Simulation Analysis of Stress Field of Walnut Shell Composite Powder in Laser Additive Manufacturing Forming

A calculation model of stress field in laser additive manufacturing of walnut shell composite powder(walnut shell/Co-PES powder)was established.The DFLUX subroutine was used to implement the moveable application of a double ellipsoid heat source by considering the mechanical properties varying with temperature.The stress field was simulated by the sequential coupling method,and the experimental results were in good accordance with the simulation results.In addition,the distribution and variation of stress and strain field were obtained in the process of laser additive manufacturing of walnut shell composite powder.The displacement of laser additive manufacturing walnut shell composite parts gradually decreased with increasing preheating temperature,decreasing laser power and increasing scanning speed.During the cooling process,the displacement of laser additive manufacturing of walnut shell composite parts gradually increased with the increasing preheating temperature,decreasing scanning speed and increasing laser power.

Prediction and Analysis of Post-Treatment of Sustainable Walnut Shell/Co-PES Parts by Laser Sintering

In order to enhance the strength of sustainable walnut shell/Co-PES(WSPC)sintered parts,wax-filtrated posttreatment was carried out.The effects of treating fluid temperature,preheating time and immersion time on the bending strength of WSPC wax-filtrated parts were analyzed by single factor analysis method.To obtain an accurate model for predicting the bending strength of the WSPC wax-filtrated part,the experiments were involved by using Box-Behnken design(BBD).Main parameters,such as treating fluid temperature,preheating time and immersion time,and their interactive effects were analyzed through analysis of variance(ANOVA)and graphical contours.The results demonstrated that all parameters’direct effects were significant to bending strength of the WSPC wax-filtrated part.Its optimum value was 5.0 MPa when the treating fluid temperature of 70°C,preheating time of 50 min,and immersion time of 20 s.The predicted models effectively validated had good predicting accuracy.The WSPC wax-filtrated part using optimal processing parameters was processed by investment casting,and then the metal casting of dimensional stability and smooth surface was obtained.Investment casting was done using WSPC wax-filtrated parts under optimal process parameters and then metal parts with stable structure size and smooth surface can be obtained,which indicates that WSPC material can be used for investment casting.

Research on a Composite Biomass Insulation Material with Geopolymers as Binders and Forestry Waste as Fillers

A composite biomass insulation material,which uses geopolymers as adhesives and forestry waste as fillers,was proposed and experimentally tested.The orthogonal experimental method was adopted to analyze the optimum theoretical oxide molar ratios and the mass ratio of mixing water to binder(m_(w2)/m__(B))for preparing geopolymers.The influences of curing regimes(including one-stage and two-stage curing methods)and m_(w2)/m_(B) ratios of the insulation materials on mechanical,thermal,and hydraulic performances were also studied by experiment.The results indicated that the optimum combination scheme of preparing geopolymers was molar ratio x_(SiO_(2))/x_(Na_(2)O)=3.3,x_(SiO_(2))/x_(Al_(2)O_(3))=3.2 and m_(w2)/m_(B)=0.5 with the highest mechanical strength of 34.21 MPa.Besides,the best curing conditions of the composite material were the curing temperatures of 85°C and 70°C under the two-stage curing regime,which could achieve the low heat conductivity of 0.123 and 0.125 W/(m·K),and the high mechanical strength of 1.70 MPa and 1.71 MPa,respectively.The optimum m_(w2)/m_(B)ratios of the biomass material were 0.5 to 0.55 with heat conductivity of 0.114 to 0.125 W/(m·K).This novel composite insulation material has satisfying physical performances,which is helpful for achieving building energy conservation.