A method for manufacturing a cured composite structure from first stringers, second stringers and a panel comprising a first side and a second side, the method includes, for each first stringer, supporting the first stringer on the first side of the panel using a substantially rigid mandrel positioned within a first cavity defined between the first stringer and the first side of the panel, for each second stringer, supporting the second stringer on the second side of the panel using a flexible mandrel positioned within a second cavity defined between the second stringer and the second side of the panel, and co-curing the first stringers, the panel, and the second stringers while each of the one or more first stringers are supported by the respective substantially rigid mandrel and each of the one or more second stringers are supported by the respective flexible mandrel.

A molding method for making a monolithic component made of C-SMC and internally including a cavity, including preparing a press including first and second half molds and movable side carriages defining a molding space, and placing a core inside the molding space. The core comprises a membrane, delimiting a containing space shaped to form the cavity, and at least one connector engaged with the membrane. The method includes wrapping a charge of material to be molded around the core, fixing the core inside one between the first and the second half molds, and filling the containing space of the membrane with a filling material. After closing the half molds, applying a molding pressure and then emptying the containing space of the filling material and, after opening the half molds, removing the core from the molded monolithic component.

The present invention provides a resin leakage prevention member 401 for use in a molding die 1000, wherein the molding die 1000 includes a lower die 200 and an upper die 100, the lower die 200 has a side member 201 and a bottom member 202, a space surrounded by the side member 201 and the bottom member 202 forms a cavity 204, the cavity 204 is configured to accommodate a resin material 20a, the side member 201 is configured to move relatively vertical to the bottom member 202, and the resin leakage prevention member 401 is disposed on a peripheral portion of an upper surface of the bottom member 202 and along an inner peripheral surface of the side member 201, thereby sealing a gap between the side member 201 and the bottom member 202 and preventing a resin from leaking from the cavity 204 into the gap.

A method for manufacturing a cured composite structure from first stringers, second stringers and a panel comprising a first side and a second side, the method includes, for each first stringer, supporting the first stringer on the first side of the panel using a substantially rigid mandrel positioned within a first cavity defined between the first stringer and the first side of the panel, for each second stringer, supporting the second stringer on the second side of the panel using a flexible mandrel positioned within a second cavity defined between the second stringer and the second side of the panel, and co-curing the first stringers, the panel, and the second stringers while each of the one or more first stringers are supported by the respective substantially rigid mandrel and each of the one or more second stringers are supported by the respective flexible mandrel.

Prior to curing a composite workpiece assembly, an expandable element can be inserted into a cavity of the workpiece assembly. The expandable element is configured to expand when a predetermined change is produced in an attribute of the element. The attribute can be a temperature of the element. The element is expanded by producing the predetermined change, and the workpiece assembly is cured while the expanded element is in the cavity, so that the expanded element applies positive pressure to inner surfaces of the cavity during curing. The expanded element can be removed from the cavity after curing. The expanded element can comprise a plurality of expandable pellets.

A vacuum bag having an expandable pleat is provided. The vacuum bag includes a first surface region, a second surface region, and a third surface region between the first and second surface regions. The third surface region can be folded to bring the first surface region into proximity of the second surface region. The vacuum bag also includes a strip having a first attaching region at a first end of the strip, a second attaching region at a second end of the strip opposite the first end, and a central region between the first and second attaching regions. The first attaching region is fixed to the first surface region, and the second attaching region is fixed to the second surface region such that when the central region of the strip is in a non-expanded state, the first surface region is contiguous to the second surface region.

A vacuum bag having an expandable pleat is provided. The vacuum bag includes a first surface region, a second surface region, and a third surface region between the first and second surface regions. The third surface region can be folded to bring the first surface region into proximity of the second surface region. The vacuum bag also includes a strip having a first attaching region at a first end of the strip, a second attaching region at a second end of the strip opposite the first end, and a central region between the first and second attaching regions. The first attaching region is fixed to the first surface region, and the second attaching region is fixed to the second surface region such that when the central region of the strip is in a non-expanded state, the first surface region is contiguous to the second surface region.

Provided is a method for manufacturing a fiber-reinforced plastic molded body by which, when a molded article having a hollow part is being molded using a molding mold, it is possible to deform the peripheral surface area of a core by increasing the pressure inside the core without using pressurized gas or pressurized fluid. A group of particles and the like including a particle group and a core block is accommodated in a flexible bag to form a core. The particle group is composed of multiple rigid particles. The core is arranged inside a prepreg containing a resin and fibers, and the prepreg including the core is arranged inside a molding mold and is molded by applying pressure.

A production method for a fiber-reinforced resin molded object is provided whereby a large apparatus is not used when molding, by heating and pressing, a fiber-reinforced resin base material that includes a matrix resin, a molded object with excellent precision and quality can be obtained, and for which work is simple.

The production method includes arranging, on an inner surface of a lower mold 3, a fiber-reinforced resin base material 1 obtained by impregnating a matrix resin into reinforcing fibers; filling a core space 5 of the mold, in which the fiber-reinforced resin base material 1 is arranged, with a powder mixture 2a that has liquidity and that includes thermally expandable microcapsules and another powder; sealing the lower mold 3 and an upper mold 4; heating at from a heat expansion starting temperature to a maximum expansion temperature of the thermally expandable microcapsules to cause the thermally expandable microcapsules to expand; and pressing the fiber-reinforced resin base material 1 against the inner surface of the lower mold 3 to produce a molded object.

A resin impregnation measurement device includes a jig and a resin impregnation sensor. The jig is formed into an inner surface shape of a protrusion of a stringer. The jig includes outer surfaces including a facing surface that is to face an inner surface of the protrusion. The resin impregnation sensor is disposed on the facing surface of the jig.