Papers by Keyword: Push-Out

Abstract: This experiment is to investigate delamination damage of carbon/basalt/epoxy hybrid composites on the drilling manufacturing process. The damage is caused by drilling on wet and dry conditions with a twist drill size of 8 [mm], and 10 [mm] have been conducted. This experiment was carried out based on the ASTMD 5470-12 standard. Three hybrid composites have been manufactured for samples such as H₁, H₂, and H₃. Additionally, the carbon fibers reinforced epoxy composites (CFRP) and basalt fibers reinforced epoxy composites (BFRP) as experiment control had built. The aim is to assess the defect zone of carbon/basalt hybrid composite against the drilling. The examination results showed that the feed rate speed of various laminate configurations e.g., H₁, H₂, and H₃, on drilling dried between twist drill of 10 [mm] and 8 [mm] diameters are 50.5 %, 25 %, and 33.2 %, respectively. Also, adding lubricant during the drilling work has reduced peel-out and push-out effectively. The delamination defect has been the high resulted in drilling using drill 10 [mm] in wet or dry conditions. In contrast, delamination defect has occurred minimum on drilling hole using twist drill 8mm in work wet and dry condition. It has still occurred. From this research, the combination sequence of basalt and carbon fiber has the possibility to experience the delaminate damage in dry drilling processes.

Abstract: Through the development of new metal matrix composites, the specific strength and stiffness can be increased above the level of conventional light metal alloys and increase their potential for lightweight applications. The composite extrusion process is a promising manufacturing method for reinforced light metal extrusions. Particularly, the reinforcement with ceramic fibers can increase both the specific strength and stiffness which are essential for lightweight purposes. To exploit the full potential of the reinforcement, the interface of this MMC has to be optimized regarding the load transfer between matrix and fiber and therefore has to offer a strong bonding. In this contribution a hybrid composite is produced by using an Al₂O₃-fiber/AlMg0.2 composite wire which is embedded in an EN AW-6082 extrusion profile. Both the characterization of the interface and determination of the influence of processing and heat treatment are presented. For that purpose, the composites are characterized qualitatively by metallographic analysis and quantitatively by micro push-out testing of the ceramic fibers prior and after composite extrusion. To investigate the influence of additional heat treatment the state as fabricated, which equals a T4 state of the matrix material, as well as a T6 state with additional solution annealing and artificial ageing are compared. It was found that the extrusion process has a beneficial influence on the microstructure and the mechanical interface properties and therefore confirms applicability of composite extrusion for manufacturing of alumina reinforced profiles. The heat treatment however showed no significant influence on the embedded composite wire and its interface properties.

Abstract: Unidirectional SiC/SiC minicomposites were produced by infiltration of a Hi-Nicalon fibre tow by using pulsed chemical vapour deposition (P-CVD). The sequence of precursor gazes inlet steps determines the structure of the Pyrocarbon/TiC layered interphase deposited first on the filaments. The SiC matrix is then deposited with a given thickness. The different interphase structures will be described. The interface behaviour was characterized by indentation method. The load is applied on the fibre-end at a polished cross-section of the composite, and the displacement of that fibre-end is measured. The push-in test on thick specimens shows that the fibre debonds at a given fibre stress and then slides under a certain frictional shear stress. Both parameters increase when the TiC layers become discontinuous, like aligned TiC clusters in a Pyrocarbon matrix. The load-displacement behaviour is in very good agreement with theory when the interfacial shear stress is kept constant, non depending on relative slip displacement. The push-through test on thin composite slices gives directly access to sliding resistance because the fibre is less compressed. The load displacement curves obtained will be described and analysed. For example, sliding velocity jumps revealed a slight increase in sliding resistance with velocity. During push-back, a seating drop was recorded as the fibre returns in its initial position, illustrating a certain effect of roughness.