Formability Assessment of C1100 Pure-Copper Tube Considering an Enhanced Modified Maximum Force Criterion.

Area of Science:

• Materials Science
• Mechanical Engineering
• Manufacturing Processes

Background:

• Strain localization models like Modified Maximum Force Criterion (MMFC) and Marciniak-Kuczynski (MK) are crucial for predicting material failure in metal forming.
• These models were originally developed for sheet metals and their applicability to tubular materials requires investigation.

Purpose of the Study:

• To evaluate the predictive capabilities of the MMFC and MK models for the forming limit diagram (FLD) of C1100 pure-copper tubes.
• To develop and validate an enhanced MMFC model (MMFC2) for tubular materials.
• To assess the integration of theoretical FLDs into finite element analysis (FEA) for predicting tube bursting.

Main Methods:

• Uniaxial tensile tests were conducted to characterize the hardening behavior of C1100 pure-copper tubes using a Swift-Voce hardening law.
• A MATLAB code was developed to theoretically predict the FLD using the enhanced MMFC2 and the standard MK models.
• Experimental validation was performed using tube expansion tests.
• Finite element simulations incorporated the predicted FLDs to forecast tube bursting behavior.

Main Results:

• The constitutive model accurately captured the hardening behavior of the copper tubes.
• Theoretical FLDs were generated using both the MMFC2 and MK models.
• Experimental results from tube expansion tests validated the theoretical FLD predictions.
• The MMFC2 model showed closer agreement with experimental FLD data than the MK model.
• FEA simulations utilizing the MMFC2-predicted FLD effectively forecasted tube bursting.

Conclusions:

• The enhanced Modified Maximum Force Criterion (MMFC2) model offers improved accuracy for predicting forming limit diagrams (FLDs) in tubular materials compared to the traditional Marciniak-Kuczynski (MK) model.
• The MMFC2 model holds significant potential for enhancing the simulation accuracy of forming processes and failure prediction in tube manufacturing.
• Integrating theoretically derived FLDs into FEA provides a valuable tool for predicting the bursting behavior of tubes.