| With the advantages of light texture,high strength and high rigidity,carbon fiber composites have become the focus of attention in the fields of aerospace,military engineering,medical equipment,etc.Carbon fiber composite manipulators have great potential of research value and practical value because they are more than 50% lighter than the conventional material manipulators,but still maintain the same mechanical strength.Carbon fiber composite materials can be used in the space station's robotic manipulators,robot manipulators and other fields.In this paper,the design and mechanical properties of carbon fiber-modified epoxy composite manipulators were studied and analyzed.In this study,epoxy resin was modified with cyanate resin.Based on different ratios,there were four resin formulations: #20,#40,#60,#80.During rotational rheometer experiment,the viscosity of the cyanate ester modified epoxy resin began to drop sharply when the temperature reached 60°C.This provides the basis for the wet winding process.The wettability of the modified resin and M55 JB carbon fiber was analyzed by contact angle meter.Good wettability was showed when the contact angle was about 30°.The results of the interface strength test showed that the composites had good compatibility.Four types of modified resins were analyzed by dynamic mechanical analyzer(DMA).The results showed that the glass transition temperatures of #20,#40,#60 and #80 were 170°C,176°C,224°C and 209°C,respectively.The glass transition temperature order sorted from low to high was #20<#40<#80<#60;#60 had the highest degree of crosslinking.Differential scanning calorimetry(DSC)analysis showed that #60 resin could effectively improve the shelf life of co-curing system.The resin castings were then prepared using four resin formulations.The mechanical properties of resin castings were analyzed through tensile test at room temperature.The final selection of #60 resin was made for the composite manipulator.At the same time,the curing cycle of the composites was determined: heated at 120°C for two hours and then heated at 180°C for 4 hours.The composites were prepared by wet winding.The basic mechanical properties of the composites were obtained through tensile,flexural and torsion tests,etc.Then,based on the design criterion of composite manipulators and the requirement of weight reduction optimization,the composite manipulator was designed and fabricated by grid reinforcement.The model of the manipulator was established,and the tensile,flexural and torsional properties of the composite manipulator were analyzed by finite element software ABAQUS.The tensile modulus,flexural modulus and torsional modulus were obtained as well.Meanwhile,the damage to the composites was also analyzed by finite element analysis.The results showed that the composite manipulator met the design requirements and there was no damage to the composites.By comparing with the experimental data,it can be seen that the results of the finite element analysis can provide a strong reference.The finite element analysis of the dynamic mechanical properties(such as modal shape and modal frequency)of the composite manipulator was carried out,obtaining the natural frequency of the composite manipulator at 420.29 Hz.Based on the modal data,the harmonic response analysis of the composite manipulator was done.The results showed that the displacement and stress of the composites reached the maximum when the simple harmonic excitation was close to the natural frequency.Finally,the finite element analysis of the random vibration of the composites showed that the power spectral density at the central axis of the manipulator reached 43.32 grms.By comparing with experimental data,it can be seen that dynamic mechanical properties of the composites obtained by using finite element analysis are more accurate. |
PDF Full Text Request