propellant NEPE in three directions during unidirectional stretching was measured by defocusing method and digital image correlation(DIC) method and the volume change rate, Poisson’s ratio and true stress-strain curves of NEPE under different stretching rates were obtained. The measured damage initiation engineering strain of NEPE at different tensile strain rates is 0.4687.</div

Experimental instruments and measurement system.

(a) The deformation (in plain) measurement system. (b) The deformation (out of plain) measurement system.</p

Measurement results of a column placed at an angle.

Measurement results of a column placed at an angle.</p