| Using the natural characteristics of artificial fast-growing forest wood,such as high strength,thermal insulation,recyclability,etc.,research on the use of new technology in wood bionic winding processing,and develop high-strength pressure conveying pipes with excellent thermal insulation,anti-seismic and anti-corrosion properties,which are water conservancy projects and urban underground.Pipe network construction provides a new type of pressure-transport pipeline that is environmentally friendly.Two types of composite strips were designed according to the winding characteristics.The mechanical properties of failure modes,Poisson's ratio,elastic modulus and tensile strength of the composite strips were studied.Two composite sheets were studied according to the transformation formula and the Hankinsion formula.The off-axial tensile elastic modulus and Poisson's ratio were used to study the off-axis tensile strength of the two composite sheets based on the Hankinsion formula,the maximum stress strength criterion and the Tsai-Hill strength criterion.The mechanical properties of the pipe structural layer were studied by preparing the plywood according to the winding mode and the winding angle of the structural layer veneer strip.The flat plate was prepared according to the winding method of the inner liner layer and the outer protective layer,and the sandwich plywood with the structural layer plywood was used to study the mechanical properties.The mechanical properties of the structural layer laminate and the sandwich laminate were simulated based on ANSYS finite element software.Detecting the ring stiffness,failure water pressure,corrosion resistance,density,hoop tensile strength and axial tensile strength of the pipe,based on ANSYS finite element software to simulate the ring stiffness test and water pressure resistance test of the pipe,to composite strip The thickness and elastic parameters,the winding angle,the thickness of the inner liner and the elastic parameters,the thickness of the outer protective layer and the elastic parameters are the main input variables,and the simulation results are compared with the experimental values to analyze the error.The research results are as follows:(1)Based on the characteristics of the winding unit,winding method and structural layer of the wood-based winding pipe,the stiffness prediction formula of the structure,the lining layer and the outer protective layer of the wood-based winding pipe is established,and the stiffness of the overall structure of the pipe is established according to the principle of stiffness superposition.Predict the formula and edit the calculation program.(2)Analysis of orthogonal composite strips.The predicted value of the Hankinsion formula has a large error with the experimental value of the off-axis tensile elastic modulus of the unfiber-bonded composite strip.The transformation formula can accurately predict the elastic modulus of the composite strip of the wood-based wound tube under the off-axis tension.The change rule of quantity;after the addition of fiber cloth,the change of elastic modulus with the off-axis angle is more complicated,which makes it difficult to accurately predict the change of elastic modulus of the transformation formula;the quadratic function by numerical fitting can beaccurate.Predict the actual variation trend of Poisson's ratio and the Poisson's ratio value of the orthogonal composite plate;The Tsai-Hill strength criterion can accurately predict the variation of tensile strength of orthogonal composite strips.The addition of fiber cloth,the maximum stress intensity criterion and the predicted value of Tsai-Hill strength criterion are lower than the experimental value and the error is large.Therefore,the change in tensile strength cannot be accurately predicted.(3)Analysis of the skewed composite strips The prediction results of the Hankinsion formula can more accurately predict the axial test values of the skew composite strips;the prediction value of the transformation formula can more accurately predict the hoop elastic modulus of the skew composite strip.The fitted quadratic function can accurately predict the actual variation trend and Poisson's ratio of the oblique Poisson's ratio of the skewed composite strip,and the cubic function of the fitting can accurately predict the skewed composite strip with the Poisson Compared with the actual variation trend and Poisson's ratio values,the Hankinsion formula and the Tsai-Hill strength criterion can accurately predict the axial tensile strength of the skew composite panel,and the Tsai-Hill strength criterion can more accurately predict the ring of the oblique composite strip.The tensile strength.(4)The axial elastic modulus and the circumferential elastic modulus of the orthogonal plywood gradually increase with the increase of the winding angle,and the circumferential elastic modulus is smaller than the axial elastic modulus at different winding angles;The axial elastic modulus of the skewed plywood is always greater than the hoop elastic modulus.The axial elastic modulus of the oblique plywood decreases with the increase of the off-axis angle,and the hoop elastic modulus increases with the increase of the off-axis angle.Big.At different winding angles,the axial elastic modulus of the skewed plywood is greater than the axial elastic modulus of the orthogonal plywood,and the hoop elastic modulus of the oblique plywood is greater than the hoop elastic modulus of the orthogonal plywood,with As the winding angle increases,the difference in the elastic modulus of the two plywoods gradually decreases.The circumferential elastic modulus of the orthogonal sandwich panel and the oblique sandwich panel gradually increases with the increase of the winding angle,and the variation of the sandwich laminate with the winding angle is not very significant.The ANSYS finite element software was used to simulate the elastic modulus of orthogonal plywood and orthogonal sandwich laminate.The correlation between the ANSYS simulation value of the hoop elastic modulus and the experimental value was better than the theoretical value,and the test value was higher than the simulation.Value,the analog value is higher than the theoretical value.(5)The mean value of the ring stiffness of the wood-based wound pipe is 4461 N/m2,and the average error is 7.5%.The calculated value and the experimental value are within the range of the test value.Compared with the average value of the test value,the calculated value has an error of 0.9%,and the error of the simulated value is 9.6%.From the experimental data,both methods can better predict the ring stiffness of wood-based pipes with small errors.When subjected to radial load,the upper end of the pipe moves downward and the two sides are outwardly deformed.When the radial deformation is 0.009 mm,the circumferential deformationis 0.003376 mm,the axial direction is not deformed;the circumferential deformation is in the wood-based pipe.The deformation of both sides of the middle part is the largest,and gradually decreases along the pipe wall toward the bottom end and the top end;when the pipe is pressed,the top and bottom outer surfaces are subjected to compressive stress,the inner surface is subjected to tensile stress,and the outer surfaces are subjected to tensile stress on both sides.The inner surface is subjected to compressive stress.The axial stress is much smaller than the circumferential and radial stresses;the circumferential and axial shear stresses are obtained on the inner surfaces of both sides of the pipe,and the minimum value is distributed in the strip on the inner and outer surfaces of the pipe.The maximum and minimum values of the circumferential and radial and axial and radial shear stresses are taken at the edges of the front and rear ends of the pipe.The tensile strength,tensile modulus and flexural strength,and flexural modulus of the sample are gradually decreased in the medium.The two corrosive media are first corroded at the surface of the sample to form a hole,and then the medium is further extended to the substrate.Diffusion,forming larger,deeper holes.When the retention of tensile strength,tensile modulus and flexural strength,and flexural modulus is 50% in a 30% sulfuric acid solution,the corresponding lifetimes are 357 d,1512 d,and 481 d and 817 d,respectively.When the retention of tensile strength,tensile modulus and flexural strength,and flexural modulus is50% in a 10% sodium hydroxide solution,the corresponding lifetimes are 368 d,1479 d,and 816 d and 480 d,respectively.Therefore wood base coil pipes are not suitable for conveying acid alkali medium,when conveying the need when this kind of material of lining layer design,selection of acid alkali resistant resin and reinforcing fiber?... |
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