Analytical investigation of fiber-orientation dependent stresses in a thick stiffened fiber-reinforced composite beam on simple supports

Meccanica ◽  
2017 ◽  
Vol 53 (4-5) ◽  
pp. 1049-1069 ◽  
Author(s):  
S. Reaz Ahmed ◽  
A. A. Mamun
Author(s):  
Antony Paul ◽  
Jeffery M. Gallagher ◽  
Raymond J. Cipra ◽  
Thomas Siegmund

Fiber reinforced composite materials are now frequently being used over conventional materials for their ability to achieve tailored properties and performance characteristics. With the recent advancements in manufacturing techniques, short-fiber composites are coming into prominence in this sector, with their cost advantage and their capability for large throughput. Randomness of fiber orientation is inherent to short fiber composite manufacturing processes. In order to effectively manipulate the mechanical properties of a short-fiber reinforced composite, it is imperative to adequately control the orientation of the fibers during the deposition stage. A process is currently developed to acquire geometrical data of the target object and to utilize it to create a short-fiber reinforced component with controlled fiber orientation. The topological data acquisition of the object is made possible using non-contact 3D imaging techniques. The geometric data is then transferred to a commercial CAD package for the added capability to manipulate the geometry as may be required for specific applications. Subsequently, geometric data constitutes the basis of path planning for the tooling processes. In our process, a novel rapidly re-configurable tooling and molding technology is employed by which a 6-axis robotic arm is used to sculpt a pin-device vacuum surface. After the tooling is completed, the robotic arm will use a deposition nozzle to orient a steady stream of initially random short-fiber from a feeder into a unidirectional output, onto the tool surface. By controlling the position and orientation of the deposition nozzle, it is possible to control the orientation and density of fiber in each section of the near-net shaped composite pre-form. The fiber pre-form is then impregnated with a suitable matrix medium and cured to create the required component. The outlined process is thus capable of manufacturing a near-net shaped short-fiber reinforced component with highly specific mechanical properties. One of the many applications envisaged using this process is the manufacture of custom form-fitting braces, masks and guards for use in healthcare products. A patient intervention can have his or her features acquired using stereo-imaging and have corrective measures incorporated into the device prior to manufacturing. By controlling the orientation and density of the fiber at different portions of the device, it is possible to provide adequate support at specific areas or to restrict movement in specific directions while providing compliance to movement in the others.


1998 ◽  
Vol 7 (4) ◽  
pp. 096369359800700 ◽  
Author(s):  
VK Ganesh ◽  
S Ramakrishna ◽  
HJ Leck

A method of fabricating fiber-reinforced composite based functionally gradient material is described in this paper. The material has continuously varying mechanical properties along the length. The continuous variation of the mechanical properties is achieved by continuously varying the fiber orientation using the braiding process. The test results indicate an elastic modulus increase by about 42% from the largest braid angle to the smallest braid angle for the material system and the orientation angle considered in the present study.


2014 ◽  
Vol 887-888 ◽  
pp. 1246-1250 ◽  
Author(s):  
Zhi Kai Li ◽  
Dong Lu ◽  
Qiang Wang ◽  
Yong Bo Wu

This work is focused on the study of orthogonal cutting of carbon fiber reinforced composite. A model based on finite element was developed. Through defining ultimate stresses of fiber tension cracking and fiber compression bucking, ultimate stresses of matrix longitudinal tensile and shear damage. Cutting forces obtained from the FE simulation matches well with the experimental observations. Than analysis cracking and crushing phenomenon of matrix in different fiber orientation, the influence of fiber orientation on sub-surface damage was studied, it shows that the cracking of sub-surface damage value increased with the increase of fiber orientation angle.


2013 ◽  
Vol 135 (6) ◽  
Author(s):  
U. Baneen ◽  
J. E. Guivant

This paper presents a method for the detection of damage present in composite beam-type structures. The method, which successfully detected damage in steel beams, is applied to a glass fiber-reinforced beam in order to verify its suitability for composite structures as well. The damage indices were obtained using the gapped-smoothing method (GSM), which does not require a baseline model in order to detect damage. Despite the advantage of avoiding the need for a reference model altogether, unavoidable measurement errors make GSM rather ineffective. The proposed method uses the damage indices that GSM provides for synthesizing a set of likelihood functions that is processed under a Bayesian approach in order to reduce the effect of the noise and other uncertainty sources. The quality of the damage detection was examined by investigating an optimal sampling size analytically, and it was demonstrated through numerical simulation. This paper details the theory of the noise suppression method based on Bayesian data fusion, includes an analysis of the optimal sampling size, and presents the experimental results for two glass fiber-reinforced composite beams with a narrow and wide delamination, respectively. A noise-addition process was applied to the simulated data considering two different noise distributions. The composite beam was modeled in ANSYS, and harmonic analysis was used to obtain the frequency response functions at different beam locations. The results were obtained by adding 5, 10, and 15% noise in the simulated data, and they were then validated from the experimental results.


Author(s):  
Adam Soto ◽  
Fariborz M. Tehrani

This paper investigates the cracking phenomena of fiber-reinforced concrete in steel and concrete composite beam systems. Various parameters contribute to the crack development and weakening of the composite system, while the concrete slab is bonded to the steel beam. The weakening can result from the longitudinal shear stress that causes cracking from shear connectors, cracking from tensile forces, crushing due to compressive forces and also cracking from concrete shrinkage. These cracks can contribute to premature failure of the composite beam. This paper investigates fiber reinforcement as a solution to decrease the amount of cracking in composite beams. The presented methodology includes experimental studies to evaluate cracking characteristics and strength of fiber-reinforced composite beams. Parameters of the study included spacing between studs, application of welded wire reinforcement, and fiber reinforcement. Results indicate the effectiveness of fiber-reinforcement in reducing crack widths and number of cracks, even though, spacing between studs and presence of welded wire were essential in crack control. Further, fiber-reinforced specimens showed higher compressive and tensile strength by 30% and 70% respectively. The deflection at the peak load also showed a 23% decrease for the specimen with hybrid fiber-wire reinforcement in comparison with the specimen reinforced with welded wire only.


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