A method of forming a thinned prepreg sheet is disclosed. The method comprises providing a first precursor sheet comprising reinforcement fibers impregnated with a matrix resin in a first state. The method also comprises forming a second precursor sheet having a first thickness by cooling the first precursor sheet until the matrix resin is transformed from the first state to a second state. The method further comprises forming a crushed sheet comprising interstices having an average size by crushing the second precursor sheet, where the crushed sheet has a second thickness. The method also comprises forming the thinned prepreg sheet by heating the crushed sheet until the matrix resin is transformed from the second state to a third state. The thinned prepreg sheet has a third thickness less than the first thickness of the second precursor sheet.

Embodiments described herein relate to a composite structures or sandwiches that may have a relatively high bending stiffness and may have a relatively light weight as well as related methods of use and fabrication of the composite sandwiches. For example, a composite sandwich may include a core structure sandwiched between a two composite skins.

A reinforced composite structure that includes multiple regions of different geometric configurations connected together by a transition region. The reinforced composite structure includes reinforcement fibers on at least a portion of the transition region.

A method of making a sandwich-type composite panel having a cellulose-based core and a living hinge from a stack of material is provided. The stack includes first and second reinforced thermoplastic skins, first and second sheets of thermoplastic adhesive and a cellulose-based cellular core disposed between the sheets and the skins. A pressure is applied to the stack after heating the stack wherein the skins are bonded to the core by the sheets to form the composite panel. A portion of the composite panel is crushed at a predetermined location simultaneously with applying the pressure to locally compact and separate the cellular core at the predetermined location to form two side portions of the panel. The heated first skin stretches during the step of crushing while remaining intact between the two side portions. The skins bond together at the predetermined location to form the living hinge.

An anti-fatigue gel ground mat based on recycled sponge is disclosed, which includes a ground mat body. A beveled edge structure is arranged around the ground mat body. The ground mat body includes a surface layer, a gel layer, a recycled sponge layer, and an anti-skid layer compounded together in sequence from top to bottom. The gel layer is polyurethane solid gel. By arranging the gel layer, when the user steps on the ground mat body, the surface of the ground mat body is naturally concave to realize fatigue resistance. By arranging the beveled edge structure, the user can be prevented from stumbling, so that the safety is improved. The polyurethane solid gel is extruded in the shape of a snake to a lower surface of the surface layer through extrusion equipment, so that the use level of the polyurethane solid gel can be effectively reduced.