High shear strength pultrusion
AssigneeEbert Composites Corporation
InventorDavid W. Johnson
Life of this patent
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Abstract
To produce a pultrusion which can be machined without undue strength loss bidirectional woven fiber fabric is modified to be pultrudable into a high shear strength composite member. In a preferred form of the invention the fabric is pleated in the pultrusion process to create an endless wall of stacked switchback pleated layers which defines a box beam wall in one example, and the shaft of a bolt in another. Products produced by this process have improved isotonic strength qualities over currently produced pultrusions, which are limited to unidirectional fibers, continuous fiber mats, or alternating layers of non-woven 0.degree. and 90.degree. cloth and do not have the shear strength inherent in the pleated configuration.
Claims15
A pultrusion of enhanced isotropic strength characteristics comprising:
- (a) a fiber component defining a longitudinal pultrusion direction and being comprised of:
- (I) at least one layer of bidirectional woven roving fiber cloth having
- (a) an array of transverse woof fiber tows and having at least one unfinished side edge defined at least in part by exposed fiber ends of fibers of said transverse fiber tows;
- (b) an array of longitudinally extended warp fiber tows interwoven with said woof fiber tows;
- (ii) a longitudinally extended binder layer superimposed on said layer of woven roving at least over a portion thereof adjacent said at least one unfinished side edge;
- (iii) said binder layer binding said exposed ends of fibers of said transverse fiber tows and matting same to minimize the exposure of frayed ends;
- and,
- (b) a solidified resin matrix impregnated into said fiber component to define a rigid mass having bidirectional interwoven fibers at least a portion of which has been pultruded into multiple continuous layers of bidirectional fiber cloth in a switchback pleat configuration with pleat fold lines parallel to the pultrusion direction and at least some of the fibers of said fiber cloth having substantial transverse directional components to define cross fibers such that machine cuts made into said pultrusion in a direction substantially parallel to said cross fibers are reinforced by same against longitudinal shearing forces.
A composite pultrusion comprising:
- I. a fiber cloth composite component comprising:
- (a) a bidirectional fiber fabric comprising:
- (I) a first array of spaced substantially parallel fiber bundles;
- (ii) a second array of spaced substantially parallel fiber bundles extending substantially transversely of the bundles of said first array;
- (iii) the bundles of said first array being interwoven with the bundles said second array such that substantially all of the fibers of each array are interwoven with the fibers of the other array to define an interlocked fiber grid;
- (iv) said bidirectional fabric being substantially continuous in a direction defined as the pultrusion direction and having a transverse direction substantially orthogonal to said pultrusion direction and a discrete width dimension measured in said transverse direction such that said bidirectional fabric defines two generally parallel side edges and is manifested as an elongated bidirectional fiber ribbon;
- (b) a unidirectional fiber fabric defined as a unidirectional fiber ribbon of longitudinally extended spaced fiber bundles and substantially parallel side edges;
- (c) said unidirectional fiber ribbon being overlaid onto said bidirectional fiber ribbon such that at least one of the edges of each ribbon is an aligned edge which is substantially aligned with an edge of the other of said ribbons;
- (d) positive attachment means attaching said ribbons together substantially continuously at least along a region substantially adjacent said aligned edges such that the aligned edge of said unidirectional fiber ribbon stabilizes said transverse bundles of said second array of said bidirectional ribbon against fraying;
- (e) at least a portion said bidirectional fiber fabric being configured at least in part as multiple continuous layers of bidirectional fiber cloth laid out in a switchback pleat configuration with pleat fold lines parallel to the pultrusion direction and at least some of the fibers of said fiber cloth having substantial transverse directional components to define cross fibers such that machine cuts made into said pultrusion in a direction substantially parallel to said cross fibers are reinforced by same against longitudinal shearing forces and,
- II a resin matrix integrated into the fibers of both said unidirectional fiber ribbon and said bidirectional fiber ribbon by being drawn through a die with both said ribbons and allowed to cure to produce a solid high shear strength composite mass.
A composite pultrusion defined at least in part by multiple contiguous layers of bidirectional fiber cloth in a switchback pleat configuration with pleat fold lines parallel to the pultrusion direction and at least some of the fibers of said fiber cloth having substantial transverse directional components to define cross fibers such that machine cuts made into said pultrusion in a direction substantially parallel to said cross fibers arc reinforced by same against longitudinal shearing forces.
Dependencies are inferred from the claim text.