Study On Mechanical Character Of Carbon Fiber/PEEK And PTFE/POM

The uniaxial time-dependent cyclic of carbon fiber/PEEK and PTFE/POM composite was studied experimentally. Three-dimensional finite element models were used to analyze the property of PTFE/POM.The thesis mainly gain the following results:The property under stress-controlled and stress-controlled loading and the ratcheting behaviors of carbon fiber/PEEK composite were discussed under different conditions. It was shown that the creep behavior of carbon fiber/PEEK composite is better than that of PEEK. In the experiment of strain-controlled cyclic, the stress amplitude has a close relationship with the applied strain loading rate and strain amplitude. Due to the stress relaxation, the responded stress amplitude will decreases as the hold time at strain peak increase. The ratcheting occurs in the composite to asymmetrical stress-controlled, and the ratcheting strain depends on the stress amplitude and stress loading rate. The stress holding time and low loading rate lead to an increased ratcheting strain. The carbon fiber will fail as the peak holding time beyond the range.The ratcheting behaviors of PTFE/POM is similar to carbon fiber/PEEK composite’s. But it was shown that the creep and stress relaxation was obvious during the experiment.The results of finite element analysis for property of PTFE/POM is:(1) The volume fraction of the carbon fiber has a great effect to the strength of the composite. When the volume fraction is10%, we can gain the most similar curve to the experiment’s.(2) The ratcheting strain depends on the stress amplitude and mean stress.(3) Although there is some diversity between experiment and finite element analysis, the results of simulation can make a appropriate prediction for the character of ratcheting.