Polymeric composites with tunable properties

A composite material having a tunable stiffness, comprising:

• an elastomeric matrix having an elastic modulus between 10 kPa and 1 MPa;
• a metallic component combined with the matrix, wherein the metallic component comprises a plurality of metal alloy particles having a diameter between 5 and 50 micrometers and a melting point that is above room temperature and no more than 62 degrees Celsius;
• a plurality of conductive fibers combined with the matrix and forming a percolative network with the metallic component;
• and
• wherein the composite material has a first Young's modulus at room temperature and a second Young's modulus when heated above the melting point of the plurality of metal alloy particles by an application of electrical energy to the composite material such that a ratio of the first Young's modulus to the second Young's modulus is between 4.33 and 5.05 inclusively.