A method for preparing a full negative poisson's ratio energy-absorbing member

Abstract

The application belongs to the technical field of advanced manufacturing and mine machinery equipment, and discloses a preparation method of a full-negative Poisson ratio energy-absorbing component, which solves the problem that the existing energy-absorbing component design cannot meet the high energy-absorbing demand under extreme impact working conditions. The method comprises the following steps: (1) full-parameterization design of a macro-negative Poisson ratio structure based on multi-target Bayesian optimization; (2) preparation and process parameter simulation optimization of a micro-negative Poisson ratio steel forming powder; (3) laser additive-warm subtractive composite preparation of a full-negative Poisson ratio porous structure component; and (4) post-heat treatment of the full-negative Poisson ratio porous structure component and macroscopic and microscopic toughening regulation. The application greatly improves the energy-absorbing efficiency, breaks through the bottleneck of high-precision preparation of a complex interconnected porous structure, and realizes the optimal balance of full-parameterization design and multi-target performance.

Description

Technical Field

[0001] This invention belongs to the field of advanced manufacturing and mining machinery equipment technology, and particularly relates to a method for preparing a fully negative Poisson's ratio energy-absorbing component. Background Technology

[0002] In recent years, with the continuous increase in the depth and intensity of coal mining, rockburst disasters have become increasingly serious, posing a severe threat to safe coal mine production. As a key piece of equipment for resisting rockbursts, the performance of hydraulic supports for coal mine anti-rockburst directly affects the safety of coal mine production. Energy-absorbing components, as the core components of these supports, can effectively absorb the enormous energy released by rockbursts, and their performance directly determines the overall impact resistance of the support. Due to the harsh service environment, energy-absorbing components not only require extremely high load-bearing capacity but also need to maintain a constant load-bearing capacity and provide sufficient clearance stroke during deformation and energy absorption, and the deformation mode must be stable and controllable.

[0003] At present, the existing technical solutions for the design and fabrication of high energy-absorbing components are mainly concentrated in the following aspects: (1) In terms of macroscopic energy-absorbing structure design: In recent years, negative Poisson's ratio structures have shown significant advantages in energy absorption and impact resistance due to their unique deformation mechanism of lateral expansion under tension and lateral contraction under compression, and have become an important research direction for energy-absorbing components. Traditional energy-absorbing structures mostly adopt reentry honeycomb structures, foldable structures or rotationally symmetric structures. These structures can improve energy absorption efficiency to a certain extent, but their design methods still rely on experience, and parametric design is difficult, making it difficult to achieve system optimization and accurate prediction under different working conditions. In contrast, the three-period minimal surface (TPMS) structure, as a porous structure generated by mathematical models, has high specific surface area and high porosity, allowing for fully parametric design, and can uniformly absorb impact energy in multiple directions. However, the geometry of the minimal surface structure is extremely complex, posing a great challenge to the actual manufacturing process. (2) In terms of energy-absorbing material development: Traditional metal materials often cannot achieve both high strength and high elongation under strong impact conditions. In recent years, Academician He Manchao's team has developed microscopic negative Poisson's ratio steel. Through special composition control and multi-coherent interface design, the negative Poisson's ratio effect has been realized at the microscopic scale. When subjected to external impact, the material can control the energy absorption path through the unique crystal structure evolution, thus exhibiting excellent constant resistance large deformation characteristics and extremely high strength and toughness matching. However, how to process this high-performance microscopic negative Poisson's ratio steel material into a macroscopic three-period minimal curved surface structure to achieve the superposition of the "macroscopic + microscopic" dual energy absorption mechanism has not yet been found. (3) In terms of complex porous structure manufacturing process: For complex topological structures such as TPMS, traditional machining cannot be achieved. At present, laser additive manufacturing (such as SLM) is mostly used for layer-by-layer stacking. However, single additive manufacturing has problems such as large heat-affected zone, high residual stress, easy deformation and microcracks. Moreover, the porous structure surface is prone to step effect and high roughness, which seriously weakens the fatigue life and mechanical properties of the component. Therefore, "laser-based additive and subtractive composite manufacturing," which combines additive forming with subtractive finishing, has become the optimal solution. However, current composite machining typically employs cold subtraction, which results in extremely high cutting resistance when dealing with high-hardness alloys or materials that cool rapidly after additive manufacturing, leading to severe tool wear and machining deformation. The "heated subtraction technology" that has emerged in recent years utilizes the thermal softening effect of materials at high temperatures and the reduction in dislocation slip resistance, achieving a 30%-50% reduction in cutting force and significantly improving machining efficiency and part performance. However, there are currently no reports of a systematic fabrication method that integrates "heated subtraction technology" with the additive manufacturing of microscopic negative Poisson's ratio steel to prepare complex components with a fully negative Poisson's ratio.

[0004] In summary, existing energy-absorbing component designs are mostly limited to simple macroscopic structural optimization or material changes, and are constrained by the limitations of machining precision and efficiency of complex components, making it difficult to meet the high energy absorption requirements under extreme impact conditions. There is an urgent need to develop a novel method for fabricating energy-absorbing parts that can deeply integrate macroscopic minimal surface topology design, the intrinsic properties of microscopic negative Poisson's ratio materials, and a supporting efficient and precise composite manufacturing process. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a fully negative Poisson's ratio energy-absorbing component, which effectively solves the problem that the design of existing energy-absorbing components is mostly limited to a single macroscopic structural optimization or material change, and is constrained by the bottleneck of processing accuracy and efficiency of complex components, making it difficult to meet the high energy absorption requirements under extreme impact conditions.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing a fully negative Poisson's ratio energy-absorbing component, comprising the following steps: S1, full parameterization design of macroscopic negative Poisson's ratio structure based on multi-objective Bayesian optimization; S2, preparation of microscopic negative Poisson's ratio steel forming powder and simulation optimization of process parameters; S3, preparation of fully negative Poisson's ratio porous structure component by laser additive manufacturing-heated subtractive manufacturing composite; S4, post-heat treatment and macroscopic and microscopic strengthening and toughening control of the fully negative Poisson's ratio porous structure component.

[0007] Further, step S1 includes: S11, proposing a three-dimensional negative Poisson's ratio deformation design method based on the three-period minimal surface structural unit; S12, using a multi-objective Bayesian optimization algorithm, with the objective functions of maximizing energy absorption, minimizing peak stress, and lightweighting, defining the unit type, size, and porosity as variables for iterative optimization; S13, constructing a parametric model through implicit modeling, selecting the Pareto optimal solution set, and finally generating a three-dimensional digital model with both high volumetric surface area and negative Poisson's ratio effect, and deriving a three-dimensional slice model as a printing model for subsequent additive and subtractive composite manufacturing.

[0008] Further, step S2 includes: First, preparing microscopic negative Poisson's ratio steel powder through a powder spraying process as a raw material for laser additive manufacturing; then, establishing a thermo-mechanical coupled finite element model to study the influence of laser additive manufacturing process parameters on the molten pool morphology, cooling rate, and temperature field, and optimizing the process parameters using the response surface methodology to control the accumulation of residual stress during the forming process and ensure the microstructure inheritance characteristics of the microscopic negative Poisson's ratio steel under solidification; finally, establishing a quantitative response relationship among process parameters, microstructure, and mechanical properties, and outputting the optimal laser forming parameter package.

[0009] Furthermore, step S3 includes: S31, importing the three-dimensional slice model output in step S1 into a composite processing equipment equipped with a coaxial powder feeding system and a five-axis linkage milling module to develop a composite processing technology that adds and subtracts material simultaneously; S32, using the laser forming parameters optimized in step S2 to perform laser cladding deposition layer by layer; S33, before the additive layer has cooled to 20℃-25℃, controlling the material at 400℃-600℃, and directly performing five-axis precision milling.

[0010] Furthermore, in step S4, the process parameters for the post-heat treatment of the fully negative Poisson's ratio porous structure component are as follows: First, heat to 1000℃ and hold at 1000℃ for 45 min; then, cool to 300℃ at a cooling rate of 30℃ / s and hold at 300℃ for 20 min; finally, cool to 20℃-25℃ at a cooling rate of 1-5℃ / s.

[0011] Furthermore, in step S4, the post-heat treatment of the fully negative Poisson's ratio porous structure provides the driving force for the evolution of the microstructure, regulates the ratio of martensite to austenite inside the material, promotes the precipitation of nanoscale carbides, and inhibits the propagation of microcracks; through the synergistic energy dissipation mechanism of the gradual collapse of the macroscopic minimal surface structure and the microscopic phase transformation, the fully negative Poisson's ratio energy-absorbing component with optimal strength and toughness matching and high comprehensive dynamic energy absorption efficiency is finally obtained.

[0012] Furthermore, in step S4, the phase transformation law is quantitatively analyzed using XRD Rietveld full-spectrum refinement and EBSD phase diagram technology, and the volume fraction of thin-film residual austenite is adjusted to 10%-15%.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are: (1) The present invention achieves a great improvement in energy absorption efficiency through the synergistic effect of macro- and micro dual negative Poisson ratio mechanisms: For the first time, the macro-scale three-period minimal surface negative Poisson ratio topology is combined with the micro-scale negative Poisson ratio steel material. The efficient elastic-plastic deformation of the macro-scale porous core layer and the phase transformation strengthening and multiple coherent interfaces of the micro-material greatly enhance the energy dissipation capability under multi-axis complex loads.

[0014] (2) This invention breaks through the bottleneck of high-precision fabrication of complex interconnected porous structures: a laser additive-heated subtractive composite manufacturing process is developed and applied, utilizing the residual heat generated during the additive process for high-temperature cutting. The yield strength of the material decreases significantly at high temperatures, and the cutting force is greatly reduced, completely solving the problems of severe tool wear and low processing efficiency in cold machining of high-hardness alloys, and realizing the precision forming of porous components without step effect.

[0015] (3) The present invention achieves the optimal balance between full parameterization design and multi-objective performance: the multi-objective Bayesian optimization algorithm is used to iteratively optimize the size, porosity and other properties of the three-period minimal surface unit, completely eliminating the blindness of traditional energy-absorbing components that rely on experience design, and realizing the controllable and quantitative design of multiple objectives such as energy absorption, peak stress and structural lightweighting, thus ensuring the high reliability of the component under impact load. Attached Figure Description

[0016] Figure 1 This is a flowchart of the preparation method of the fully negative Poisson's ratio energy-absorbing component of the present invention.

[0017] Figure 2 This is a flowchart of the negative Poisson's ratio structure design method based on a three-period minimum surface in Example 1. Detailed Implementation

[0018] Example 1: This example provides a method for preparing a fully negative Poisson's ratio energy-absorbing component, such as... Figure 1 As shown, the process includes the following steps: S1, Full parameterization design of macroscopic negative Poisson ratio structure based on multi-objective Bayesian optimization.

[0019] S11. Based on the three-period minimal surface (Gyroid, Primitive, Diamond) structural unit, a three-dimensional negative Poisson's ratio structural design method is proposed.

[0020] S12. Using a multi-objective Bayesian optimization algorithm, with the objective functions of maximizing energy absorption, minimizing peak stress, and lightweighting (i.e., porosity of 60%-70%), the element type, size, and porosity are defined in the variable space for iterative optimization.

[0021] S13. A parametric model is constructed using implicit modeling methods, and the Pareto optimal solution set is selected. Finally, a three-dimensional digital model with both high volumetric surface area and negative Poisson's ratio effect is generated, and the three-dimensional slice data (model) is exported as a printing model for subsequent additive and subtractive composite manufacturing. Finally, its performance is verified through a combination of simulation and experimentation.

[0022] like Figure 2As shown, this embodiment focuses on the design of a negative Poisson's ratio structure using three-period minimal surfaces (TPMS), systematically studying the response relationship between geometric design and dynamic energy absorption mechanisms. First, based on a comparison of the geometric characteristics (specific surface area, curvature distribution, connectivity) of Gyroid (G), Primitive (P), and Diamond (D) type minimal surface elements, a parametric model is constructed using implicit modeling. Input variables include element size, porosity, and geometric deformation factor. A candidate structure library is generated with high volumetric surface area and negative Poisson's ratio as optimization objectives. Subsequently, a dynamic compression model is established using ANSYS to simulate and analyze the influence of parameters, studying the deformation modes, energy absorption, efficiency stability, and peak stress of various elements. Further, a multi-objective Bayesian optimization framework is constructed: with maximizing energy absorption, minimizing peak stress, and lightweighting as objective functions, element type (discrete variable), size, and porosity are defined as variable spaces. Iterative optimization is performed using a Gaussian process regression surrogate model and an expected improvement acquisition function to screen Pareto optimal solutions and verify manufacturability. The aforementioned minimal curved surface Poisson's ratio structure was fabricated using fused deposition modeling (FDM) plastic 3D printing technology. Quasi-static compression and cyclic loading experiments were used to quantify the structure's energy absorption efficiency, compressive strength, and other performance indicators, which were then compared with the numerical simulation results to verify the optimization results of the minimal curved surface negative Poisson's ratio structure. Finally, high-speed DIC technology was used to analyze the deformation mechanism under dynamic compression, and an energy absorption prediction model was established based on the principle of energy conservation. Building upon this, the performance was verified through SLM additive manufacturing and drop-weight tests, further optimizing the minimal curved surface negative Poisson's ratio structure. Ultimately, this achieved a controllable design of its structure and function, forming a closed-loop technical route of "design-simulation-optimization-verification".

[0023] S2. Preparation and process parameter optimization of microscopic negative Poisson's ratio steel forming powder.

[0024] First, microscopic negative Poisson's ratio steel powder is prepared by powder spraying process and used as raw material for laser additive manufacturing.

[0025] Subsequently, a thermo-mechanical coupled finite element model was established using software such as ANSYS to systematically study the influence of laser additive manufacturing process parameters such as laser power, scanning speed, layer thickness, and scanning path on the molten pool morphology, cooling rate, and temperature field.

[0026] This embodiment demonstrates that: ① The evolution of the molten pool morphology: Laser power and scanning speed jointly determine the bulk energy density. Too low an energy density leads to unfused porosity; too high an energy density causes the "keyhole effect" and elemental burn-off; as power increases or speed decreases, the aspect ratio of the molten pool increases significantly. ② Cooling rate and heat accumulation: The faster the scanning speed and the thinner the layer, the higher the local cooling rate (typically reaching 10³-10⁵ °C / s). Extremely high cooling rates are key to preserving the microscopic negative Poisson's ratio characteristics; however, as the number of deposition layers increases, the heat accumulation effect intensifies, the cooling rate of the upper layer decreases non-linearly, and the temperature gradient gradually flattens. ③ Residual stress and path optimization: Reciprocating unidirectional scanning leads to severe stress concentration and macroscopic warping; using "interlayer rotation (e.g., 67° or 90°)" or "chessboard partitioning" scanning paths can effectively reduce the directionality of heat flow conduction, making the temperature field distribution more uniform, thereby reducing the peak macroscopic residual stress of the formed part by 20%-40%.

[0027] By combining response surface methodology to optimize process parameters, residual stress accumulation during forming can be effectively controlled, and the microstructure genetic characteristics of micro-negative Poisson's ratio steel under rapid solidification can be guaranteed.

[0028] Finally, a quantitative response relationship between "process parameters - microstructure - mechanical properties" is established, and the optimal laser forming parameter package is output. In this embodiment, the optimal laser forming parameters are: laser power 1800W, scanning speed 1500mm / s, single layer thickness 0.3mm, and scanning rotation angle between adjacent layers 67°.

[0029] S3. Laser additive manufacturing-heated subtractive manufacturing composite fabrication of porous structural components with full negative Poisson ratio.

[0030] S31. Import the three-dimensional slice model output in step S1 into a composite machining equipment equipped with a coaxial powder feeding system and a five-axis linkage milling module to develop a composite machining process of "adding and subtracting at the same time".

[0031] S32. Laser cladding deposition is performed layer by layer using the laser forming parameters optimized in step S2.

[0032] S33. Before the additive layer cools down to room temperature (20℃-25℃) (i.e., using the residual heat of laser additive manufacturing or external adaptive laser heating), the material is precisely controlled to be in a specific high temperature range (400℃-600℃) and five-axis precision milling is performed directly.

[0033] Step S33 utilizes the high-temperature thermal softening effect of the material in heated subtractive processing to reduce the yield strength and dislocation slip resistance, thereby reducing the cutting force by 30%-50%.

[0034] The "addition and subtraction" composite machining process not only effectively removes the inherent step effect and roughness of the porous structure surface in additive manufacturing, achieving efficient and high-precision forming of complex interconnected pore structures with extremely small curved surfaces, but also significantly extends tool life and reduces residual stress caused by cold working. In this embodiment, the "addition and subtraction" composite machining process reduces the surface roughness of the inner wall of the porous structure from 15μm-40μm in the original additive state to below 1.6μm.

[0035] S4. Post-heat treatment and macro- and micro-strengthening control of porous structural components with full negative Poisson ratio. Macro- and micro-strengthening control means that the strength and toughness of the material are improved in a synergistic manner at the macro and micro levels.

[0036] A post-heat treatment process is applied to the integrally formed, fully negative Poisson's ratio porous structure component from step S3. By precisely controlling the heat treatment temperature, holding time, and cooling rate (e.g., using a staged quenching process), residual stress from the composite manufacturing process is effectively released.

[0037] In this embodiment, the process parameters for the post-heat treatment of the fully negative Poisson's ratio porous structure component are as follows: First, heat to 1000℃ and hold at 1000℃ for 45 min; then, cool to 300℃ at a cooling rate of 30℃ / s and hold at 300℃ for 20 min; finally, air cool (approximately 1-5℃ / s) to room temperature (20℃-25℃).

[0038] Meanwhile, heat treatment provides the impetus for the evolution of the microstructure, regulates the ratio of martensite to austenite within the material, promotes the precipitation of nanoscale carbides, and inhibits the propagation of microcracks. Through the synergistic energy dissipation mechanism of the gradual collapse of the macroscopic minimal surface structure and the microscopic phase transformation, a mine hydraulic support with optimal strength and toughness matching and extremely high comprehensive dynamic energy absorption efficiency with a full negative Poisson's ratio is finally obtained.

[0039] In this embodiment, the phase transformation law is quantitatively analyzed using XRD Rietveld full-spectrum refinement and EBSD (electron backscattering diffraction) phase diagram technology, with the aim of precisely controlling the volume fraction of thin-film retained austenite to 10%-15%. The dispersed coherent precipitation behavior of 5-20 nm alloy carbides is confirmed by high-resolution transmission electron microscopy (HR-TEM) and SAED (selected area electron diffraction).

[0040] In this embodiment, to elucidate the toughening mechanism, in-situ SEM (scanning electron microscope) dynamic fracture testing and fracture morphology analysis will be used to visually capture and confirm the "dislocation pinning / crack deflection" effect caused by nano-carbide and the "crack tip passivation" mechanism caused by the residual austenite TRIP (phase transformation induced plasticity) effect, thus confirming their strong inhibitory effect on microcrack propagation from a physical metallurgical perspective.

[0041] This invention is the first to combine a macroscopic three-period minimal curved surface negative Poisson's ratio topology with a microscopic negative Poisson's ratio steel material with a fully negative Poisson's ratio structure, achieving a synergistic improvement in impact energy absorption performance across macroscopic and microscopic scales. The efficient elastoplastic deformation of the macroscopic porous core layer, combined with the phase transformation strengthening and multiple coherent interfaces of the microscopic material, greatly enhances the energy dissipation capability under complex multiaxial loads.

[0042] This invention creatively introduces a "heated subtractive processing" strategy in the preparation of complex porous structures, overcoming the technical barriers of high internal stress and easy tool wear caused by the traditional additive and subtractive processing method of "cooling after additive processing and then subtracting". By using the residual heat generated in the additive process for high-temperature cutting, the yield strength of the material is significantly reduced at high temperature and the cutting force is greatly reduced, realizing the precision forming of porous components without step effect, and breaking through the bottleneck of high-precision preparation of complex interconnected porous structures.

[0043] This invention utilizes a multi-objective Bayesian optimization algorithm to iteratively optimize the size and porosity of three-period minimal surface units, completely eliminating the blindness of traditional energy-absorbing components that rely on empirical design. It achieves controllable and quantitative design of multiple objectives such as energy absorption, peak stress, and structural lightweighting, ensuring high reliability of the components under impact loads. It also constructs a closed-loop system for the preparation of high-performance energy-absorbing components, covering "multi-objective Bayesian parametric modeling → thermo-mechanical coupling process simulation → genetic control of residual stress from material addition and subtraction → post-processing microstructure regulation".

[0044] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing a fully negative Poisson's ratio energy-absorbing component, characterized in that, Includes the following steps: S1. Fully parameterized design of macroscopic negative Poisson ratio structures based on multi-objective Bayesian optimization; S2. Preparation and process parameter optimization of microscopic negative Poisson's ratio steel forming powder; S3. Laser additive manufacturing-heated subtractive manufacturing composite fabrication of porous structural components with full negative Poisson ratio; S4. Post-heat treatment and macroscopic and microscopic strengthening and toughening control of porous structural components with full negative Poisson ratio.

2. The method for preparing a fully negative Poisson's ratio energy-absorbing component according to claim 1, characterized in that, Step S1 includes: S11. Based on the three-period minimal surface structural unit, a three-dimensional negative Poisson's ratio deformation design method is proposed. S12. Using a multi-objective Bayesian optimization algorithm, with the objective functions of maximizing energy absorption, minimizing peak stress, and lightweighting, the element type, size, and porosity are defined in the variable space for iterative optimization. S13. Construct a parametric model using implicit modeling methods, select the Pareto optimal solution set, and finally generate a three-dimensional digital model with both high volumetric surface area and negative Poisson's ratio effect. Export the three-dimensional slice model as the printing model for subsequent additive and subtractive composite manufacturing.

3. The method for preparing a fully negative Poisson's ratio energy-absorbing component according to claim 2, characterized in that, Step S2 includes: First, microscopic negative Poisson's ratio steel powder is prepared by powder spraying process and used as raw material for laser additive manufacturing; Subsequently, a thermo-mechanical coupled finite element model was established to study the influence of laser additive manufacturing process parameters on the molten pool morphology, cooling rate and temperature field. The process parameters were optimized by combining response surface methodology to control the accumulation of residual stress during the forming process and to ensure the microstructure inheritance characteristics of micro-negative Poisson's ratio steel under solidification. Finally, a quantitative response relationship among process parameters, microstructure, and mechanical properties is established, and the optimal laser forming parameter package is output.

4. The method for preparing a fully negative Poisson's ratio energy-absorbing component according to claim 3, characterized in that, Step S3 includes: S31. Import the three-dimensional slice model output in step S1 into a composite machining equipment equipped with a coaxial powder feeding system and a five-axis linkage milling module to develop a composite machining process that increases and decreases simultaneously. S32. Laser cladding deposition is performed layer by layer using the laser forming parameters optimized in step S2; S33. Before the additive layer has cooled to 20℃-25℃, control the material at 400℃-600℃ and directly perform five-axis precision milling.

5. The method for preparing a fully negative Poisson's ratio energy-absorbing component according to claim 1, characterized in that, In step S4, the process parameters for the post-heat treatment of the porous structure component with a full negative Poisson's ratio are: First, heat to 1000℃ and hold at 1000℃ for 45 minutes; then, cool to 300℃ at a cooling rate of 30℃ / s and hold at 300℃ for 20 minutes; finally, cool to 20℃-25℃ at a cooling rate of 1-5℃ / s.

6. The method for preparing a fully negative Poisson's ratio energy-absorbing component according to claim 5, characterized in that, In step S4, the post-heat treatment of the fully negative Poisson's ratio porous structure provides impetus for the evolution of the microstructure, regulates the ratio of martensite to austenite inside the material, promotes the precipitation of nanoscale carbides, and inhibits the propagation of microcracks. By utilizing the synergistic energy dissipation mechanism of the gradual collapse of macroscopic minimal surface structures and microscopic phase transitions, a fully negative Poisson's ratio energy-absorbing component with optimal strength and toughness matching and high comprehensive dynamic energy absorption efficiency was finally obtained.

7. The method for preparing a fully negative Poisson's ratio energy-absorbing component according to claim 6, characterized in that, In step S4, the phase transformation law is quantitatively analyzed using XRD Rietveld full-spectrum refinement and EBSD phase diagram technology, and the volume fraction of thin film residual austenite is adjusted to 10%-15%.

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