Ordered buckling structures in a twisted crimped tube

Area of Science:

• Materials Science
• Mechanical Engineering
• Soft Matter Physics

Background:

• Thin shells and tubes buckle and wrinkle when subjected to sufficient twisting.
• The resulting geometric configurations can range from highly ordered to completely disordered.
• Hybrid boundary conditions, such as one end cylindrical and the other flat, introduce unique buckling behaviors.

Purpose of the Study:

• To investigate the buckling and structural evolution of a tube with hybrid boundary conditions under torsion.
• To explore methods for controlling the formation of ordered structures in twisted tubes.
• To understand the influence of pre-creasing and material thickness on the mechanical response and geometry.

Main Methods:

• Experimental analysis of a tube with one cylindrical and one flat (crimped) end under controlled twisting.
• Introduction of pre-creases along the tube's length before twisting.
• Measurement of torque and observation of structural changes as a function of twist angle and material thickness.

Main Results:

• Pre-creasing the tube before twisting induces an ordered structure of repeating triangular facets with varying orientations.
• This pre-creasing results in a more elastic torque response compared to uncreased tubes.
• Ordered structures are localized to pre-creased segments, and in thicker tubes, ordered structures can form spontaneously without pre-creasing.

Conclusions:

• Pre-creasing is an effective method to control the buckling of twisted tubes, leading to predictable, ordered structures and modified mechanical properties.
• The formation of ordered structures is dependent on parameters like pre-creasing, material thickness, and twist angle.
• This research offers insights into designing ordered structures in soft materials by controlling thin shell buckling.