Conformability of Flat Fabric

Fabric Forms Produce Woven and Braided fabrics from the flat tape yarn with different configurations Evaluate processing issues Characterize tensile, shear and conformability

Woven Fabric Plain Weave Twill Weave (3/1) Satin Weave (8 harness) Texture: –10 epi, 10 ppi (50/50) –10 epi, 5 ppi (67/33) –10 epi 2.5 ppi (80/20)

Braided Fabric Two braid types: –Biaxial Braid (64 carriers) –Triaxial Braid (64 carriers + 32 longitudinals) Formed at four different mandrel diameters: 4.1 cm 4.3 cm 6.1 cm 8.9 cm –Made for high coverage, braid angle results from cover factor

Woven Fabrics Warp was produced by hand. It was possible to keep the yarns flat if the supply spool was kept horizontal and rotated to prevent twist. Heddles had to be modified (flattened) to allow the yarn to stay flat during weaving. Pick insertion required pull off from the spool to prevent twisting. Some yarns split when they hit another object during weaving - heddle sides, another yarn, lease rods…

Plain Weaves Generally weave fine. Tight configuration much easier to produce (10/10) than looser ones

Twill Weaves End density was reduced rather than pick density to assist in weave production rates Difficulty maintaining quality fabric with low end count (5/10 and 2.5/10)

Satin Weaves End density reduced, not pick Sleazy fabric - difficult to handle, yarns move around

Braided Fabrics Bobbins were spooled by hand - supply of yarn was kept horizontal and rotated while winding to prevent twist buildup Composites type carriers were used with large pigtails. Generally braid formed well - at higher braid angles there was some yarn splitting Braids were formed over cylindrical mandrels and then removed

Biaxial Braided Fabrics Four different diameter mandrels were used for production When braids were removed from the mandrels, they reoriented to a stable configuration. Generally all the braids deformed to a similar shape

Biaxial Braided Fabrics

Biaxial Braided Fabrics - Relaxed Braid Angles

Triaxial Braided Fabrics The Triaxial braid is a biaxial braid that has longitudinal yarns inserted at each horn gear. 64 biaxial carriers are used plus an additional 32 triaxial (longitudinal) carriers. Braiding went smoothly, similar to biaxial. Fabrics were not removed from the mandrels for measuring braid angles

Traixial Braids - As Formed Braid Angles

Tensile Testing Ravel strip method for wovens Braid sleeve for braids

Tensile Response - Strength

Tensile Response - Strain to Failure

Tensile Response - Modulus

Tensile Response - Poisson’s Ratio

Tensile Response - Poisson

Conformability Fabrics were pressed against the surface of a sphere and the ratio of contact area to fabric area was determined. Initially a bowling ball was used, but most of the fabrics conformed perfectly. A smaller diameter sphere (bocce ball) was used to get more differentiation.

Bowling Ball test

Only the Plain Weave had noticeable folds or wrinkles Braided fabrics (small diameter mandrels) were not wide enough to get a full circle contact

Bocce Ball Test - Plain Weave

Bocce Ball Test - Satin The border of the restraining ring and the folds/wrinkles were marked for measurements later

Bocce Ball: Twill

Bocce Ball: Braid

Bocce Ball: Triaxial

Flattened Images: Plain Weave

Flattened: Twill

Flattened: Satin

Flattened: Braid

Flattened: Triaxial

Comparison of Conformability