Papers by Keyword: Interfacial Strength

Abstract: Carbon Fiber Reinforced Thermoplastics (CFRTP), which have a short production cycle time and high specific strength and stiffness, are focused on in the automobile industry. Generally, the mechanical properties of FRP are affected by the interfacial strength between the reinforcing fiber and matrix, so the control of the interfacial strength between the reinforcing fiber and matrix is important. Compared to CFRP with epoxy resin, the interfacial strength between the reinforcing fiber and matrix of CFRTP is relatively low. Recently, a method to improve the interfacial strength between the reinforcing fiber and matrix by grafting Carbon Nanotube (CNT) on the carbon fiber has been developed. In this study, the bending properties of CFRTP laminates using CNT grafted plain woven carbon fiber fabric were clarified. Bending strength of CFRTP laminates using CNT grafted plain woven carbon fiber fabric were higher than that using as-received plain woven carbon fiber fabric.

Abstract: Carbon fiber reinforced thermoplastics (CFRTP) are expected to be used as a structural material for aircraft and automobiles not only for their mechanical properties such as high specific strength and high specific rigidity but also for their high recyclability and short molding time. Generally, in a composite material having a laminated structure, interlaminar delamination is often caused by an out-of-plane impact, so the interlayer property plays an important role in the mechanical properties. It has been reported that the fiber/matrix interfacial strength increases by grafting carbon nanotubes (CNT) on the carbon fiber surface. In this study, CNT grafted carbon fibers were used for reinforcement of CFRTP laminate for the improvement of impact properties of CFRTP laminates. The impact absorbed energy of the CFRTP laminate using CNT grafted carbon fibers as reinforcing fiber was higher than that using untreated CF.

Abstract: In the present study interfacial characteristics of carbon nanotubes (CNTs) and their composite with different types of defects are calculated using molecular dynamics (MD) simulation. Although single-walled CNTs (SWCNTs) are found to have ultra-high stiffness and strength, an enormous scatter is also observed in available experimental results due to the presence of nanoscale defects such as vacancy and Stone-Wales defects. The current paper investigates the influences of Stone-Wales (S-W) and vacancy defects on the mechanical properties of composites containing defective CNTs.

Abstract: Ramie fibres were surface treated in order to enhance the interfacial interaction between ramie natural fibres and vinyl resin matrix. The fibres are exposed to three different treatment ways in this paper. The surface topography and binding force influenced by the treatments were characterized by contact angle and mechanical property. Single fibre pull-out tests combined with SEM characterization of the fracture surfaces were used to identify the interfacial strengths and to reveal the mechanisms of failure.

Abstract: In this study, interfacial shear strength of carbon fiber reinforced polypropylene were investigated. Two kinds of reinforcements are used. One is non-treated carbon fiber, another is acetone-treated carbon fiber. And two kinds of matrices are used. One is non-treated polypropylene, another is maleic anhydride-polypropylene. Three point flexural tests and micro debonding tests are conducted. As a result, following conclusions are obtained. Acetone treatment and maleic anhydride are effective to the adhesives on the surface between fiber and matrix. But simultaneous treatments are not effective. The shear strength is not dependent on fiber embedded length. The contact angle and fracture load are dependent on fiber embedded length. The interfacial strength is dependent on the contact angle. As the contact angle increases, the interfacial strength increases.

Abstract: The casting WC particles reinforced steel matrix composite coatings on Cr15 steel substrate were fabricated using the vacuum infiltration casting technique, meanwhile, investigated the relationship between the structure, hardness and the volume fraction of tungsten-iron powder in the composite coatings. The fabricated composite coatings contained tungsten-iron powder of 4.96, 9.31, 17.15 and 23.64 vol%, respectively. The microstructures and phase of the composite coatings were analyzed using Optical Microscope (OM), Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). The results shows that, with increase in volume fraction of tungsten-iron powder, the amount of martensite and in situ synthesized Fe3W3C have increased. The changes of the hardness in the composite coatings with the volume fraction of tungsten-iron powder, and the hardness has been improved greatly, the highest hardness value can reach HRC 65. In addition, the reacted layers have been formed around the WC particles and mainly consist of Fe3W3C, therefore, the interfacial strength is increased significantly. However, tungsten element in the matrix hampered the melting of the WC particles.

Abstract: The interface instability of the co-extrusion flow of polyethylene and polypropylene is studied experimentally in a slit geometry. This is done by introducing disturbances of controlled wave length and amplitude on three-layer symmetric (A-B-A) polymer melts and performing a series of extrudate mechanical testing. In this study variations of the mechanical properties as well as wave interlocking have been related to the conformation of the interfacial waves (IW). By investigating the growing (IW) and tensile stress of extrudate samples a relationship between interfacial instability (II) and mechanical properties of polypropylene (PP) and high density polyethylene (HDPE) has been established. It has been shown that instabilities are associated with IW, and it turns out that IW amplitude is known as a mechanism for controlling the strength of three layer polymer products. It is shown that the mechanism of interfacial strength is related to interfacial instabilities and the interfacial wave interlocking.

Abstract: In this research, an experimental apparatus has been developed for observing interfacial stability and deformation of multilayer pressure driven channel flows. The interface instability of the co-extrusion flow of polyethylene and polypropylene is studied experimentally in a slit geometry. This is done by introducing disturbances of controlled wave length and amplitude on three-layer symmetric (A-B-A) polymer melts as well as performing a series of extrudate mechanical testing. In this study variations of the mechanical properties as well as wave interlocking have been related to the conformation of the interfacial waves (IW). By investigating the growing (IW) and tensile stress of extrudate samples a relationship between interfacial instability (II) and mechanical properties of polypropylene (PP) and high density polyethylene (HDPE) has been established. It has been shown that instabilities are associated with IW, and it turns out that IW amplitude is known as a mechanism for controlling the strength of three layer polymer products. It is shown that the mechanism of interfacial strength is related to interfacial instabilities as well as the interfacial strength. By considering that the instability is controlled by its dominant mode. It is shown that there is ability to forecast the quality of final products in co-extrusion process.

Abstract: Spherical impact indentation tests with different impact angles (90°, 60°, 45°, and 30°) were carried out to understand the impact resistance and interfacial adhesion of zirconia (ZrO2) ceramic coating on steel and aluminum substrates, respectively. A linear rail with an adjustable impact angle was used to guide the slipping impact head to impact the specimen. It is found that the peak impact force for surface damage decreases but the contact indentation becomes longer with decreasing impact angle. Under almost the same peak impact force, the smaller the impact angle, the higher the impulse. The experimental results indicate that the ZrO2 coating on steel substrate has higher impact resistance than that on the aluminum substrate. The cross bonded test results show that ZrO2 coating on both steel and aluminum substrates exhibit excellent interfacial tensile and shear strength.

Abstract: Adhesives are widely used in our life and industrial world. However, it is difficult to characterize their mechanical properties because those strongly depend on environmental and mechanical conditions such as temperature, humidity or strain rate. In this paper, we focus on the strain rate dependence of the interfacial strength and investigate the interfacial strength by peel tests under several peel rates. The results show that, in lower rate region (under 1.0 mm/s), the interfacial strength is constant and, in transition region (1.0 to 10 mm/s) the interface strength increased with the peel rate. In middle rate region (10 to 103 mm/s), the interfacial strength is constant again. Over 103 mm/s region, the interfacial strength drops and became lower than those in middle rate cases. From the observation of peeling front by a high speed video camera, the deformation behavior of adhesives changes with the peel rate.􀀁Finite element analysis by using cohesive zone model is also conducted, and influence of the rate dependency of adhesive and base material is discussed.