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Abstract Single point incremental forming (SPIF) is a flexible manufacturing process that has applications in industries ranging from biomedical to automotive. In addition to rapid prototyping, which requires easy adaptations in geometry or material for design changes, control of the final part properties is desired. One strategy that can be implemented is stress superposition, which is the application of additional stresses during an existing manufacturing process. Tensile and compressive stresses applied during SPIF showed significant effects on the resulting microstructure in stainless steel 304 truncated square pyramids. Specifically, the amount of martensitic transformation was increased through stress superposed incremental forming. Finite element analyses with advanced material modeling supported that the stress triaxiality had a larger effect than the Lode angle parameter on the phase transformation that occurred during deformation. By controlling the amount of tensile and compressive stresses superposed during incremental forming, the microstructure of the final component can be manipulated based on the intended application and desired final part properties.
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Giant reversible elongation upon cooling and contraction upon heating for a crosslinked cis poly(1,4-butadiene) system at temperatures below zero Celsius
Abstract Polymers with reversible elongation upon cooling (EUC) and contraction upon heating (CUH) enabled applications in actuators, fasteners, dampers, grippers, swimmers, sealants, etc. With the current working temperature being limited to mainly above zero Celsius, applications for subzero Celsius environments are obstructed. In addition, current reversible actuation needs a constant tensile load, or for the best case, under zero tensile load. Reversible EUC and CUH under compressive load is almost impossible and has not been explored. In this work, acispoly(1,4-butadiene) based system has been developed. Actuated below zero Celsius, 69% EUC occurred under a tensile load; and 6.2% EUC and 17.9% CUH occurred under 0.05 MPa compressive load. The reversible actuation was driven by both entropy and enthalpy, which was validated by a series of characterization tools.
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- Award ID(s):
- 1647650
- PAR ID:
- 10153712
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 8
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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