Design method of single-sided double-groove section automotive suspension leaf spring

Abstract

This invention relates to the field of automotive suspension component design technology, specifically to a design method for a single-sided double-groove section automotive suspension leaf spring. The method employs a superposition approach, dividing the single-sided double-groove section into a flat plate portion and a grooved portion, calculating the rotational moment of inertia and area of ​​each portion separately, and then superimposing them. By accurately calculating the rotational moment of inertia and area of ​​the single-sided double-groove section leaf spring, this invention can accurately design and calculate the stiffness, deflection, stress, and weight parameters of the single-sided double-groove section automotive suspension leaf spring, meeting the design requirements of automotive suspensions for leaf spring stiffness, deflection, stress, and weight parameters.

Description

Technical Field

[0001] This invention relates to the field of automotive suspension component design technology, specifically to a design method for a single-sided double-groove section automotive suspension leaf spring, applicable to the design calculation of single-sided double-groove section leaf springs for the front and rear suspensions of trucks, engineering vehicles, and mining vehicles. Background Technology

[0002] Leaf springs are common elastic elements in commercial vehicle suspensions, installed between the axle and the vehicle frame. Their core function is to reduce the transmission of impacts and vibrations from the ground to the vehicle body. During operation, a leaf spring experiences tensile stress on one side and compressive stress on the other. For commonly used flat-section leaf springs, the tensile and compressive stresses are equal. Because the tensile strength of the material is significantly lower than its compressive strength, failure always occurs on the tension side. Single-sided double-groove leaf springs, by incorporating a double-groove structure on the compression side and a flat structure on the tension side, shift the neutral layer of the cross-section towards the tension side, thereby reducing the bending stress on the tension side surface and improving service life.

[0003] However, the cross-sectional structure of single-sided double-groove leaf springs is complex, and conventional calculation methods cannot accurately calculate their moment of inertia and cross-sectional area. Existing design methods use rectangular cross-sections and rectangular grooves for approximate calculations, failing to consider the side arcs and the bevel angles and arc transitions of the grooves. This results in significant deviations between the theoretical and actual values ​​of the moment of inertia and cross-sectional area, making it impossible to accurately design and calculate the stiffness, deflection, stress, and weight parameters of the leaf spring, thus affecting the reliability of product design and its performance. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a design method for a single-sided double-groove section automotive suspension leaf spring, which can accurately design and calculate the stiffness, deflection, stress and weight parameters of the single-sided double-groove section automotive suspension leaf spring, so as to meet the design requirements of automotive suspension for the stiffness, deflection, stress and weight parameters of leaf spring.

[0005] The design method for a single-sided double-groove section automotive suspension leaf spring of the present invention adopts the superposition method, which divides the single-sided double-groove section into a flat plate part and a groove part, calculates the rotational moment of inertia and area of ​​the two parts respectively, and then superimposes them, including the following steps:

[0006] S1. Determine the inherent deflection frequency requirement of the leaf spring under full load based on customer requirements and smoothness requirements;

[0007] S2. Based on the design load of the leaf spring. Calculate the stiffness of a leaf spring = ;

[0008] Where F' is the stiffness of the leaf spring, f is the natural deflection frequency of the leaf spring, and g is the acceleration due to gravity;

[0009] S3. Without considering the influence of single-sided double groove, based on the flat plate structure, according to the customer's working length, the requirements for the width of the leaf spring, and the relationship between the thickness and stiffness of the leaf spring, the preliminary calculation of the number of leaf springs and the thickness parameters of the leaf spring is performed.

[0010] Leaf spring rotation angle θ= ;

[0011] Leaf spring deflection = ;

[0012] leaf spring stiffness ;

[0013] Ignoring the rotational moment of inertia of a single-sided double-groove = ;

[0014] ;

[0015] Where M is the bending moment experienced by the corresponding section of the leaf spring, and E is the elastic modulus of the material. This represents the distance from the corresponding section to the center of the leaf spring. The distance between the leaf spring and the center The total moment of inertia of the section at the length position, where L is the effective length of the leaf spring. This represents the number of leaves in the leaf spring. Let be the length of the i-th reed. To disregard the rotational moment of inertia of a single-sided double-groove structure, y is the distance of dS relative to the axis of mass.

[0016] S4. Based on the preliminary calculated sheet thickness, select the corresponding specification of single-sided double-groove material, and calculate the cross-sectional area, distance of the centroid from the upper surface, and moment of inertia of the single-sided double-groove section.

[0017] S41. Considering that the side surface of the actual steel leaf spring cross-section is circular, calculate the area of ​​the flat plate cross-section. ;

[0018] S42. Considering the oblique angle and circular transition of the actual groove, divide the groove into 7 parts: region I, region II, region III, region IV, region V, region VI, and region VII. Calculate the area of ​​each part separately, then superimpose them to calculate the cross-sectional area of ​​the groove shape. ;

[0019] S43. Calculate the cross-sectional area of ​​a single-sided double-groove section. ;

[0020] S44. Calculate the distance from the centroid of a single-sided double-groove section to the upper surface. ;

[0021] S441. Calculate the static moment of the plate section relative to the upper surface. and the static moment of the groove relative to the upper surface ;

[0022] = ;

[0023] = = ;

[0024] in, for The distance relative to the upper surface;

[0025] = ;

[0026] = + + + + + + ;

[0027] in, , , , , , , These are the static moments of each part of the groove relative to the upper surface;

[0028] S442, according to and calculate ;

[0029] S45. Calculate the moment of inertia of a single-sided double-groove section relative to its centroidal axis. ;

[0030] = ;

[0031] = + + + + + + ;

[0032] = -2 ;

[0033] in, To disregard the rotational moment of inertia of a single-sided double-groove, Let be the total moment of inertia of the groove relative to the axis of mass. , , , , , , These are the moments of inertia of each part of the groove relative to the axis of mass;

[0034] S5. Based on the working length, the rotational moment of inertia of the single-sided double-groove material, and the relationship between the length and stiffness of each leaf spring, design and calculate the leaf spring rotation angle θ and leaf spring deflection according to the formula in step S3. and the stiffness of the leaf spring When calculating the rotation angle θ of the leaf spring, Use the following piecewise function;

[0035] ;

[0036] S6. Based on the calculated length, thickness, distance from the centroid of the single-sided double-groove section to the upper surface, and rotational moment of inertia parameters of each leaf spring, calculate and verify the design stress and lug strength of the spring root of the leaf spring.

[0037] Design stress = = ;

[0038] Ear curl strength ;

[0039] in The radius of the curled ear;

[0040] S7. Based on the calculated design stress Ear curl strength Adjust the thickness and length parameters of the leaf springs, recalculate the design stress using iterative calculations, and then re-verify the results. Ear curl strength Until the customer or design requirements are met.

[0041] Preferably, in step S41, the cross-sectional area of ​​the flat plate shape is... The calculation formula is:

[0042] =bh+2 - h(2R- );

[0043] in, Let be the cross-sectional area of ​​the flat plate, b be the width of the leaf spring, h be the thickness of the leaf spring, and R be the radius of the side arc of the leaf spring.

[0044] Preferably, in step S42, the formulas for calculating the area of ​​each part and the cross-sectional area of ​​the groove shape are as follows:

[0045] ;

[0046] = ;

[0047] =r (1- ;

[0048] ( ;

[0049] in, = -2[t-2r(1- ] ;

[0050] ;

[0051] t-2r(1- );

[0052] = ;

[0053] = ;

[0054] ( (1-) ;

[0055] + + + + + + ;

[0056] in, Let t be the groove width, t be the groove depth, and r be the groove transition radius. The angle of the groove.

[0057] Preferably, in step S43, the formula for calculating the cross-sectional area of ​​a single-sided double-groove section is:

[0058] = -2 .

[0059] Furthermore, in step S442, the distance from the centroid of the single-sided double-groove section to the upper surface... The calculation formula is:

[0060] = .

[0061] The beneficial effects of this invention compared to the prior art are:

[0062] The design method for single-sided double-groove section automotive suspension leaf springs described in this invention employs a superposition method. The single-sided double-groove section is divided into a flat plate and a grooved portion. First, the rotational moment of inertia and area of ​​the flat plate and grooved portion are calculated separately. Then, the rotational moments of inertia and areas of the two portions are superimposed. When calculating the rotational moment of inertia and area of ​​the grooved portion, the groove is divided into 7 parts, and the rotational moment of inertia and area of ​​each part are calculated separately, and then superimposed. This invention, by accurately calculating the rotational moment of inertia and area of ​​the single-sided double-groove section automotive suspension leaf spring, can accurately design and calculate the stiffness, deflection, stress, and weight parameters of the single-sided double-groove section automotive suspension leaf spring, meeting the design requirements of automotive suspensions for the stiffness, deflection, stress, and weight parameters of the leaf spring. Attached Figure Description

[0063] Figure 1 This is a structural schematic diagram of a single-sided double-groove steel plate spring cross-section;

[0064] Figure 2 This is a schematic diagram of the groove area of ​​a single-sided double-groove steel plate spring;

[0065] Figure 3 This is a structural diagram of a single-sided double-groove steel leaf spring calculated as a flat plate structure.

[0066] In the diagram: 1. Region I; 2. Region II; 3. Region III; 4. Region IV; 5. Region V; 6. Region VI; 7. Region VII. Detailed Implementation

[0067] Example 1

[0068] like Figure 1-3 As shown, this embodiment is achieved through the following technical solution: The single-sided double-groove section is divided into a flat plate portion and a groove portion using a superposition method. The rotational moment of inertia and area of ​​each portion are calculated separately and then superimposed. This includes the following steps:

[0069] S1. Determine the inherent deflection frequency requirement of the leaf spring under full load based on customer requirements and smoothness requirements;

[0070] S2. Based on the design load of the leaf spring. Calculate the stiffness of a leaf spring = ;

[0071] Where F' is the stiffness of the leaf spring, f is the natural deflection frequency of the leaf spring, and g is the acceleration due to gravity;

[0072] S3. Without considering the influence of single-sided double groove, based on the flat plate structure, according to the customer's working length, the requirements for the width of the leaf spring, and the relationship between the thickness and stiffness of the leaf spring, the preliminary calculation of the number of leaf springs and the thickness parameters of the leaf spring is performed.

[0073] Leaf spring rotation angle θ= ;

[0074] Leaf spring deflection = ;

[0075] leaf spring stiffness ;

[0076] Ignoring the rotational moment of inertia of a single-sided double-groove = ;

[0077] ;

[0078] Where M is the bending moment experienced by the corresponding section of the leaf spring, and E is the elastic modulus of the material. This represents the distance from the corresponding section to the center of the leaf spring. The distance between the leaf spring and the center The total moment of inertia of the section at the length position, where L is the effective length of the leaf spring. This represents the number of leaves in the leaf spring. Let be the length of the i-th reed. To disregard the rotational moment of inertia of a single-sided double-groove structure, y is the distance of dS relative to the axis of mass.

[0079] S4. Based on the preliminary calculated sheet thickness, select the corresponding specification of single-sided double-groove material, and calculate the cross-sectional area, distance of the centroid from the upper surface, and moment of inertia of the single-sided double-groove section.

[0080] S41. Considering that the side surface of the actual steel leaf spring cross-section is circular, calculate the area of ​​the flat plate cross-section. ;

[0081] S42. Considering the oblique angle and arc transition of the actual groove, divide the groove into 7 parts: Region I 1, Region II 2, Region III 3, Region IV 4, Region V 5, Region VI 6, and Region VII 7. Calculate the area of ​​each part separately, then superimpose them to calculate the cross-sectional area of ​​the groove shape. ;

[0082] S43. Calculate the cross-sectional area of ​​a single-sided double-groove section. ;

[0083] S44. Calculate the distance from the centroid of a single-sided double-groove section to the upper surface. ;

[0084] S441. Calculate the static moment of the plate section relative to the upper surface. and the static moment of the groove relative to the upper surface ;

[0085] = ;

[0086] = = ;

[0087] in, for The distance relative to the upper surface;

[0088] = ;

[0089] = + + + + + + ;

[0090] in, , , , , , , These are the static moments of each part of the groove relative to the upper surface;

[0091] S442, according to and calculate ;

[0092] S45. Calculate the moment of inertia of a single-sided double-groove section relative to its centroidal axis. ;

[0093] = ;

[0094] = + + + + + + ;

[0095] = -2 ;

[0096] in, To disregard the rotational moment of inertia of a single-sided double-groove, Let be the total moment of inertia of the groove relative to the axis of mass. , , , , , , These are the moments of inertia of each part of the groove relative to the axis of mass;

[0097] S5. Based on the working length, the rotational moment of inertia of the single-sided double-groove material, and the relationship between the length and stiffness of each leaf spring, design and calculate the leaf spring rotation angle θ and leaf spring deflection according to the formula in step S3. and the stiffness of the leaf spring When calculating the rotation angle θ of the leaf spring, Use the following piecewise function;

[0098] ;

[0099] S6. Based on the calculated length, thickness, distance from the centroid of the single-sided double-groove section to the upper surface, and rotational moment of inertia parameters of each leaf spring, calculate and verify the design stress and lug strength of the spring root of the leaf spring.

[0100] Design stress = = ;

[0101] Ear curl strength ;

[0102] in Where L is the design load of the leaf spring, and L is the effective length of the leaf spring. This is the distance from the centroid of the single-sided double-groove section to the upper surface. This represents the number of leaves in a leaf spring. Let be the moment of inertia of the single-sided double-groove section relative to the axis of mass. The radius of the curled ear;

[0103] S7. Based on the calculated design stress Ear curl strength Adjust the thickness and length parameters of the leaf springs, recalculate the design stress using iterative calculations, and then re-verify the results. Ear curl strength Until the customer or design requirements are met.

[0104] In this embodiment, in step S41, the cross-sectional area of ​​the flat plate shape is... The calculation formula is:

[0105] =bh+2 - h(2R- );

[0106] in, Let be the cross-sectional area of ​​the flat plate, b be the width of the leaf spring, h be the thickness of the leaf spring, and R be the radius of the side arc of the leaf spring.

[0107] In step S42, the formulas for calculating the area of ​​each part and the cross-sectional area of ​​the groove shape are as follows:

[0108] ;

[0109] = ;

[0110] =r (1- ;

[0111] ( ;

[0112] in, = -2[t-2r(1- ] ;

[0113] ;

[0114] t-2r(1- );

[0115] = ;

[0116] = ;

[0117] ( (1-) ;

[0118] + + + + + + ;

[0119] in The cross-sectional area of ​​the groove shape is... Let t be the groove width, t be the groove depth, and r be the groove transition radius. The angle of the groove.

[0120] In step S43, the formula for calculating the cross-sectional area of ​​a single-sided double-groove section is:

[0121] = -2 .

[0122] In step S442, the distance from the centroid of the single-sided double-groove section to the upper surface is... The calculation formula is:

[0123] = .

[0124] In step S5, when designing the leaf spring, the length parameters of each leaf spring are calculated based on the design input parameters such as stiffness, width, number of leaves, and load, according to the correspondence between the length of each leaf spring and the stiffness of the leaf spring. In actual calculation, a calculation program can be written using Visual Studio C++ according to the design calculation requirements, and the length parameters of each leaf spring can be calculated quickly and accurately through iteration.

[0125] Example 2

[0126] According to the present invention, a leaf spring for the front suspension of a truck is designed and calculated, and the design load of the leaf spring is... =23520N, width b=90mm, working length L=1600mm, lug radius =36mm, design a single-sided double-groove section automotive suspension leaf spring, the steps are as follows:

[0127] 1. Based on customer requirements and smoothness requirements, the inherent deflection frequency requirement of the leaf spring under full load is determined to be 1.6-1.7Hz;

[0128] 2. According to the relationship between stiffness and suspension frequency: = The calculated stiffness of the leaf spring is 243-274 N / mm.

[0129] 3. Without considering the influence of single-sided double groove, based on the flat plate structure, according to the customer's requirement of 1600mm for the working length and 90mm for the leaf spring width, and based on the relationship between the working length, leaf spring width, leaf thickness and stiffness, the preliminary calculation is that there are 9 leaf springs with a leaf thickness of 13mm.

[0130] 4. Based on the preliminary calculation of a leaf spring thickness of 13mm and a required width of 90mm, select 13x90mm single-sided double-groove material and calculate the cross-sectional area of ​​the single-sided double-groove. =1026.9 The distance from the centroid of a single-sided double-groove section to the upper surface =6.0757mm and the moment of inertia of the single-sided double-groove section relative to the center of mass axis =13577.4 The preliminary calculation results are shown in Table 1:

[0131]

[0132] Table 1

[0133] 5. Based on the working length, the moment of inertia of the single-sided double-groove material, and the relationship between the length and stiffness of each leaf spring, a calculation program was written using Visual Studio C++ to accurately and quickly calculate the length parameters of each leaf spring through iteration; the accurate calculation results are shown in Table 2:

[0134]

[0135] Table 2

[0136] 6. Calculate and verify the design stress of the spring at the root of the steel plate and the strength of the coil lug;

[0137] Design stress = 468MPa, which meets the requirements;

[0138] Ear curl strength = 288MPa, which meets the requirements;

[0139] 7. Based on the length of each piece, the cross-sectional area of ​​the single-sided double groove. Accurately calculate the weight of the leaf spring.

[0140] The leaf springs for the front suspension of trucks designed and calculated according to this invention have passed performance testing and trial installation, and have been installed in small batches.

Claims

1. A design method for a single-sided double-groove section automotive suspension leaf spring, characterized in that, The superposition method is used to divide the single-sided double-groove section into a flat plate part and a groove part. The rotational moment of inertia and area of ​​the two parts are calculated separately and then superimposed. The method includes the following steps: S1. Determine the inherent deflection frequency requirement of the leaf spring under full load based on customer requirements and smoothness requirements; S2. Based on the design load of the leaf spring. Calculate the stiffness of a leaf spring = ; Where F' is the stiffness of the leaf spring, f is the natural deflection frequency of the leaf spring, and g is the acceleration due to gravity; S3. Without considering the influence of single-sided double groove, based on the flat plate structure, according to the customer's working length, the requirements for the width of the leaf spring, and the relationship between the thickness and stiffness of the leaf spring, the preliminary calculation of the number of leaf springs and the leaf thickness parameters is performed. Leaf spring rotation angle θ= ; Leaf spring deflection = ; Leaf spring stiffness ; Ignoring the rotational moment of inertia of a single-sided double-groove = ; ； Where M is the bending moment experienced by the corresponding section of the leaf spring, and E is the elastic modulus of the material. This represents the distance from the corresponding section to the center of the leaf spring. The distance between the leaf spring and the center The total moment of inertia of the section at the length position, where L is the effective length of the leaf spring. This represents the number of leaf springs. Let be the length of the i-th reed. To disregard the rotational moment of inertia of a single-sided double-groove structure, y is the distance of dS relative to the axis of mass. S4. Based on the preliminary calculated sheet thickness, select the corresponding specification of single-sided double-groove material, and calculate the cross-sectional area, distance of the centroid from the upper surface, and moment of inertia of the single-sided double-groove section. S41. Considering that the side surface of the actual steel leaf spring cross-section is circular, calculate the area of ​​the flat plate cross-section. ; S42. Considering the oblique angle and arc transition of the actual groove, the groove is divided into 7 parts: region I (1), region II (2), region III (3), region IV (4), region V (5), region VI (6), and region VII (7). The area of ​​each part is calculated separately, and then the parts are superimposed to calculate the cross-sectional area of ​​the groove shape. ; S43. Calculate the cross-sectional area of ​​a single-sided double-groove section. ; S44. Calculate the distance from the centroid of a single-sided double-groove section to the upper surface. ; S441. Calculate the static moment of the plate section relative to the upper surface. and the static moment of the groove relative to the upper surface ; = ； = = ； in, for The distance relative to the upper surface; = ； = + + + + + + ； in, , , , , , , These are the static moments of each part of the groove relative to the upper surface; S442, according to and calculate ; S45. Calculate the moment of inertia of a single-sided double-groove section relative to its centroidal axis. ; = ； = + + + + + + ； = -2 ； in, To disregard the rotational moment of inertia of a single-sided double-groove, Let be the total moment of inertia of the groove relative to the axis of mass. , , , , , , These are the moments of inertia of each part of the groove relative to the axis of mass; S5. Based on the working length, the rotational moment of inertia of the single-sided double-groove material, and the relationship between the length and stiffness of each leaf spring, design and calculate the leaf spring rotation angle θ and leaf spring deflection according to the formula in step S3. and the stiffness of the leaf spring When calculating the rotation angle θ of the leaf spring, Use the following piecewise function; ； S6. Based on the calculated length, thickness, distance from the centroid of the single-sided double-groove section to the upper surface, and rotational moment of inertia parameters of each leaf spring, calculate and verify the design stress and lug strength of the spring root of the leaf spring. Design stress = = ; Ear curl strength ; in The radius of the curled ear; S7. Based on the calculated design stress Ear curl strength Adjust the thickness and length parameters of the leaf springs, recalculate iteratively, and then re-verify the design stress. Ear curl strength Until the customer or design requirements are met.

2. The design method for a single-sided double-groove section automotive suspension leaf spring according to claim 1, characterized in that, In step S41, the cross-sectional area of ​​the flat plate shape The calculation formula is: =b+2 - h(2R- ); in, Let be the cross-sectional area of ​​the flat plate, b be the width of the leaf spring, h be the thickness of the leaf spring, and R be the radius of the side arc of the leaf spring.

3. The design method for a single-sided double-groove section automotive suspension leaf spring according to claim 1, characterized in that, In step S42, the formulas for calculating the area of ​​each part and the cross-sectional area of ​​the groove shape are as follows: ； = ； =r (1- ； ( ； in, = -2[t-2r(1- ] ; ； t-2r(1- )； = ； = ； ( )(1- ； + + + + + + ； in, Let t be the groove width, t be the groove depth, and r be the groove transition radius. The angle of the groove.

4. The design method for a single-sided double-groove section automotive suspension leaf spring according to claim 1, characterized in that, In step S43, the formula for calculating the cross-sectional area of ​​a single-sided double-groove section is: = -2 。 5. The design method for a single-sided double-groove section automotive suspension leaf spring according to claim 1, characterized in that, In step S442, the distance from the centroid of the single-sided double-groove section to the upper surface is... The calculation formula is: = 。

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