Abstract: Systems and methods for semi-discrete modeling of progressive damage and failure in composite laminate materials are disclosed. An example method includes receiving, from a user, a fibrous strip width and a fibrous strip spacing, and creating a finite-element (FE) mesh by: generating, using a structured hex meshing algorithm, a plurality of fibrous strips along a fiber direction based on the fibrous strip width and the fibrous strip spacing, and generating, using a free hex-dominated advancing front meshing algorithm, a bulk element between each of the plurality of fibrous strips. The FE mesh may define a portion of a composite laminate material. The example method includes determining a predicted mechanical response of the composite laminate material by: generating a constitutive model corresponding to the composite laminate material based on the FE mesh, and inputting a stress value or a strain value to the constitutive model to generate the predicted mechanical response.

Abstract: Systems and methods for semi-discrete modeling of delamination migration in composite laminate materials are disclosed. An example method includes receiving a specimen geometry and a specimen stacking sequence. The example method also includes creating a finite-element (FE) mesh that defines a composite laminate material by: generating, using a mesh generation tool, a plurality of plies shaped according to the specimen geometry, and connecting the plies together based on the stacking sequence by placing cohesive elements between each adjacent pair of plies. The example method also includes determining a predicted mechanical response of the composite laminate material by: generating a constitutive model corresponding to the composite laminate material based on the FE mesh, and inputting a strain value to the constitutive model to generate the predicted mechanical response.

Abstract: Methods to increase structural performance, strength, and durability of textile-reinforced composite materials are provided. The textile reinforcement may be knitted, for example, in a flat bed weft knitting machine. The method may include pre-stressing a textile reinforcement preform by applying tension. A polymeric precursor may be introduced to the pre-stressed textile reinforcement preform. The polymeric precursor may then be cured or consolidated, followed by releasing of the applied tension to form the composite article comprising polymer and the pre-stressed textile reinforcement. In other aspects, a composite article is provided that has a pre-stressed textile reinforcement structure and a cured polymer. The textile reinforcement may be a knitted, lightweight, seamless, unitary structure.

Abstract: Methods to increase structural performance, strength, and durability of textile-reinforced composite materials are provided. The textile reinforcement may be knitted, for example, in a flat bed weft knitting machine. The method may include pre-stressing a textile reinforcement preform by applying tension. A polymeric precursor may be introduced to the pre-stressed textile reinforcement preform. The polymeric precursor may then be cured or consolidated, followed by releasing of the applied tension to form the composite article comprising polymer and the pre-stressed textile reinforcement. In other aspects, a composite article is provided that has a pre-stressed textile reinforcement structure and a cured polymer. The textile reinforcement may be a knitted, lightweight, seamless, unitary structure.

Abstract: Methods to increase structural performance, strength, and durability of textile-reinforced composite materials are provided. The textile reinforcement may be knitted, for example, in a flat bed weft knitting machine. The method may include pre-stressing a textile reinforcement preform by applying tension. A polymeric precursor may be introduced to the pre-stressed textile reinforcement preform. The polymeric precursor may then be cured or consolidated, followed by releasing of the applied tension to form the composite article comprising polymer and the pre-stressed textile reinforcement. In other aspects, a composite article is provided that has a pre-stressed textile reinforcement structure and a cured polymer. The textile reinforcement may be a knitted, lightweight, seamless, unitary structure.

Abstract: Dissociation of a macroscale version of an aramid fiber leads to the nanofiber form of this polymer. Indefinitely stable dispersions of uniform high-aspect-ratio aramid nanofibers (ANFs) with diameters between 3 and 30 nm controlled by the media composition and up to 10 ?m in length are obtained. ANFs can be processed in transparent thin films using layer-by-layer assembly (LBL) with superior mechanical performance.

Abstract: A protective device and method of design to protect against multiple blast and impact events for use in any application in which a delicate target has to be protected. The protective device for mitigating the effects of blast or impact employs a first layer having a first acoustic impedance and a second layer having a second acoustic impedance. The second acoustic impedance is different than the first acoustic impedance. The second layer is proximate to the first layer. The first layer and the second layer are chosen collectively to tune the stress waves from the blast or impact events to one or more specific tuned frequencies. A third layer of a visco-elastic material is employed having a critical damping frequency that matches one or more specific tuned frequencies to dissipate the stress waves of the blast and impact event. The third layer is proximate to the second layer.

Abstract: A protective device and method of design to protect against multiple blast and impact events for use in any application in which a delicate target has to be protected. The protective device for mitigating the effects of blast or impact employs a first layer having a first acoustic impedance and a second layer having a second acoustic impedance. The second acoustic impedance is different than the first acoustic impedance. The second layer is proximate to the first layer. The first layer and the second layer are chosen collectively to tune the stress waves from the blast or impact events to one or more specific tuned frequencies. A third layer of a visco-elastic material is employed having a critical damping frequency that matches one or more specific tuned frequencies to dissipate the stress waves of the blast and impact event. The third layer is proximate to the second layer.

Abstract: A protective device and method of design to protect against multiple blast and impact events for use in any application in which a delicate target has to be protected. The protective device for mitigating the effects of blast or impact employs a first layer having a first acoustic impedance and a second layer having a second acoustic impedance. The second acoustic impedance is different than the first acoustic impedance. The second layer is proximate to the first layer. The first layer and the second layer are chosen collectively to tune the stress waves from the blast or impact events to one or more specific tuned frequencies. A third layer of a visco-elastic material is employed having a critical damping frequency that matches one or more specific tuned frequencies to dissipate the stress waves of the blast and impact event. The third layer is proximate to the second layer.

Abstract: A protective device and method of design to protect against multiple blast and impact events for use in any application in which a delicate target has to be protected. The protective device for mitigating the effects of blast or impact employs a first layer having a first acoustic impedance and a second layer having a second acoustic impedance. The second acoustic impedance is different than the first acoustic impedance. The second layer is proximate to the first layer. The first layer and the second layer are chosen collectively to tune the stress waves from the blast or impact events to one or more specific tuned frequencies. A third layer of a visco-elastic material is employed having a critical damping frequency that matches one or more specific tuned frequencies to dissipate the stress waves of the blast and impact event. The third layer is proximate to the second layer.

Abstract: Methods to increase structural performance, strength, and durability of textile-reinforced composite materials are provided. The textile reinforcement may be knitted, for example, in a flat bed weft knitting machine. The method may include pre-stressing a textile reinforcement preform by applying tension. A polymeric precursor may be introduced to the pre-stressed textile reinforcement preform. The polymeric precursor may then be cured or consolidated, followed by releasing of the applied tension to form the composite article comprising polymer and the pre-stressed textile reinforcement. In other aspects, a composite article is provided that has a pre-stressed textile reinforcement structure and a cured polymer. The textile reinforcement may be a knitted, lightweight, seamless, unitary structure.

Abstract: Dissociation of a macroscale version of an aramid fiber leads to the nanofiber form of this polymer. Indefinitely stable dispersions of uniform high-aspect-ratio aramid nanofibers (ANFs) with diameters between 3 and 30 nm controlled by the media composition and up to 10 ?m in length are obtained. ANFs can be processed in transparent thin films using layer-by-layer assembly (LBL) with superior mechanical performance.

Abstract: A Macroscopic Bonded Joint Finite Element (MBJFE) is capable of predicting field quantities in a bonded zone of a structural joint using a limited number of degrees of freedom. The MBJFE embeds an analytical solution directly within the element. Its stiffness and load response are based on non-linear shape functions that are dependent on load character. All critical terms are formulated as functions of a dimensionless mechanical load fraction allowing for solution via an iterative, non-linear finite element solver. The MBJFE is internally adaptive to internal and external conditions such as instantaneous external loads or internal temperatures.

Abstract: A method of using a microscopic digital imaging strain gauge includes the steps of creating a mark pattern on an object surface, positioning an image sensing device over the mark pattern, magnifying the mark pattern with a magnification lens, taking a first magnified image of the mark pattern with the image sensing device, applying a load to the object surface, taking a second magnified image of the mark pattern, and utilizing a processor to calculate the strain as derived from the first and second magnified images.

Abstract: A strain gauge includes an image sensing device having a lens, a magnification lens optically coupled to the lens, a positioning mechanism connected to the image sensing device, an image capture device for receiving an image from the image sensing device, and a processor for mathematically analyzing the image received from the image capture device and to calculate strain.