Center for Composite Materials - University of Delaware

Research Summary

Energy and Bond Strength Development during Ultrasonic Consolidation

Authors: Greg Kelly, Suresh Advani and John W. Gillespie, Jr

Ultrasonic Condoslidation

• Ultrasonic Consolidation (UC) is a solid-state bonding process in which thin foils or metal-matrix composite (MMC) tapes can be built-up layer by layer
• Process Components:
-Sonotrode
-Foils / Tapes
-Substrate / Anvil
• Variable Process Parameters
-Sonotrode Oscillation Amplitude (λ) and Frequency (f)
-Clamping Force (Fc)
-Sonotrode Speed (S)

OBJECTIVE AND MOTIVATION

• The objective of this work was to develop a method to predict UC bond strength by establishing a relationship between UC process parameters, weld energy and bond strength
• Previously, trial and error was necessary in order to identify a window of process parameters that create high quality UC bonds. The window of optimum process parameters varies with material type, material geometry and surface roughness
• High quality UC bonds are defined by a bond strength approaching that of the base material while all components remain aligned during processing
• Poor bond quality can arise due to the following:
-If low λ, low Fc, and high S are used during UC: bonds are weak or nonexistent
-If high λ, high Fc, and low S are used during UC: excessive deformation may occur in the foil leading to damage & misalignment

WELD ENERGY

THERMAL ANALYSIS

• A 2D thermal finite element mode in Abaqus 6.11-1 is used to establish a relationship between E, tw and the temperature increase during UC (ΔT)
• An infrared (IR) camera is used to measure the temperature field and the steady-state temperature increase (ΔTss) is identified

RESULTS

CONCLUSIONS

• Weld energy was calculated based on temperature and weld time.
• A linear trend was identified between the weld energy and the peel strength of UC bonds.
• Relatively low processing temperatures were measured confirming that solid-state bonding occurs
• Future Work:
-Utilize IR camera and feedback control to monitor and adjust UC process parameters in real-time to achieve desired bond properties

ACKNOWLEDGEMENTS

• Jennifer Sietins
• Scott Just
• This work is supported by the Army Research Laboratory through the Composite Materials Research program.

REFERENCES

Kelly, G.S., Just, M.S., Advani, S.G., Gillespie, J.W., 2014. Energy and bond strength development during ultrasonic consolidation. Journal of Materials Processing Technology 214, 1665 – 1672.

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