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.

The present invention applies to a molding method for a fiber-reinforced plastic structure having an internal cavity. Firstly, grain groups, which mainly consist of a plurality of high-rigidity grains, are accommodated in bags, and a plurality of cores are formed. A reinforcing fiber substrate, is placed between the plurality of adjacent cores so as to be interposed therebetween. For example, a plurality of molding base materials are prepared by surrounding each core with a prepreg, and the plurality of molding base materials are combined and placed inside a molding die, and the molding base materials are compression molded. When compression molding, a part of the outer surface of the cores is locally pressurized, and the internal pressure of the cores is increased, changing the shape thereof, thus eliminating voids that are present between the cores and the prepreg and/or the prepreg and the molding surface of the die.

The present invention applies to a molding method for a fiber-reinforced plastic structure having an internal cavity Firstly, grain groups, which mainly consist of a plurality of high-rigidity grains, are accommodated in bags, and a plurality of cores are formed. A reinforcing fiber substrate, is placed between the plurality of adjacent cores so as to be interposed therebetween. For example, a plurality of molding base materials are prepared by surrounding each core with a prepreg, and the plurality of molding base materials are combined and placed inside a molding die, and the molding base materials are compression molded. When compression molding, a part of the outer surface of the cores is locally pressurized, and the internal pressure of the cores is increased, changing the shape thereof, thus eliminating voids that are present between the cores and the prepreg and/or the prepreg and the molding surface of the die.

A method of manufacturing a composite vessel assembly (20) includes the steps of filling a first chamber defined by a first liner (28,30,32) with a first granulated material (96) through a first orifice (98) in the first liner. A vacuum is then applied to the first chamber, and the first orifice is plugged. The first liner may then be enveloped with a first layer (84) for structural rigidity followed by relief of the vacuum.

A method of manufacturing a composite vessel assembly (20) includes the steps of filling a first chamber defined by a first liner (28,30,32) with a first granulated material (96) through a first orifice (98) in the first liner. A vacuum is then applied to the first chamber, and the first orifice is plugged. The first liner may then be enveloped with a first layer (84) for structural rigidity followed by relief of the vacuum.

A method for molding fiber-reinforced plastic. A core is formed in a desired shape by accommodating, in a flexible bag, a grain group containing plurality of grains. The core is placed inside a prepreg containing resin and fibers, and the prepreg, in which the core is housed is placed in a molding die and compression molded. When doing so, the grain group contains first and second grains (a,b) that satisfy the equation (1). (1) 1.1(Da/Db)2.0 In the equation Da is the grain diameter of the grains (a), and Db is the grain diameter of the grain (b). When using a molding die to mold a molded article having a cavity, the above mentioned molding method enables an increase in the internal pressure of the core in order to change the peripheral surface area of the core, without using a pressurized gas and/or pressurized liquid.

A method for molding fiber-reinforced plastic. A core is formed in a desired shape by accommodating, in a flexible bag, a grain group containing plurality of grains. The core is placed inside a prepreg containing resin and fibers, and the prepreg, in which the core is housed is placed in a molding die and compression molded. When doing so, the grain group contains first and second grains (a,b) that satisfy the equation (1). (1) 1.1(Da/Db)2.0 In the equation Da is the grain diameter of the grains (a), and Db is the grain diameter of the grain (b). When using a molding die to mold a molded article having a cavity, the above mentioned molding method enables an increase in the internal pressure of the core in order to change the peripheral surface area of the core, without using a pressurized gas and/or pressurized liquid.

Lightweight and strong components having any desired shape, form, or geometry may be manufactured using thermally expanding mandrels by the processes described herein. A thermally expanding mandrel may be formed from an expanding material composition including thermally expanding particles, e.g., micronized rubber particles, and water-soluble binder material, e.g., gypsum plaster. Component material may be applied to the mandrel, and the mandrel may be inserted into a molding tool. Upon application of heat to the mandrel, the mandrel may expand, and compress and cure the component material into a component within the molding tool. Following formation of the component, the mandrel may be washed out of the component, e.g., using pressurized water, and the expanding material composition may be recycled and/or reused.

Lightweight and strong components having any desired shape, form, or geometry may be manufactured using thermally expanding mandrels by the processes described herein. A thermally expanding mandrel may be formed from an expanding material composition including thermally expanding particles, e.g., micronized rubber particles, and water-soluble binder material, e.g., gypsum plaster. Component material may be applied to the mandrel, and the mandrel may be inserted into a molding tool. Upon application of heat to the mandrel, the mandrel may expand, and compress and cure the component material into a component within the molding tool. Following formation of the component, the mandrel may be washed out of the component, e.g., using pressurized water, and the expanding material composition may be recycled and/or reused.

The invention relates to a method and a molding core for producing a fiber composite component (34), in particular in aerospace, comprising the following method steps: introducing a core sleeve (9) into a molding tool (2) for establishing an outer geometry of a molding core (27) to be formed; filling the core sleeve (9) that is introduced with a vacuum-fixable filling material (21); applying a vacuum to the core sleeve (9) and consequently vacuum-fixing the filling material (21) for forming the molding core (27); and at least partly laying at least one semifinished fiber product (33a, 33b) on the molding core (27) that is formed, for the shaping of the fiber composite component (34) to be produced.