“…Both 2D biaxially and 2D triaxially braided composites fulfil the definition of orthotropy as long as no unsymmetric fiber rearrangement occurs during loading. The experimental results reported in [37] reveal only slight nonlinearities when the braided layer was loaded in the fiber direction. However, pronounced nonlinear behavior was observed for off-axis loading and shear.…”
The impact behavior of carbon fiber epoxy bumper brackets reinforced with 2D biaxial and 2D triaxial braids was experimentally and numerically analyzed. For this purpose, a phenomenological damage model was modified and implemented as a user material in ABAQUS. It was hypothesized that all input parameters could be determined from a suitable high-speed test program. Therefore, novel impact test device was designed, developed and integrated into a drop tower. Drop tower tests with different impactor masses and impact velocities at different bumper bracket configurations were conducted to compare the numerically predicted deformation and damage behavior with experimental evidence. Good correlations between simulations and tests were found, both for the global structural deformation, including fracture, and local damage entities in the impact zone. It was proven that the developed phenomenological damage models can be fully applied for present-day industrial problems.
“…Both 2D biaxially and 2D triaxially braided composites fulfil the definition of orthotropy as long as no unsymmetric fiber rearrangement occurs during loading. The experimental results reported in [37] reveal only slight nonlinearities when the braided layer was loaded in the fiber direction. However, pronounced nonlinear behavior was observed for off-axis loading and shear.…”
The impact behavior of carbon fiber epoxy bumper brackets reinforced with 2D biaxial and 2D triaxial braids was experimentally and numerically analyzed. For this purpose, a phenomenological damage model was modified and implemented as a user material in ABAQUS. It was hypothesized that all input parameters could be determined from a suitable high-speed test program. Therefore, novel impact test device was designed, developed and integrated into a drop tower. Drop tower tests with different impactor masses and impact velocities at different bumper bracket configurations were conducted to compare the numerically predicted deformation and damage behavior with experimental evidence. Good correlations between simulations and tests were found, both for the global structural deformation, including fracture, and local damage entities in the impact zone. It was proven that the developed phenomenological damage models can be fully applied for present-day industrial problems.
“…The strain rate behavior of 2D biaxial and triaxial braided composite was examined by Böhm et al. 41 Five braid geometries were examined, three 2D biaxial braids and two 2D triaxial braids. Biaxial braids were manufactured with braiding angles of 30°, 45°, and 70° while triaxial braids were manufactured using 30° and 45° braiding angles.…”
Section: Optical Strain Measurement For Braided Compositesmentioning
confidence: 99%
“…Secondly, the ability to use a single camera for 3D DIC measurement and high-speed imaging drastically reduces the amount of data required for this measurement. 41 Figure 8.Example 3D braided composite demonstrating the complex yarn geometry.…”
Section: Optical Strain Measurement For Braided Compositesmentioning
Braiding is an advanced textile manufacturing method that is used to produce two-dimensional and three-dimensional components. Unlike laminated structures, braids have interlaced yarns that form a continuity between layers. This structure allows for improved impact resistance, damage tolerance, and improved through-thickness reinforcement. Despite the numerous advantages of braided composites, braids also have shortcomings. Their highly complex fiber architecture presents challenges in the availability and choice of the strain measuring and characterization techniques. Advanced measurement methods such as optical strain measurement, micro-computed tomography, and in situ strain measurement are required. Optical strain measurement methods such as digital image correlation and high-speed imaging are necessary to accurately measure the complex deformation and failure that braided composites exhibit. X-ray-based micro-computed tomography measurements can provide detailed geometric and morphologic information for braided structures, which is necessary for accurately predicting the mechanical properties of braided structures. Finally, in situ strain measurement methods will provide detailed information on the internal deformation and strain that exists within braided structures. In situ sensors will also allow for in-service health monitoring of braided structures. This paper provides a detailed review of the aforementioned sensing technologies and their relation to the measurement of braided composite structures.
“…The braid angle greatly affects the mechanical properties of composite braids, and many studies have examined its effect on the mechanical performance of braided composites [13,14,15,16,17,18,19]. Previous studies have established that an increase in braid angle is accompanied by a decrease in tensile strength [20,21], peak failure load [22,23] and tensile modulus [23,24],…”
This article examines the effect of braid angle on the mechanical performance of carbon-epoxy braided tubes in tension and compression. Vacuum-assisted resin transfer moulding is used to produce a variety of tubes with several combinations of 15◦and 20◦ braid angles. As uniaxial tensile testing of cylindrical tubes is not trivial, two tensile testing fixture designs are explored. It is found that a combination of mechanical and adhesive gripping produces repeatable fractures between the grips, with no slipping. Tubes with lower braid angles exhibit higher strengths both in tension and compression, as well as absorbing greater amounts of energy in compression.
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