Composite tube having cobonded end fittings and method of making same
AssigneeThe Boeing Company
InventorJames R. Schnelz
Life of this patent
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Abstract
A structural member such as a strut includes a composite material tube having metal end fittings that are attached to the tube by co-bonded, double shear joints. The double shear bond joint construction reduces the residual stress on the bonds that result from mismatch of the coefficients of thermal expansion of the composite tube and the metal end fittings. The ends of the fittings that are bonded to the tube may include a stepped profile that functions to limit the peak stresses in the bonds.
Claims29
A method of making a structural member, comprising the steps of:
- forming an inner composite tube wall portion having a first end and a second end comprising a lay-up of uncured composite material, forming comprising wrapping a plurality of uncured plies of a fiber reinforced polymer material onto a mandrel to form, a number of the plurality of uncured plies being wrapped one revolution or less around the mandrel;
- coupling a first fitting over at least a portion of the first end of the inner composite tube wall portion and curing said inner composite tube wall portion with said fitting in place;
- forming an outer composite tube wall portion comprising a second lay-up of uncured composite material over at least a portion of the inner tube wall portion and the first fitting following the coupling of the first fitting over at least a portion of the first end of the inner composite tube wall portion and curing said inner composite tube wall portion with said fitting in place;
- and,
- co-bonding the inner composite tube wall portion, the outer composite tube wall portion, and the first fitting by curing said second lay-up.
A method of making a composite aircraft strut having a metal fitting, comprising the steps of:
- forming a first lay-up of uncured composite material defining an inner tube wall portion having a first end and a second end, forming comprising wrapping a plurality of uncured plies of a fiber reinforced polymer material onto a mandrel, a number of the plurality of uncured plies being wrapped one revolution or less around the mandrel;
- coupling at least a section of a metal fitting over at least a portion of the first end of the inner tube wall portion to create a fitting section and curing said inner tube wall with said metal fitting in place;
- forming a second lay-up of composite material over the first lay-up and at least a portion of the fitting section, the second lay-up defining an outer tube wall portion covering the inner tube wall portion and the fitting section;
- and,
- co-bonding the inner tube wall portion, the outer tube wall portion, and the fitting section by curing said second lay-up.
A method of making a structural member, comprising the steps of:
- forming an inner composite tube wall portion comprising a lay-up of uncured composite material, forming comprising wrapping a plurality of uncured plies of a fiber reinforced polymer material onto a mandrel, a number of the plurality of uncured plies being wrapped one revolution or less around the mandrel;
- coupling a fitting over at least a portion of an end of the inner composite tube wall portion and curing said inner composite tube wall portion with said fitting in place;
- forming an outer composite tube wall portion comprising a second lay-up of uncured composite material over at least a portion of the inner tube wall portion and the fitting following curing of said inner composite tube and said fitting;
- co-bonding the inner composite tube wall portion, the outer composite tube wall portion, and the fitting to form a joint by curing said second lay-up;
- and
- wherein the fitting includes a cylindrical wall having a tapered thickness, said tapered thickness decreasing in a direction toward said tube wall portions, and, the inner and outer tube wall portions on either side of said fitting each have a taper complementing the tapered thickness of the fitting.
Dependencies are inferred from the claim text.