Carbon epoxy strength

Vitahium FHS ahoy is a cobalt—chromium—molybdenum ahoy having a high modulus of elasticity. This ahoy is also a preferred material. When combiaed with a properly designed stem, the properties of this ahoy provide protection for the cement mantle by decreasing proximal cement stress. This ahoy also exhibits high yields and tensile strength, is corrosion resistant, and biocompatible. Composites used ia orthopedics include carbon—carbon, carbon—epoxy, hydroxyapatite, ceramics, etc. 

In particular, the techniques based on the termination of certain plies within the laminate has also shown promise. Static tensile tests of [30°/-30°/30°/90°]s carbon-epoxy laminates containing terminals of [90°] layers at the mid-plane show that premature delamination is completely suppressed with a remarkable 20% improvement in tensile strength, compared to those without a ply terminal. Cyclic fatigue on the same laminates confirms similar results in that the laminate without a ply terminal has delamination equivalent to about 40% of the laminate width after 2x10 cycles, whereas the laminates with a ply terminal exhibit no evidence of delamination even after 9x10 cycles. All these observations are in agreement with the substantially lower interlaminar normal and shear stresses for the latter laminates, as calculated from finite element analysis. A combination of the adhesive interleaf and the tapered layer end has also been explored by Llanos and Vizzini, (1992). 

Herszberg, I., Weller, T., Leong, K.H. and Bannister, M.K. (1996). The residual tensile strength of stitched and unstitched carbon/epoxy laminates impacted under tensile load. In Proc. 1st Australasian Congre.ss on Applied Mechanics. Melbourne, pp. 309-314. 

Figure 35. Mechanical properties of carbon-carbon epoxy-resin hybrid composites, compared with the properties of the composite skeletons before resin impregnation (61,62). The composite skeletons were prepared from Sigrafil HM 3 PAN based fiber, rigidized with a phenolic resin, and densified by four cycles with coal-tar pitch plus sulfur the carbonization temperature was 1000 C. (b) Flexural strength. (c) Interlaminar shear stress, measured with two sample thicknesses.

S. L. Phoenix, P. Schwartz, and H. H. Robinson, IV, Statistics for the Strength and Lifetime in Creep-Rupture of Model Carbon/Epoxy Composites, Composites Science and Technology, 32, 81-120 (1988). 

Michelle Leali Costa, Sergio Fraseino M. de Almeida, Mirabel Cerqueira Rezende, The influence of porosity on the interlaminar shear strength of carbon/epoxy and earbon/bismaleimide fabrie laminates. Composites Science and Technology 61 (2001),... 

Small deviations from the intended fibre orientation within a nominally unidirectional ply can reduce the mechanical strength and stiffness of continuous fibre laminates considerably, especially with aramid reinforcement. Wisnom [6] has investigated the reduction in strength caused by misalignment of unidirectional carbon fibres in XAS/914 carbon/epoxy... 

First, the effects of outdoor use on structural reinforced plastics such as glass/polyester or carbon/epoxy laminates are confined to the surface and do not often involve a serious threat to their structural integrity, unless perhaps there is a reduction in impact strength as a result of surface cracking. Fortunately carbon is a well-known UV absorber and therefore the fibres act as a good stabiUzer. The problems are mainly cosmetic. 

Immersion in water does not always have adverse effects. Sometimes the properties improve, or some properties may improve and others deteriorate. Kosuri and Weitsman [79] and Smith and Weitsman [80] conducted fatigue tests (5Hz at 74-89% ultimate tensile strength) on cross-plied AS4/ 3501-6 prepreg carbon/epoxy laminates in three conditions ... 

Sloan and Talbot [113] cathodically coupled 26-ply quasi-isotropic T300/ 934 carbon/epoxy laminate coupons to magnesium in natural Pacific sea water at 40°C for 140 days. In the uncoupled state in tapwater or natural sea water, the moisture uptake was -0.85% and calcerous deposit was 0.14% and 0.36%, respectively. For the coupled materials, the moisture uptake was -1.3% and the calcerous deposit was 16%. There was some leaching loss from the coupled material. The shear strengths in four point bend tests showed negligible degradation for the soaked samples, but a 30% reduction was measured for electrically coupled materials. This reduction was correlated to delaminations, reducing the effective specimen width by 20-40%. 

Liu K, Piggott MR, Shear strength of polymers and fibre composites, Part 2 carbon/epoxy pultrusions, Composites, 26(12), 841-848, 1995. 

Wyrick DA, Adams DF, Residual strength of carbon/epoxy materials. Composite Mater, 749-765, Aug 22, 1988. 

Adherent Technologies Inc. [8] has developed a process for the reclamation of carbon fibers from carbon/epoxy composites. It has studied the depolymerization of thermoset carbon fiber reinforced epoxy matrix composites using a low temperature (20 min at 325°Q catalytic tertiary recycling reclamation process and has been able to obtain a product with 99.8% carbon and 0.2% residual resin, with only a loss of about 8.6% in fiber tensile strength. The process can be economically viable, provided sufficient scrap feedstock is available. Possible applications for the recovered fiber include thermoplastic and thermoset molding compounds. 

Seawater aging of epoxy and vinyl ester resins reinforced with different fibers (e g. glass and carbon) has also been investigated (Narasimha Murthy et al., 2010). The experimental results have evidenced that the vinyl ester composites retain better their mechanical properties than epoxy ones in particular, the flexural strength and ultimate tensile strength (UTS) dropped by about 35% and 27% for glass/epoxy, by 22% and 15% for glass/vinyl ester, by 48% and 34% for carbon/epoxy, and by 28% and 21% for carbon/ vinyl ester composites, respectively. In contrast, the authors have shown that the water uptake of the epoxy-based composites is lower than that of the vinyl ester ones. 

Epoxy Carbon nanombes Strength/stiffness Tennis rackets Babolat... 

Fig. 8.23. Strength chart for a [0, 0°] carbon-epoxy laminate containing 60 vol % fibres, showing the maximum allowable stress in 0° direction as a function of 6 and R, the fraction of angled plies (after R, Tetlow).

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