Time-dependent mechanical behavior of sweet sorghum stems

Area of Science:

• Agricultural Engineering
• Biomechanical Engineering
• Plant Science

Background:

• Grasses are globally significant crops but prone to lodging (structural failure) due to wind, impacting yield.
• The biomechanical mechanisms underlying grass stem failure are not well understood, hindering efforts to improve crop stability.
• Systematic studies on the biomechanical behavior of grass stems are lacking.

Purpose of the Study:

• To investigate the biomechanical properties of sweet sorghum (Sorghum bicolor (L.) Moench) stems.
• To focus on the time-dependent mechanical behavior of sorghum stems under stress.
• To provide insights into the factors contributing to stem lodging in grasses.

Main Methods:

• Conducted uniaxial compression tests on pith and stem specimens of the Della sorghum cultivar.
• Applied ramp and creep loading conditions to assess stress-strain behavior.
• Analyzed the time-dependent and nonlinear mechanical responses of the plant tissues.

Main Results:

• Sorghum stem and pith specimens exhibited significantly nonlinear and time-dependent stress-strain behavior.
• The observed behavior suggests contributions from poroelasticity (water migration) and viscoelasticity (macromolecular rearrangement).
• Sorghum stems do not behave as simple reversible elastic materials.

Conclusions:

• Understanding the time-dependent biomechanical properties of sorghum stems is essential for predicting lodging.
• These properties influence the mechanical stability of the stem under field conditions, such as wind loading.
• Further research into these time-dependent characteristics is crucial for developing lodging-resistant grass crops.