1991 Vol.4(3)
Display Mode： |
1991, 5(3).
Abstract:
The two-body abrasion behaviour f the newly developed austenite-bainitic ferrite dual-phase steels was studied in this paper. The results show that the dual-phase steel with good combination of high yield strength, toughness and strain-hardening ability possesses excellent wear resistance in high stress two-body abrasion system. The dual-phase structures is much more abrasion resistant than the quenched and tempered structure of the same steel at the case of equivalent hardness. It is found that the outstanding wear resistance of the dual-phase steel is attributed to its execelent combination of the high work-hardening ability and the good toughness.
The two-body abrasion behaviour f the newly developed austenite-bainitic ferrite dual-phase steels was studied in this paper. The results show that the dual-phase steel with good combination of high yield strength, toughness and strain-hardening ability possesses excellent wear resistance in high stress two-body abrasion system. The dual-phase structures is much more abrasion resistant than the quenched and tempered structure of the same steel at the case of equivalent hardness. It is found that the outstanding wear resistance of the dual-phase steel is attributed to its execelent combination of the high work-hardening ability and the good toughness.
1991, 5(3).
Abstract:
With the research method of gear meshing, the conjugate cam mechanism with a double-roller driven swinging rod is studied in this article. When the related conception in the field of gear research is extended into cam mechanisms, the essential character of the conjugate cam mechanism is revealed and a series of formulas for accurate calculation of some imprortant parameters are obtained. The result provides a necessary theoretical basis for the design, calculation and manufacture of the conjugate cam mechanism.
With the research method of gear meshing, the conjugate cam mechanism with a double-roller driven swinging rod is studied in this article. When the related conception in the field of gear research is extended into cam mechanisms, the essential character of the conjugate cam mechanism is revealed and a series of formulas for accurate calculation of some imprortant parameters are obtained. The result provides a necessary theoretical basis for the design, calculation and manufacture of the conjugate cam mechanism.
1991, 5(3).
Abstract:
This paper, first of all, goes into the mechanism of necking deformation of a sheet metal under plastic tension and, based on this using a constitutive relation in form of non-quadratic orthotropic yield function, developes a predicting method for the right-side curves in forming limit diagram of a sheet metal. In this part, the criterion coming in the instabel deformation process, the developmental state of instabel deformation process and the conditions coming in the instabel deformation state in form of localized necking lines are searched for a sheet metal under biaxial tensile stresses. In this analysis, the occurrent mechanism of necking deformation of a sheet metal is searched from the angel of minimal strain energy.
This paper, first of all, goes into the mechanism of necking deformation of a sheet metal under plastic tension and, based on this using a constitutive relation in form of non-quadratic orthotropic yield function, developes a predicting method for the right-side curves in forming limit diagram of a sheet metal. In this part, the criterion coming in the instabel deformation process, the developmental state of instabel deformation process and the conditions coming in the instabel deformation state in form of localized necking lines are searched for a sheet metal under biaxial tensile stresses. In this analysis, the occurrent mechanism of necking deformation of a sheet metal is searched from the angel of minimal strain energy.
1991, 5(3).
Abstract:
In this paper, a new method is proposed for kineto-elastodynamic (KED) analysis of planar four-bar linkages incorporation effects of the clearances in kinematic pairs, with a clearance being considered as a pseudo-element. The integrated effects of link elasticity and clearances in pairs on dynamic behavior of the linkage are discussed.
In this paper, a new method is proposed for kineto-elastodynamic (KED) analysis of planar four-bar linkages incorporation effects of the clearances in kinematic pairs, with a clearance being considered as a pseudo-element. The integrated effects of link elasticity and clearances in pairs on dynamic behavior of the linkage are discussed.
1991, 5(3).
Abstract:
The reverse simulation is a very efficient approach to optimize the technology design of forging process. It traced backward deformation way step by step, starting from final forging to obtain the best preform/initial billet. This paper presented three basic problems with respect to the reverse simulation and described the procedure to deal with them. A called continuous reverse simulation technique was produced to apply in preform design of forging in practical production. The numerical method was based on Upper Bound Elemental Tchnique(UBET).
The reverse simulation is a very efficient approach to optimize the technology design of forging process. It traced backward deformation way step by step, starting from final forging to obtain the best preform/initial billet. This paper presented three basic problems with respect to the reverse simulation and described the procedure to deal with them. A called continuous reverse simulation technique was produced to apply in preform design of forging in practical production. The numerical method was based on Upper Bound Elemental Tchnique(UBET).
1991, 5(3).
Abstract:
In this paper, a new model bearing-a three spiral oil wedge hydrodynamic bearing is presented. Analyses of this working principle have been given. Theory and experiment research have been carried out. The results show that the spiral oil wedge of the bearing is advantageous to the lubricant led into the whole bearing surface, temperature rise and dynamic behaviours are greatly improved as well. This bearing is an ideal one suitable for high speed and precise machines.
In this paper, a new model bearing-a three spiral oil wedge hydrodynamic bearing is presented. Analyses of this working principle have been given. Theory and experiment research have been carried out. The results show that the spiral oil wedge of the bearing is advantageous to the lubricant led into the whole bearing surface, temperature rise and dynamic behaviours are greatly improved as well. This bearing is an ideal one suitable for high speed and precise machines.
1991, 5(3).
Abstract:
This paper discussed the superplasticity behavior of aluminum-copper cast alloy with different amount of rate-earth element and superplastic forming test of a machine part was conducted. The results of the test showed that cast grains of the alloy added 0.009% RE were refined from 44μm to 23 μm. Aluminium-copper alloy added 0.009% RE exhibited excellent superplasticity under optimum condition of tensile deformation and the results were as follows:δ=165%, flow stress σ=11.5MPa, strain rate sensitivity exponent=0.35. The grain of alloy was refined further and continued to maintain equiaxed grain after superplastic deformation.
This paper discussed the superplasticity behavior of aluminum-copper cast alloy with different amount of rate-earth element and superplastic forming test of a machine part was conducted. The results of the test showed that cast grains of the alloy added 0.009% RE were refined from 44μm to 23 μm. Aluminium-copper alloy added 0.009% RE exhibited excellent superplasticity under optimum condition of tensile deformation and the results were as follows:δ=165%, flow stress σ=11.5MPa, strain rate sensitivity exponent=0.35. The grain of alloy was refined further and continued to maintain equiaxed grain after superplastic deformation.
COMPONENT MODE SYNTHESIS FOR DYNAMIC ANALYSIS OF FLEXIBLE MANIPULATOR ARMS WITH VISCOELASTIC DAMPING
1991, 5(3).
Abstract:
Substructure synthesis methods have been used for dynamic analysis of large structures with nonproportional and viscoelastic damping successfully. This methods, however, have not been brought up to now to dynamic analysis of flexible robot arms makes with distributed viscoelastic damping. In this paper, component mode synthesis method for dynamic analysis of flexible manipulator with distributed viscoelastic damping is presented, in which robotic manipulator system is broken up into its free-free substructures (or components). The equation size of the substructures is reduced by modal synthesis techniques. The reduced component equations are then coupled to construct the overall system equations by time-dependent compatibility matrix. Numerical results for a planar manipulator indicate that the proposed synthesis method is effective.
Substructure synthesis methods have been used for dynamic analysis of large structures with nonproportional and viscoelastic damping successfully. This methods, however, have not been brought up to now to dynamic analysis of flexible robot arms makes with distributed viscoelastic damping. In this paper, component mode synthesis method for dynamic analysis of flexible manipulator with distributed viscoelastic damping is presented, in which robotic manipulator system is broken up into its free-free substructures (or components). The equation size of the substructures is reduced by modal synthesis techniques. The reduced component equations are then coupled to construct the overall system equations by time-dependent compatibility matrix. Numerical results for a planar manipulator indicate that the proposed synthesis method is effective.
1991, 5(3).
Abstract:
The composition, mucrostructure and wear resistance of electroless deposited nickel-phosphorus alloy coatings were studied. The results showed that the alloys containing phosphorus lower than 7.0 wt% were super-satureated solid solution which precipitated Ni3P and was hardly effected by composite SiC, amorphous alloys containing phosphorus more than 7.0 wt% crystalized and formed the microstructure of Ni3P-matrix during heat treatment. The wear volume of high phosphorus alloys was higher than that of low phophorus coatings in as-deposited state, and lower in as-heated. The wear resistance of low phosphorus SiC composite coating with high hardness was superior to nickel phosphorus alloy coatings.
The composition, mucrostructure and wear resistance of electroless deposited nickel-phosphorus alloy coatings were studied. The results showed that the alloys containing phosphorus lower than 7.0 wt% were super-satureated solid solution which precipitated Ni3P and was hardly effected by composite SiC, amorphous alloys containing phosphorus more than 7.0 wt% crystalized and formed the microstructure of Ni3P-matrix during heat treatment. The wear volume of high phosphorus alloys was higher than that of low phophorus coatings in as-deposited state, and lower in as-heated. The wear resistance of low phosphorus SiC composite coating with high hardness was superior to nickel phosphorus alloy coatings.
1991, 5(3).
Abstract:
Based on the analyses for mechanism of necking deformation of a sheet metal under plastic tension, as stated on Part Ⅰ of the present paper, a new method predicting the rignt-side curves in forming limit diagram (FLD) of a sheet metal is advanced by this part of the present paper, which clearly takes the stranis at the onset of localized necking instabiligy as the limit stranins of the formed parts and employs a constitutive relation in form of non-quadratic orthotropic yield function recently proposed by the present author. In this predicting method, the Dp1=0 is used as the criterion to beginning the instable deformation process of a sheet element, tha dP1=dε2=0 is used as the conditions of the onset of localized necking lines in the biavial tension strain field, and the developmental process of instabel deformation between these two kinds of instability is minutely considered by the numerical integration. It is made known from applications on to several kinds of materials that the predicted results are in good agreement, the close degrees to the experimental data are finer than that predicted by other existing theories.
Based on the analyses for mechanism of necking deformation of a sheet metal under plastic tension, as stated on Part Ⅰ of the present paper, a new method predicting the rignt-side curves in forming limit diagram (FLD) of a sheet metal is advanced by this part of the present paper, which clearly takes the stranis at the onset of localized necking instabiligy as the limit stranins of the formed parts and employs a constitutive relation in form of non-quadratic orthotropic yield function recently proposed by the present author. In this predicting method, the Dp1=0 is used as the criterion to beginning the instable deformation process of a sheet element, tha dP1=dε2=0 is used as the conditions of the onset of localized necking lines in the biavial tension strain field, and the developmental process of instabel deformation between these two kinds of instability is minutely considered by the numerical integration. It is made known from applications on to several kinds of materials that the predicted results are in good agreement, the close degrees to the experimental data are finer than that predicted by other existing theories.
1991, 5(3).
Abstract:
The aim of this study was to analyse the cutting mechanism of engineering ceramics using the principles of fracture mechanics. With the aid of the finite element method the stress field in the vicinty of the tool tip and the cocation of primary crack occurrence were examined. The trace of crack propagation and the effect of depth of cut on the cutting process were examined by experiment for toughened ZrO2 and low purity Al2O3 ceramics. A model for the chip formation process is proposed and the conclusions based on the model were compared with results obtained by pictures taken with high speed photographic equipment during grinding.
The aim of this study was to analyse the cutting mechanism of engineering ceramics using the principles of fracture mechanics. With the aid of the finite element method the stress field in the vicinty of the tool tip and the cocation of primary crack occurrence were examined. The trace of crack propagation and the effect of depth of cut on the cutting process were examined by experiment for toughened ZrO2 and low purity Al2O3 ceramics. A model for the chip formation process is proposed and the conclusions based on the model were compared with results obtained by pictures taken with high speed photographic equipment during grinding.
1991, 5(3).
Abstract:
A mushy zone is formed in the lower part of an ingot by the showering of crystallites from the top and the free dendritic arms fused and broken from the dendrites growing on the side mold wall. The zone obstructs the inclusions to buoy up. In addition, the inclusions buoying to the upper part of the ingot can be carried down to the bottom by natural convective flow and trapped by the mushy zone. On the other hand, an equiaxed crystal zone in the bottom of the steel ingot results from the crystals coming from the sides and the growth of crystals caused by heat transfer. An interval from the beginning of pouring to the time when the velocity of convective flow becomes too low to carry any inclusions larger than tolerant ones down to the bottom is defined as critial time. Then, the size of bottom cone of inclusions is equal to that of equiaxed crystal zone formed in the critial time. In this paper, the method for determining critial time was proposed, and the numerical simulation on the formation of bottom equiaxed crystal zone was carried out. A 27Cr2Mo1V steel ingot of 68 tons in weight was studied. From the results of numerical simulation, the weight ratio of cut tail end to ingot body was 8.11%. This result corresponds with the weight ratio of 8.8% in production practice of the same ingot approximately.
A mushy zone is formed in the lower part of an ingot by the showering of crystallites from the top and the free dendritic arms fused and broken from the dendrites growing on the side mold wall. The zone obstructs the inclusions to buoy up. In addition, the inclusions buoying to the upper part of the ingot can be carried down to the bottom by natural convective flow and trapped by the mushy zone. On the other hand, an equiaxed crystal zone in the bottom of the steel ingot results from the crystals coming from the sides and the growth of crystals caused by heat transfer. An interval from the beginning of pouring to the time when the velocity of convective flow becomes too low to carry any inclusions larger than tolerant ones down to the bottom is defined as critial time. Then, the size of bottom cone of inclusions is equal to that of equiaxed crystal zone formed in the critial time. In this paper, the method for determining critial time was proposed, and the numerical simulation on the formation of bottom equiaxed crystal zone was carried out. A 27Cr2Mo1V steel ingot of 68 tons in weight was studied. From the results of numerical simulation, the weight ratio of cut tail end to ingot body was 8.11%. This result corresponds with the weight ratio of 8.8% in production practice of the same ingot approximately.
E-mail Alerts
