Abstract: An automated fiber lay-up machine for the fabrication of reticulated structures comprising an upper carriage (12) which carries a fibrous material handling system (14), including a source of resin (78), and a lower carriage (44) which carries a fiber laying head (46). The upper and lower carriages each have a selected number of degrees of freedom of movement to allow positioning of the fibrous material handling system and the fiber laying head. Means (20, 32, 50, 60, 113) are provided to move and control the motion of the upper and lower carriages. The movement of the upper carriage is slaved to the movement of the lower carriage to allow the fibrous material handling system to dispense the fibrous material to the fiber laying head. The fiber laying head can rotate to provide an extra degree of freedom and can also be independently moved normal to a work surface.

Abstract: This invention is directed to a method of automatically controlling curing of a thermosetting polymeric material. The method comprises the steps of (a) applying heat to the polymeric material to initiate curing; (b) measuring a selected characteristic of the polymeric material at various times during the cure cycle thereof; (c) generating a set of signals corresponding to the measurements made; (d) determining from the signals the optimum time for applying pressure to the polymeric material; and (e) automatically applying pressure to the polymeric material at the optimum time, in a closed-loop system. The selected characteristic measured may be the capacitance or the dissipation of the polymeric material. In general, the pressure is automatically applied immediately after the minimum capacitance level is reached but before hardening of the polymeric material.

Abstract: An automated lay-up machine for the fabrication of composite structures comprising an upper carriage (12) which carries a material handling system (14) and a lower carriage which carries a laying head (46). The upper and lower carriages each have a selected number of degrees of freedom of movement to allow positioning of the material handling system and the laying head. Means (20, 32, 50, 60, 145) are provided to move and control the motion of the upper and lower carriages. The movement of the upper carriage is slaved to the movement of the lower carriage to allow the material handling system to dispense material to the laying head. The material handling system and the laying head can also rotate to provide an extra degree of freedom, with the rotation of the material handling system also being slaved to the rotation of the laying head. The laying head can also be independently moved normal to a work surface.

Abstract: The invention is directed to an apparatus and method for curing polymeric materials by use of a closed-loop, automatic process control technique. A dielectric monitoring device (15) senses the electrical characteristics which are analogous to viscosity changes taking place in an uncured or partially cured polymeric material (10) while heat is applied thereto. The generated analog signal, which changes in response to variations in the capacitance and dissipation of the polymeric material, is fed into a microcomputer (21) which determines from the direction and amplitude of the generated wave form both the maximum and minimum levels of capacitance and dissipation developed. When a predetermined condition is reached, the microcomputer (21) sends a control signal to processing equipment (24,25) to apply pressure, heat and/or vacuum to the polymeric material (10) at or near the onset of gelation but prior to the hardening point.

Abstract: A resinous material suitable for the fabrication of laminated structures comprising a first layer of resin and at least one second layer of filled resin contiguous with the first layer, the second layer being flowable under a compressive force. In the manufacture of a reticulated laminated structure of substantially uniform thickness, the thickness of the second layer varies in accordance with the number of first layers overlying one another at crossover nodes in the reticulated structure, with the second layer flowing from between the plies of the first layer at the nodes due to compressive forces applied to achieve such substantially uniform thickness.

Abstract: The invention relates to a method and apparatus for making hollow, resin-impregnated fibrous fabric articles. Specifically, it relates to a method wherein a reusable mandrel is made sufficiently rigid to receive a lay-up of the article to be manufactured. The rigidized assembly is placed within a female mold, derigidized and expanded to apply pressure from within, thereby forcing the lay-up against the interior of the mold. Heat is applied to cure the resin, producing an article having a very high degree of dimensional accuracy.

Abstract: An improved manufacture including a fiber-reinforced epoxy composite joint, and the method for producing same, in which the fibers of each of the composite adherends pass through and are intermeshed across the joint bondline. A scarfed mating surface is prepared on the end of each of the adherend elements-to-be-joined, after which a chemical etching of the mating ends to obtain exposed lengths of filaments or fibers is provided. A sheet of unsupported adhesive material is inserted between the scarfed and etched mating surfaces prior to their layup, after which heat and pressure are applied for bonding the joint. The exposed fibers of each element cross the bondline to intermesh with those of the other element during the melting of the unsupported adhesive. This process increases the joint efficiency to 83% of the efficiency of a non-joined element.

Abstract: A method is disclosed for fabricating in a single stage hollow polymeric article of manufacture from a flexible fibrous material, regardless of the degree of complexity of the laminate. The material is applied to a hollow flexible envelope which includes a pattern of any degree of complexity and which is supported on a solid mandrel, to be encased in a two-part female die. The envelope and applied material are sealed off from the mandrel by means of film layers forming a bag. A vacuum is established within the bag, resulting in forces acting from the inner side of the envelope through it and the laminated material against the die walls. The support mandrel is removed, and the remaining assembly is cured under the vacuum with or without elevated pressures. After cooling, the die and envelope are readily removed from the article.