New Edge Crush Test Configuration Enhanced with Full-Field Strain Measurements

Area of Science:

• Materials Science
• Mechanical Engineering
• Structural Analysis

Background:

• The standard edge crush test (ECT) measures corrugated cardboard strength but fails to determine compressive stiffness.
• Accurate measurement of displacements and strains is a significant challenge for existing lab equipment.
• Compressive stiffness is a critical parameter for structural applications of corrugated board.

Purpose of the Study:

• To develop a reliable method for determining the compressive stiffness and orthotropic material stiffness matrix of corrugated cardboard.
• To address the limitations of current testing methodologies in measuring stiffness accurately.
• To propose a new experimental setup and algorithm for comprehensive stiffness characterization.

Main Methods:

• Utilized two corrugated cardboard samples: one cut crosswise to the wave direction and another at a 45° angle.
• Employed an optical system with digital image correlation (DIC) for non-contact measurement of surface displacements and strains.
• Developed a simple algorithm to calculate all stiffness parameters from the DIC measurements.

Main Results:

• Successfully determined the stiffness in the loaded direction of orthotropy and the full orthotropic material stiffness matrix.
• The non-contact DIC system provided reliable strain and displacement data, avoiding errors associated with crosshead measurements.
• The proposed method and algorithm efficiently characterized the sought stiffness parameters.

Conclusions:

• The developed method accurately measures the compressive stiffness and full orthotropic material stiffness matrix of corrugated cardboard.
• This approach overcomes the limitations of traditional methods, offering a more reliable assessment of material properties.
• The results align with those obtained through homogenization procedures, validating the proposed technique.