Download Large deformation, instabilities, damage and activity in soft materials

Large deformation, instabilities, damage and
activity in soft materials
Shengqiang Cai
Mechanical and Aerospace Engineering
University of California, San Diego
Extremely Stretchable and Tough Gels
Water >95 wt%: maintain most chemical/physical properties of
water, yet it is a solid
Fracture toughness of the hydrogel
is comparable to tire rubber!
We can make even better gels
Add a tiny amount of electrospun polymer nanofibers
We can make even better gels
Make gel porous: accelerate its kinetics
0 min
40 s
0 min
30 min
Novel Applications of Gels (1)
Use gel layer to cool down a structure
Shuang Cui et al, Bio-inspired Effective and Regenerable Building Cooling
Using Tough Hydrogels, Applied Energy,2016
Novel Applications of Gels (2)
Stretchable and transparent ionic diode
Ionic logic gate
Light-induced large deformation in LCE
Light on
light
Liquid crystal elastomer + CNTs
Light off
Walking robot driven by light
Mechanochromatic Films
Stretch-Induced Color Change
Self-healing in Liquid Crystal Elastomer
Liquid crystal elastomer can be self-healable
UV illumination
Strain=100%
Strain=200%
Voltage-induced deformation in DEs
Biomimetic bilayer DE devices
Voltage off
Voltage on
Fundamental mechanics of soft materials
Creasing in an elastomer under severe compression
Fundamental mechanics of soft materials
Wrinkles in an elastomer covered by a stiff thin film
Mechanical characterization of soft materials
Puncture of cartilage for assessment of local fracture toughness
Conclusions
1.  Mechanics may play an central role in designing
new soft materials with unusual properties such as
high toughness and high stretchability, and
exploring new applications of soft materials.
2.  Synthesis of new soft materials stimulates many
exciting applications such as soft robots, iontronics,
and artificial muscle etc.
3.  New models and techniques need to be developed
for mechanical characterization of soft materials.