Composite structure splice and method

A method for mitigating crack propagation in a composite structure, the method comprising:

• identifying a splice location for the composite structure to reduce stress in the composite structure;
• and
• forming a step lap splice at the splice location in which the step lap splice has a chevron shape in each layer of a first section that forms a first step lap pattern in the first section in which a plurality of chevrons is in the first section;
• in which the step lap splice has a counterpart shape in each layer of a second section that forms a second step lap pattern in the second section in which a plurality of counterparts is in the second section;
• and in which each layer with the chevron shape overlaps a corresponding counterpart shape for another layer in the second section to form the step lap splice.

A method for fabricating a composite structure, the method comprising:

• forming a first section for the composite structure in which the first section has a first end with a chevron shape, wherein first composite layers in the first section has a first step pattern at the first end;
• forming a second section for the composite structure in which the second section has a second end with a counterpart shape to the chevron shape and in which second composite layers in the second section have a second step pattern at the second end;
• and
• positioning the first end and the second end such that the first composite layers in the first step pattern overlap the second composite layers in the second step pattern at a splice location.

A method for fabricating a composite structure, the method comprising:

• forming a first section for the composite structure in which the first section has a first end with a chevron shape in which first composite layers in the first section have a first step pattern at the first end, and in which the chevron shape comprises a group of chevrons;
• forming a second section for the composite structure in which the second section has a second end with a counterpart shape to the chevron shape, and in which second composite layers in the second section have a second step pattern at the second end in which the first section and the second section are substantially planar;
• forming the first section and the second section into a cross-sectional shape created by a tool having an upper die and lower die;
• positioning the first end and the second end on a tool such that the first composite layers in the first step pattern overlap the second composite layers in the second step pattern at a splice location to form a lap splice joint in which at least one of a gap or an overlap is present between the first composite layers and the second composite layers such that stress is reduced at the lap splice joint and undesired wrinkling for the composite structure is reduced at the splice location;
• and
• curing the first section and the second section to form the composite structure.

A composite structure comprising:

• a first section for the composite structure in which the first section has a first end with a chevron shape and in which first composite layers in the first section have a first step pattern at the first end;
• and
• a second section for the composite structure in which the second section has a second end with a counterpart shape to the chevron shape;
• a second plurality of composite layers in the second section has a second step pattern at the second end;
• and the first end and the second end are positioned such that the first composite layers in the first step pattern overlap second composite layers in the second step pattern at a splice location.

A composite structure comprising:

• a first section for the composite structure in which the first section has a first end with a chevron shape comprised of a group of chevrons and in which first composite layers in the first section have a first step pattern at the first end;
• and
• a second section for the composite structure in which the second section has a second end with a counterpart shape to the chevron shape in which the first section and the second section have a desired cross-sectional shape and in which a second plurality of composite layers in the second section has a second step pattern at the second end;
• and the first end and the second end are positioned such that the first composite layers in the first step pattern overlap the second composite layers in the second step pattern at a splice location in which at least one of a gap or an overlap is present between the first composite layers and the second composite layers for a lap splice joint such that stress is reduced at the splice location and in which undesired wrinkling for the composite structure is reduced at the splice location.