A Contact Surface Design Method for the Pressure Distribution of the Target Object

Abstract

The present invention discloses a contact surface design method for a target body pressure distribution, belonging to the field of industrial design technology. The method comprises establishing a human biomechanical finite element model; applying a target body pressure distribution to the body surface; extracting the deformed body surface; determining the mechanical properties of the contact surface material; adding a deformation compensation amount, and fitting the surface. The contact surface design method of the present invention can directly achieve the target body pressure distribution for the target population through the designed surface, provided that the contact material is known. This avoids the blindness of contact surface design requiring a target contact body pressure distribution and minimizes the number of design iterations during the design process of such contact surfaces, thereby achieving a convenient and efficient design process and saving design development time and costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial design, and in particular relates to a contact surface design method oriented to target body pressure distribution. Background Art

[0002] Human-machine contact surfaces are a crucial component of human-machine interaction. They transmit force through contact pressure to achieve various functions, such as support, cushioning, manipulation, and recognition. Objective properties of contact pressure, such as size, distribution, and gradient, directly affect the human body, influencing subjective experiences such as comfort.

[0003] The direct effect of pressure on the human body is the transmission of force to the body's surface and internal tissues, including subcutaneous tissue, blood vessels, nerves, as well as muscles, tendons, ligaments, etc., generating contact force on the body surface and causing tissue stress internally. When the pressure distribution acting on the human body is unreasonable, excessive pressure and shear force will hinder the oxygen supply to human tissues. Long-term adverse effects will lead to long-term hypoxia of human tissues and thus pressure injuries. Typical examples are pressure sores in patients who use wheelchairs for a long time or who are bedridden for a long time. These are the result of long-term excessive local pressure on the body surface affecting blood circulation in that area, leading to tissue ulcers and necrosis. If the undesirable contact pressure can be reduced to a certain safe level, the occurrence of pressure injuries can be greatly reduced.

[0004] Contact pressure transmitted to the body's surface and internal tissues is sensed by nerves, forming a subjective perception in the brain. The impact of pressure on subjective perception is primarily reflected in comfort, particularly between the person and the chair. Among commonly used objective assessment methods for sitting comfort (including posture analysis, body pressure measurement, and electromyography), body pressure has the most significant correlation with subjective scores. Among body pressure parameters, mean pressure, peak pressure, and pressure distribution all influence subjective comfort, with body pressure distribution showing the most significant correlation with subjective ratings. The impact of body pressure distribution on comfort is not only evident in large-area contacts like the human-chair interface, but also in smaller-area contacts, such as the hand and the joystick, where contact pressure is even more relevant to subjective comfort than joint angle. The impact of pressure is particularly pronounced in specific areas, such as the fingertips, the distal palm near the index finger, and the proximal palm near the radius. Hand discomfort caused by poor contact pressure can further lead to upper limb fatigue and reduced grip strength, ultimately impacting operating ergonomics. Furthermore, the impact of contact pressure on subjective perception is also reflected in the tactile sensation that influences product style and emotional experience. To summarize, excessive contact pressure can cause discomfort or even pressure damage, while insufficient pressure can lead to insufficient support, which can also cause discomfort or even functional failure. Contact pressure has a great impact on the realization of product functions and the user experience, so a reasonable amount of pressure and its distribution are crucial.

[0005] Contact pressure is directly affected by load and contact area. Therefore, under a given load, the properties of the contact surface play a key role in the generation of pressure. Some contact surfaces are rigid, designed with a specific contact profile to match the human body, resulting in minimal deformation under load. A typical example is a joystick. Many other contact surfaces are flexible, utilizing materials and structures such as foam or air cells to deform under load. Examples include the surfaces of most seats, wheelchair seats, and mattresses. Flexible surfaces deform with load, adapting to the body through rebound and changing the contact area, thereby redistributing and alleviating body pressure. Therefore, the inherent properties of the flexible material or structure, such as the rigidity, thickness, and viscoelasticity of the foam, must be considered. Taking these factors into account, a well-designed contact profile that takes material properties into account can theoretically achieve the ideal contact area and, consequently, the target body pressure value and distribution.

[0006] To achieve a superior contact experience and optimal body pressure distribution, a variety of products are available. Actively controlled pressure-reducing cushions are a typical example. These cushions contain numerous small air control units. Sensors sense the body pressure distribution on the cushion and compare it with the target pressure in real time. Feedback from these units controls the air volume in the air control units, altering the contact area and bringing the actual body pressure closer to the target pressure. While effective, this approach requires additional equipment and energy input, resulting in high costs. This makes it difficult to implement in applications with limited space, requiring long-distance travel, or for simple, low-cost products. However, these products encompass the majority of the human-machine interface. Numerous design approaches exist for these products. For example, the material, structure, profile, size, and inclination of various seats can alter body pressure distribution, thus impacting comfort. Similarly, the thickness, size, inclination, and slot design of bicycle saddles can effectively control body pressure distribution, improve riding stability, and mitigate health risks associated with body pressure during cycling. In addition, numerous related testing and evaluation methods exist for verifying body pressure and comfort in existing products. For example, body pressure can be measured in zones. By comparing the peak, mean, gradient, and distribution of each zone's pressure with the ideal pressure, the design's rationality can be evaluated. Furthermore, numerous design guidelines have been developed, such as the recommended pressure range and distribution on the seat-body interface and the recommended shape of joystick handles. These guidelines are used to guide contact profile design, aiming to improve pressure values and distribution, as well as the user's subjective comfort.

[0007] Existing design methods provide correlations between specific product features and body pressure and comfort, or analyze certain qualitative influence trends, but none offer direct guidance on design dimensions. On the one hand, these methods are only applicable to existing, well-researched products and can only be designed based on product features with clearly defined influence patterns, such as the seat angle and back support of a car seat, the thickness of a wheelchair seat, or the width and thickness of a bicycle saddle. On the other hand, these design methods typically involve an initial qualitative analysis of the general contours of the contact surface, followed by prototype production. These prototypes are then tested using body pressure distribution testing. Based on the test results, modifications are attempted, followed by further trial production and testing, and this process is repeated until the target body pressure distribution requirements are met. Such methods are difficult to provide design guidance for the contact contours of emerging products, tools, or joysticks. They also struggle to ensure that the resulting design meets the pressure distribution requirements. Furthermore, they are highly unpredictable and require multiple rounds of design iteration and optimization, requiring significant development time and cost. Summary of the Invention

[0008] In response to the above-mentioned defects in the prior art, the present invention provides a contact surface design method for target body pressure distribution. The method can directly achieve the target body pressure distribution for the target population by designing a surface based on the known contact material, thereby avoiding the blindness of contact surface design with target contact body pressure distribution requirements and minimizing the number of design iterations in the design process of such contact surfaces. This achieves the purpose of facilitating and saving design and development time and costs, while also meeting the requirements of target body pressure distribution. In addition, the method can be widely applied to contact surfaces of various products and forms. It starts from the physical relationship between body pressure distribution and contact profile, rather than being limited to specific product features or contact surface properties, making the design method more universal.

[0009] The present invention is achieved through the following technical solutions:

[0010] A contact surface design method for target body pressure distribution includes the following steps:

[0011] Step 1: Establish a human biomechanical finite element model;

[0012] Step 2: Apply target body pressure distribution on the body surface;

[0013] Step 3: Extract the deformed body surface;

[0014] Step 4: Determine the mechanical properties of the contact surface material;

[0015] Step 5: Determine the minimum thickness after deformation and the amount of deformation compensation;

[0016] Step 6: Add deformation compensation and fit the surface.

[0017] Furthermore, the establishment of the human body biomechanical finite element model in step 1 specifically includes the following contents:

[0018] According to the contact contour to be designed, a human biomechanical finite element model of the target population is established. The contact contour includes bones, muscles, fat, soft tissue or skin. The human biomechanical finite element model is the entire human body or the part of the human body that is in contact with the contact contour.

[0019] Furthermore, the target body pressure distribution applied to the body surface in step 2 specifically includes the following:

[0020] Determine the target body pressure distribution pattern according to design requirements, apply the target body pressure distribution to the human body surface of the human biomechanical finite element model established in step 1 in the form of an isobaric curve, and divide the human body surface into areas with different target body pressure intervals.

[0021] Furthermore, the target body pressure distribution pattern should be determined so that the integral of the body pressure on the contact contour is equal to the external load that generates the contact body pressure.

[0022] Furthermore, the step 3 of extracting the deformed body surface specifically includes the following:

[0023] The human biomechanical finite element model with the target body pressure distribution applied in step 2 is submitted to a simulation calculation, and after the calculation is completed, the deformed body surface at the designed contact area is extracted;

[0024] If the contact surface is rigid, the extracted deformed surface is the designed rigid contact surface; if the contact surface is flexible, the isobaric curve on the deformed surface is retained and step four is continued.

[0025] Furthermore, the determination of the mechanical properties of the contact surface material described in step 4 specifically includes the following:

[0026] The mechanical properties of the contact surface material include compressive stress-strain relationship, shear stress-strain relationship, elastic hysteresis, viscosity or viscoelasticity, and based on the above mechanical properties of the contact surface material, a mathematical model between material pressure, thickness and deformation is determined.

[0027] Furthermore, the compressive stress-strain relationship is obtained by the following method:

[0028] If the contact surface material has been determined, it can be obtained through uniaxial compression test;

[0029] If the contact surface material is not determined, simulation is performed using a parameterized material constitutive model, and the appropriate material is selected based on the set parameters.

[0030] Furthermore, the determination of the minimum thickness after deformation and the deformation compensation amount described in step 5 specifically includes the following:

[0031] The design surface sampling points are extracted from the isobaric pressure curve on the deformed body surface retained in step 3, and the sampling distance is less than the allowable size of the design accuracy; and the following thickness variables are obtained based on the coordinates of the extracted design surface sampling points: the minimum thickness after deformation T min and the deformation reference thickness T0; the minimum thickness after deformation T min The deformation reference thickness T0 is selected based on the design goal or design experience, and is the distance between the deformed surface and the minimum thickness reference after deformation; the minimum thickness reference after deformation is the plane where the lowest sampling point after deformation is located;

[0032] The deformation compensation ΔT generated by the contact surface material after being subjected to body pressure can be obtained by the following formula:

[0033] T=T min +T0+ΔT

[0034] Where T is the thickness before deformation.

[0035] Furthermore, the addition of deformation compensation and surface fitting described in step 6 specifically includes the following:

[0036] The sampling point is translated in the direction of increasing thickness of the contact surface by the deformation compensation amount ΔT to obtain the fitting point. All the fitting points are used to fit a smooth surface with a continuity of not less than G1 order. The obtained deformation compensation amount ΔT is then added to the deformed surface, and the fitted surface is the designed flexible contact surface.

[0037] Compared with the prior art, the advantages of the present invention are as follows:

[0038] The contact surface designed by the contact surface design method for target body pressure distribution of the present invention is theoretically the same as the target body pressure distribution if the total load of the corresponding parts applied by the target population on the contour is equal to the total load of the target body pressure. This method is applicable to both rigid and flexible contact surfaces and to different product types and different shape contours. For rigid contact surfaces, the deformed surface contour under the target body pressure distribution is the design surface. For flexible contact surfaces, the body pressure distribution, the original size of the contact surface, and the amount of contact deformation can meet the stress-strain characteristics of the material in the contact area. Under the premise of meeting the target body pressure distribution requirements, various contact surfaces of different materials and properties for various products can be designed quickly and conveniently, effectively avoiding design blindness. In addition, there is no need for multiple rounds of inspection and modification during the design process. The surface designed using this method can basically directly achieve the target body pressure distribution for the target population, avoiding multiple rounds of design verification and iteration, and significantly reducing design time and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0040] Figure 1 Schematic diagram of a flow chart of a contact surface design method for target body pressure distribution according to the present invention;

[0041] Figure 2 is a schematic diagram of thickness variables;

[0042] Figure 3 This is a schematic diagram of the target body pressure distribution on the buttocks of a seat cushion;

[0043] Figure 4 The extracted body surface after being deformed by the target body facing the buttocks of a certain cushion;

[0044] Figure 5 It is the isobaric curve on the body surface after the target body pressure deformation of the buttocks of a certain cushion;

[0045] Figure 6 It is a mathematical model between pressure, thickness and deformation of a cushion material;

[0046] Figure 7 is the fitted contact surface facing the target body pressure of the buttocks of a seat cushion;

[0047] In the figure: fitting point 1, sampling point 2, minimum thickness reference after deformation 3, material bottom 4. DETAILED DESCRIPTION

[0048] In order to clearly and completely describe the technical solution and specific working process of the present invention, the specific implementation methods of the present invention are as follows in conjunction with the accompanying drawings:

[0049] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0050] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0051] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0052] Example 1

[0053] The following equilibrium relationship exists for contact conditions: when two objects are in contact, the interaction pressures acting on them are equal, and the deformed surfaces of the two contact areas coincide. Furthermore, when environmental conditions such as temperature and air pressure remain constant, the deformation of most materials is determined by the load magnitude and material properties. Based on these conditions, for two objects of known material, if the forces acting on them are known, their deformations can be determined. Similarly, under general contact conditions, the contact deformation of two objects in contact is related to the contact pressure between the two objects and their materials. Therefore, we can assume that the target pressure distribution is the actual contact pressure applied to the target body. The resulting deformed surface of the body coincides with the deformed contact contour due to contact equilibrium, and the pressure on the contact contour also corresponds to the target pressure distribution. Since both the deformed contact contour and the pressure distribution are known, the deformation can be determined based on the material properties and inferred from the contact surface before the force deformation, thus designing the contact contour. For rigid contact surfaces, the deformation is minimal or even negligible, but the aforementioned equilibrium relationship and design method still apply.

[0054] Therefore, a human biomechanical model is first established based on the biomechanical properties of human tissue. A target body pressure distribution is constructed based on design expectations, and the deformed body surface contour is obtained through simulation calculation and surface fitting. The mechanical properties of the contact material are analyzed, and a mathematical model is established between material pressure, thickness, and deformation. The deformation of the contact material is calculated based on the target pressure and expected thickness, and after compensating it to the deformed body surface position, a reconstructed contour is obtained and fitted to the actual desired design surface. If the contact contour is a rigid surface, there is no need to compensate for material deformation, and the deformed body surface contour under the target body pressure distribution is the design surface.

[0055] like Figure 1 FIG. 1 is a flow chart of a contact surface design method for target body pressure distribution according to an embodiment of the present invention. The contact surface design method specifically includes the following steps:

[0056] Step 1: Establish a human biomechanical finite element model, as follows:

[0057] Based on the contact profile to be designed, a human biomechanical finite element model of the target population is established, which may include but is not limited to bones, muscles, fat, soft tissue, skin, etc. The model can be the entire human body or a simplified part of the human body that is in contact with the contact profile. However, it needs to be able to apply a complete load that generates contact body pressure and be able to represent the contact working conditions of the entire human body.

[0058] Step 2: Apply target body pressure distribution on the body surface, as follows:

[0059] Determine the target body pressure distribution pattern based on design requirements and apply it to the surface of the human biomechanical finite element model established in step 1 using an isobaric body pressure curve. This divides the surface into regions where different target body pressure intervals are applied. It is important to note that the target body pressure distribution pattern in this step cannot be arbitrarily determined based on design requirements. It must also ensure that the integral of the body pressure over the contact contour is equal to the external load that generates the contact body pressure; otherwise, the force balance condition will not be met.

[0060] Step 3: Extract the deformed body surface, as follows:

[0061] Submit the human biomechanical finite element model, with the target pressure distribution applied in step 2, for simulation. After the calculation is complete, extract the deformed surface at the designed contact area. If the contact surface is rigid, such as a hard armrest, seat, or joystick, the extracted deformed surface represents the designed rigid contact surface. If the contact surface is flexible, retain the isobaric curve on the deformed surface and proceed to step 4.

[0062] Step 4: Determine the mechanical properties of the contact surface material, as follows:

[0063] Determine the mechanical properties of the contact surface material. The material mechanical properties here refer to the material properties related to the contact force and contact deformation, including but not limited to the compressive stress-strain relationship, shear stress-strain relationship, elastic hysteresis, viscosity, viscoelasticity, etc. The above-mentioned material mechanical properties require at least the compressive stress-strain relationship, and other material mechanical properties can be selected according to design needs. If the contact surface material has been determined, its compressive stress-strain relationship is recommended to be obtained through a uniaxial compression test; if the contact surface material has not been determined, its compressive stress-strain relationship can be simulated through a parameterized material constitutive model, and a suitable material can be selected according to the set parameters. Finally, based on the material properties related to the above-mentioned contact force and contact deformation, the mathematical model between the material pressure, thickness and deformation can be determined.

[0064] Step 5: Determine the minimum thickness after deformation and the amount of deformation compensation, as follows:

[0065] The design surface sampling points are extracted from the isobaric pressure curve on the deformed body surface retained in step 3, and the sampling distance is less than the allowable size of the design accuracy; and the following thickness variables are obtained based on the coordinates of the extracted design surface sampling points: the minimum thickness after deformation T min, selected according to design goals or design experience, it is recommended that the cushion design should be no less than 10mm, and the handle design should be no less than 5mm to prevent the buffer from bottoming out; the deformation reference thickness T0 is the distance between the deformed surface and the minimum thickness reference after deformation (the plane where the lowest sampling point after deformation is located); the deformation compensation amount ΔT is the deformation amount of the contact surface material after being subjected to body pressure. Obviously, the thickness T before deformation is related to the above thickness variables as shown in the attached figure. Figure 2 As shown, there are the following relationships:

[0066] T=T min +T0+ΔT

[0067] The value of ΔT is obtained by substituting T and the target body pressure value into the material mechanical properties obtained in step 4.

[0068] Step 6: Add deformation compensation and fit the surface, as follows:

[0069] The sampling point is translated in the direction of increasing thickness of the contact surface by the deformation compensation amount ΔT to obtain the fitting point. All the fitting points are used to fit a smooth surface with a continuity of not less than G1 order. The obtained deformation compensation amount ΔT is then added to the deformed surface, and the fitted surface is the designed flexible contact surface.

[0070] Example 2

[0071] Design a flexible seat cushion contact surface for a certain wheelchair with body pressure distribution requirements.

[0072] Step 1: Establish a human biomechanical finite element model, as follows:

[0073] The contact contour between the buttocks and the seat cushion needed to be designed, so a biomechanical finite element model of the 50th percentile human body of the target population was established, including bones, soft tissues, and skin. This model was then simplified to include only the buttocks and thighs.

[0074] Step 2: Apply target body pressure distribution on the body surface, as follows:

[0075] Apply the target body pressure distribution required by the design to the human body surface of the human biomechanical finite element model established in step 1 in the form of an isobaric curve. Figure 3 The areas shown here are subject to different target pressure intervals. A peak target pressure of 9 kPa is applied to the areas below the two ischial tuberosities. The target pressures in other areas decrease gradually from the peak pressure zone outward, with a 1 kPa difference between target pressures in adjacent areas. Verification shows that the integral of the pressure over the contact contour is equal to the gravity load that generates the contact pressure.

[0076] Step 3: Extract the deformed body surface, as follows:

[0077] The human biomechanical finite element model with the target body pressure distribution applied in step 2 is submitted to the simulation calculation. After the calculation is completed, the deformed body surface of the designed contact area, i.e., the buttocks and thighs, is extracted. The extracted body surface is shown in the attached figure. Figure 4 The designed contact surface is flexible and needs to retain the isobaric curve on the body surface after deformation, as shown in the attached figure. Figure 5 shown.

[0078] Step 4: Determine the mechanical properties of the contact surface material, as follows:

[0079] Determine the mechanical properties of the contact surface material. According to the design requirements, only the compressive stress-strain relationship is considered. During the design, the contact surface material has not been determined and experimental data cannot be obtained. Its compressive stress-strain relationship is simulated using a parameterized second-order Ogden material constitutive model. The material parameters are selected as μ1 = 0.08 MPa, α1 = 20, and μ2 = 3×10 -5 MPa, α2=10, the mathematical model between material pressure, thickness and deformation is determined by the constitutive model, as shown in the attached Figure 6 shown.

[0080] Step 5: Determine the minimum thickness after deformation and the amount of deformation compensation, as follows:

[0081] Extract the design surface sampling points on the isobaric curve on the deformed body surface retained in step 3, with a sampling distance of 10 mm; and obtain the following thickness variables based on the coordinates of the extracted design surface sampling points: the minimum thickness after deformation T min This design belongs to the cushion type design, so 20mm is selected to prevent the cushion from bottoming out. The deformation reference thickness T0 is the distance between the deformed surface and the minimum thickness reference after deformation (the plane where the lowest sampling point after deformation is located). The deformation compensation ΔT is the deformation of the contact surface material after being subjected to body pressure. Obviously, the thickness T before deformation is related to the above thickness variables as shown in the attached figure. Figure 2 As shown, there are the following relationships:

[0082] T=T min +T0+ΔT

[0083] The value of ΔT is obtained by substituting T and the target body pressure value at the sampling point into the mathematical model of material mechanical properties obtained in step 4.

[0084] Step 6: Add deformation compensation and fit the surface, as follows:

[0085] The sampling point is translated in the direction of increasing thickness of the contact surface by the distance of deformation compensation ΔT to obtain the fitting point. All the fitting points are used to fit the G1-order continuous smooth surface according to the smoothing requirements of the design. Then, the obtained deformation compensation ΔT is added to the deformed surface, and the fitted surface is the designed flexible contact surface. Figure 7 shown.

[0086] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0087] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0088] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A contact surface design method for target body pressure distribution, characterized in that: The specific steps include: Step 1: Establish a human biomechanical finite element model; Step 2: Apply target body pressure distribution on the body surface; Step 3: Extract the deformed body surface; Step 4: Determine the mechanical properties of the contact surface material; Step 5: Determine the minimum thickness after deformation and the amount of deformation compensation; Step 6: Add deformation compensation and fit the surface; The establishment of the human body biomechanical finite element model described in step 1 specifically includes the following contents: Establishing a human biomechanical finite element model of the target population based on the contact contour to be designed, wherein the contact contour includes bones, muscles, fat, soft tissue or skin, and the human biomechanical finite element model is the entire human body or the part of the human body that is in contact with the contact contour; The target body pressure distribution applied to the body surface in step 2 specifically includes the following: Determine the target body pressure distribution pattern according to design requirements, apply the target body pressure distribution to the human body surface of the human biomechanical finite element model established in step 1 in the form of an isobaric curve, and divide the human body surface into regions with different target body pressure intervals; The target body pressure distribution pattern should be determined so that the integral of the body pressure on the contact contour is equal to the external load that generates the contact body pressure; The extraction of the deformed body surface described in step 3 specifically includes the following: The human biomechanical finite element model with the target body pressure distribution applied in step 2 is submitted to a simulation calculation, and after the calculation is completed, the deformed body surface at the designed contact area is extracted; If the contact surface is rigid, the extracted deformed surface is the designed rigid contact surface; if the contact surface is flexible, the isobaric curve on the deformed surface is retained and step 4 is continued; Determining the mechanical properties of the contact surface material as described in step 4 specifically includes the following: The mechanical properties of the contact surface material include compressive stress-strain relationship, shear stress-strain relationship, elastic hysteresis, viscosity or viscoelasticity, and a mathematical model between material pressure, thickness and deformation is determined based on the mechanical properties of the contact surface material; The compressive stress-strain relationship is obtained by the following method: If the contact surface material has been determined, it can be obtained through uniaxial compression test; If the contact surface material is not determined, simulation is performed using a parameterized material constitutive model, and the appropriate material is selected based on the set parameters; Determining the minimum thickness after deformation and the deformation compensation amount described in step 5 specifically includes the following: The design surface sampling points are extracted from the isobaric pressure curve on the deformed body surface retained in step 3, and the sampling distance is less than the allowable size of the design accuracy; and the following thickness variables are obtained based on the coordinates of the extracted design surface sampling points: the minimum thickness after deformation T min and the deformation reference thickness T0; the minimum thickness after deformation T min The deformation reference thickness T0 is selected based on the design goal or design experience, and is the distance between the deformed surface and the minimum thickness reference after deformation; the minimum thickness reference after deformation is the plane where the lowest sampling point after deformation is located; The deformation compensation ΔT generated by the contact surface material after being subjected to body pressure can be obtained by the following formula: T=T min +T0+ΔT Where T is the thickness before deformation; Adding deformation compensation and fitting the surface as described in step 6 specifically includes the following: The sampling point is translated in the direction of increasing thickness of the contact surface by the deformation compensation amount ΔT to obtain the fitting point. All the fitting points are used to fit a smooth surface with a continuity of not less than G1 order. The obtained deformation compensation amount ΔT is then added to the deformed surface, and the fitted surface is the designed flexible contact surface.

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