JPWO2008012876A1 - Shock absorbing member - Google Patents

Abstract

The whole is made of one or more metal materials of aluminum alloy, magnesium alloy, iron, and steel, and the vertical cross-sectional shape of the side wall is corrugated, and the cross-sectional shape is circular, oval, and rounded corners. An impact-absorbing member that has a cylindrical body portion (11) that is any one of the squares and deforms in response to an impact load, and when the cross-sectional shape of the cylindrical body portion (11) is the circular shape, In the case of other than a circle, the radius of a circle having the same circumference as the average length of the outer circumference thereof is R, the thickness of the cylindrical body portion (11) is t, and the waveform formed in the cylindrical body portion (11). Where t / R is not less than 0.0150, a / R is not less than 0.036, and λ / R is not less than 0.2 and not more than 0.89. When the body part (11) is pressed from at least one end at a constant speed, the waveform excluding both end parts is uniformly deformed, and the tubular body part The instantaneous decrease in the load received by (11) has a load fluctuation within 10% of the maximum load received before that, and the load received by the cylindrical portion (11) increases monotonously.

Description

The present invention relates to an impact absorbing member capable of effectively absorbing impact energy by plastic deformation, and more specifically, for example, absorbing an impact at the time of a car collision to ensure the safety of an occupant and give it to a vehicle body. The present invention relates to an impact absorbing member capable of reducing damage.

Conventionally, for example, an impact absorbing member to be mounted on an automobile is generally constituted by a cylindrical body made of iron sheet metal or aluminum extruded material. However, such an impact absorbing member has a drawback that a load peak appears in the initial stage of receiving an impact, so that damage to the passenger and the vehicle body is large.
Therefore, in order to ensure the safety of the passenger at the time of collision and reduce damage to the vehicle body, the following requirements are required for the impact absorbing member.
a) To reduce the load peak that occurs in the initial stage.
b) The region where the load decreases in the amplitude of the generated load means a decrease in the impact energy absorption efficiency. Therefore, the instantaneous decrease amount of the load is reduced to increase the load monotonously, and the impact energy absorption efficiency is increased. Make it good.
As such an impact absorbing member, an aluminum extrusion mold material having a swell formed on its surface (see, for example, Japanese Patent Laid-Open No. 6-344023), and a vehicle shock absorber having an accordion shape (for example, Japan) JP 2002-104107 A) is disclosed.

The shock absorbing member having the above-described swell or bellows shape can reduce the peak of the load that occurs in the initial stage. However, such shock absorbing members may be unstablely deformed depending on the shape of the formed corrugation, and the amount of instantaneous decrease in load may not be sufficiently reduced. The impact energy absorption performance was not sufficient.

The present invention has been made in view of such circumstances. When an impact load is received, the peak of the load that occurs in the initial stage can be reduced, and the instantaneous decrease in the load received by the impact absorbing member can be suppressed more than before. Then, it aims at providing the impact-absorbing member excellent in the impact energy absorption performance.

The impact-absorbing member according to the first invention that meets the above-mentioned object is entirely made of one or more metal materials of aluminum alloy, magnesium alloy, iron, and steel, and the longitudinal sectional shape of the side wall is corrugated, A cross-sectional shape is a shock absorbing member that has a cylindrical body portion that is any one of a circle, an oval, and a square with rounded corners, and deforms in response to an impact load,
When the cross-sectional shape of the cylindrical body is the circular shape, the average radius thereof, and when the cross-sectional shape is other than the circular shape, R represents a circular radius having the same circumference as the average length of the outer periphery thereof, and the thickness of the cylindrical body portion. T / R is 0.0150, where t is the waveform wavelength before the deformation, that is, the wavelength of the waveform formed in the cylindrical portion at the time of manufacture (unused state) is λ, and the amplitude of the waveform is a. As described above, when a / R is 0.036 or more and λ / R is 0.2 or more and 0.89 or less and the cylindrical body portion is pressed at a constant speed from at least one end, the waveform excluding both end portions is uniformly deformed. In addition, the instantaneous decrease amount of the load received by the cylindrical body portion has a load fluctuation within 10% of the maximum load previously received, and the load received by the cylindrical body portion increases monotonously.
As described above, the shock absorbing member has the cylindrical body portion having the corrugated vertical cross-sectional shape of the side wall. Therefore, the shock absorbing member induces bellows-like plastic deformation in the cylindrical body portion, and is generated at the initial stage when receiving an impact load. The load peak can be reduced as compared with the prior art. Moreover, since the waveform of the cylindrical portion is uniformly deformed and the amount of instantaneous decrease in the load received by the cylindrical portion can be reduced as compared with the conventional case, the impact energy absorption performance can be improved as compared with the conventional case.
Thereby, when this impact absorbing member is installed in, for example, an automobile, the impact absorbing member absorbs an impact at the time of collision of the automobile, ensuring the safety of the passenger and reducing the damage to the vehicle body.

In the impact absorbing member according to the present invention, it is preferable that the t / R, a / R, and λ / R satisfy the following relationship.
(1) When t / R is 0.0150 or more and 0.0179 or less, a / R: 0.054 or more, λ / R: 0.2 or more and 0.4 or less (2) t / R exceeds 0.0179 When 0.0357 or less, a / R: 0.036 or more, λ / R: 0.2 or more and 0.5 or less (3) When t / R is more than 0.0357 and 0.0537 or less, a / R: 0.036 or more, λ / R: 0.2 or more and 0.65 or less (4) When t / R is more than 0.0537 and 0.0714 or less, a / R: 0.036 or more, λ / R: 0. 2 or more and 0.89 or less (5) When t / R is more than 0.0714, a / R: 0.036 or more, λ / R: 0.2 or more and 0.89 or less. The shock absorbing member can be easily designed according to the required size of the cylindrical portion and its thickness.

In the impact absorbing member according to the present invention, it is preferable that the cylindrical portion is a casting.
Thereby, since the freedom degree of the shape of the cylinder part which can be formed becomes high, the shaping | molding of the waveform to a cylinder part can be made easy.
In addition, the shock absorbing member is attached to other parts by the flange portion, and the flange portion and the cylindrical body portion can be easily formed integrally.
And since a cylinder part does not need to perform machining at the time of waveform shaping, it can manufacture a cylinder part, without generating work hardening in a cylinder part. Thereby, in use of an impact-absorbing member, a cylinder part performs the deformation | transformation which was stabilized.

In the impact absorbing member according to the present invention, the portion excluding both sides of the cylindrical body portion is provided along one or both of the inner periphery and the outer periphery of the cylindrical body portion, and against the deformation of the cylindrical body portion. It is preferable that one or a plurality of reinforcing members capable of holding the cross-sectional shape of the cylindrical body portion be provided.
Thereby, a cylinder part performs a stable deformation | transformation, for example, without buckling.

It is a sectional side view of the impact-absorbing member which concerns on 1st Example of this invention. (A)-(D) is explanatory drawing which shows the deformation | transformation state of the cylinder part of an impact-absorbing member, respectively. (A), (B) is explanatory drawing which shows the relationship between the shape of the cylinder part of an impact-absorbing member, and a deformation mode, respectively. (A), (B) is explanatory drawing which shows the relationship between the shape of the cylinder part of an impact-absorbing member, and a deformation mode, respectively. It is explanatory drawing which shows the relationship between the shape of the cylinder part of an impact-absorbing member, and a deformation mode. It is explanatory drawing which shows the relationship between the load and the displacement which the cylinder part of the impact-absorbing member received. It is explanatory drawing which shows the relationship between the load and the displacement which the cylindrical part of the impact-absorbing member which concerns on 2nd Example of this invention received. It is explanatory drawing which shows the relationship between the load and the displacement which the cylindrical part of the impact-absorbing member which concerns on 3rd Example of this invention received.

Subsequently, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIG. 1, the shock absorbing member 10 according to the first embodiment of the present invention is made of a metal material and cut along a longitudinal sectional shape of a side wall (that is, a plane including the axis of the shock absorbing member 10). It has a cylindrical body portion 11 having a corrugated side wall shape and is deformed by receiving an impact load. When the cylindrical portion 11 is pressed from at least one end at a constant speed, the waveform excluding both ends is uniformly deformed, and the instantaneous decrease in the load received by the cylindrical portion 11 is 10% of the maximum load received before that. The load received by the cylindrical body portion 11 increases monotonously with a load fluctuation within. These will be described in detail.

The cylinder part 11 is a casting, and the metal material forming the cylinder part 11 is any one or more of an aluminum alloy, a magnesium alloy, iron, and steel. Specifically, the performance of the metal material is, for example, a 0.2% proof stress of about 100 to 400 MPa, a tensile strength of about 200 to 600 MPa, and an elongation of about 10 to 40%.
Here, when the cylinder part 11 is an aluminum alloy casting, it is lightweight and excellent in impact energy absorption efficiency. Moreover, in the case of a magnesium alloy casting, since the specific gravity is small compared with another metal material, it is the lightest. And in the case of an iron casting, it is inexpensive and economical. Furthermore, in the case of a steel casting, since it is excellent in strength and ductility, it is possible to absorb a large impact energy as compared with other metal materials.

On both sides of the cylindrical body portion 11 of the shock absorbing member 10, flanges that maintain the cross-sectional shape when the cylindrical body portion 11 is deformed (that is, the shape cut by a plane orthogonal to the axial center of the cylindrical body portion 11). Parts 12 and 13 are provided. Since the cylindrical part 11 is a casting, the flange parts 12 and 13 can be manufactured integrally with the cylindrical part 11. In this case, the impact absorbing member 10 is manufactured, for example, by die casting or sand casting using a conventionally known core.
In addition, you may manufacture a cylinder part and a flange part separately, and may join by welding, for example. In this case, you may make each metal material which comprises a cylinder part and a flange part into a different kind.

The cylindrical portion 11 has a circular cross-sectional shape, and the maximum outer diameter D and the minimum inner diameter d are the same from one side to the other side, and the same thickness (thickness) t. It is configured.
The cross-sectional shape of the cylindrical portion may be oval (for example, oval or oval) or square (for example, a polygon such as a triangle or pentagon, a square, or a rectangle). Here, when the cross-sectional shape of the cylindrical body portion is a square, the corner portion is chamfered in a plan view to provide a roundness.
In addition, the circular cylindrical portion may have a tapered shape with a diameter reduced from one side to the other side of the cylindrical portion, and in the case of an oval or a rectangular shape, the inner width is set to one side of the cylindrical portion. It is good also as the shape shrunk | reduced from one side to the other side.
Here, in the case of the taper shape, the taper angle, that is, the inclination angle of the side wall with respect to the one end face of the cylindrical body portion is set to, for example, about 60 degrees or more and less than 90 degrees.
Then, the thickness of the cylindrical body portion is gradually reduced from one side to the other side of the cylindrical body portion, or partially thinned (for example, the central portion in the longitudinal direction is thinner than the other portions). May be.

The average radius (that is, half of the average value φ of the maximum outer diameter D and the minimum inner diameter d) R of the cylindrical body portion 11 is, for example, about 20 mm to 70 mm, and the wall thickness t is, for example, 0. It is about 5 mm or more and 10 mm or less. In addition, when the cross-sectional shape of a cylinder part is other than a circle, ie, when it is an oval or a square, the radius of the circle which has the circumference same as the average length of the outer periphery is made into the above-mentioned magnitude | size. Moreover, the thickness of the flange parts 12 and 13 is about 2 mm or more and 50 mm or less.
Regarding the axial length of the cylindrical portion 11, for example, when the impact absorbing member 10 is used for a stay (fixed portion) of a bumper of an automobile, the axial length of the cylindrical portion 11 is 50 mm or more and 400 mm or less. However, the present invention is not limited to this. However, if the length of the cylindrical portion 11 becomes too long (for example, 500 mm or more), the impact absorbing member 10 may receive an impact load, and the cylindrical portion 11 may be bent.

Therefore, as shown in FIG. 1, a disk-shaped reinforcing member 14 is formed along the inner periphery of the cylindrical portion 11 in a portion excluding both sides of the cylindrical portion 11 (here, the central portion in the axial direction of the cylindrical portion 11). Is provided. The thickness of the reinforcing member 14 is about 5 mm or more and 20 mm or less. The reinforcing member 14 may be manufactured separately from the cylindrical body 11 and connected by, for example, welding, but it is preferable to manufacture the reinforcing member 14 integrally with the cylindrical body 11. Furthermore, a ring-shaped reinforcing member may be provided along the outer periphery of the cylindrical body portion, or only this ring-shaped reinforcing member may be provided.
By providing the reinforcing member 14, the shape of the cylindrical body portion 11 can be maintained without breaking the circular shape of the cross section.
Note that a plurality of reinforcing members may be provided according to the length of the cylindrical body portion, and may not be provided if the length of the cylindrical body portion is short.

The waveform of the side wall of the cylindrical part 11 has a shape in which a constant amplitude is repeatedly formed at a constant period. This waveform is, for example, a sine curve (y = a · sin (2πλ) x, where a is the amplitude of the waveform, λ is the wavelength of the waveform, and x is the length of the side wall), triangular wave, jagged wave, arc and straight line Can be formed by combining waves.
When the cylindrical body portion 11 having such a shape is pressed from one end thereof at a constant speed along the axial center of the cylindrical body portion 11, a U-shaped cross section that forms a bellows-like plastic deformation, that is, a waveform, on the cylindrical body portion 11. Or V-shaped protrusions 15 and 16 are crushed (that is, bent near the apex), and the following deformation modes appear as the shape.
(A) Deformation mode in which bellows-like plastic deformation occurs without following the waveform shape.
(B) A deformation mode in which the bellows-shaped plastic deformation is deformed along the waveform shape, but the plurality of protrusions are sequentially crushed one by one.
(C) A deformation mode in which the bellows-shaped plastic deformation is deformed along the waveform shape, and the plurality of protrusions are crushed substantially at the same time.

Here, the schematic diagram of the waveform of the cylindrical part deformed in each of the deformation modes (a) to (c) described above is shown in FIGS. 2 (A) to 2 (D) are schematic diagrams showing the shape of the cylindrical body before the deformation, and in the schematic diagram shown by the solid line, the deformation of the cylindrical body part proceeds from the left side to the right side of FIG. It is the cross-sectional shape of the cylinder part in the middle of a deformation | transformation at the time of doing. In addition, when the cylinder part in which the waveform is not provided is pressed from one end, wrinkles may be regularly formed and may be crushed. It has been found that the wavelength of this wrinkle is determined only by the radius and the thickness of the cylindrical part, regardless of the material properties of the cylindrical part.
As a deformation mode (a), as shown in FIG. 2 (A), the wavelength of the waveform provided in the cylindrical portion is larger than the wavelength of wrinkles generated in the cylindrical portion when there is no waveform. In the case where a wrinkle or wrinkle is formed, or as shown in FIG. 2B, the wrinkle wavelength is smaller than the wavelength of the wrinkle generated in the cylindrical portion when there is no corrugation. .
In the deformation mode (b), as shown in FIG. 2 (C), wrinkles are generated along the waveform, and the waveform of the cylindrical portion is sequentially collapsed one by one.
As shown in FIG. 2D, the deformation mode (c) is a deformation in which wrinkles are generated along the waveform, and the waveform of the cylindrical portion is simultaneously crushed. Here, the term “simultaneously” includes a range in which the variation in deformation of each protrusion is 3% or less (more than 2%) of the total time required for deformation of all protrusions.

In order to realize the deformation mode (c) excellent in shock absorbing performance, the cylindrical part is made of an aluminum alloy of JIS AC4CH-T4 (0.2% proof stress: 87 MPa, tensile strength: 192 MPa, elongation: 18%). Using a cylindrical body, numerical crushing analysis (by the finite element method) was performed by pressing this cylindrical body from one end at a constant speed to crush it, and the shape of the cylindrical portion where the deformation mode occurs was examined. In this examination, the average radius (R) of the cylindrical part, the thickness (t) of the cylindrical part, the wavelength (λ) of the waveform formed in the cylindrical part, and the amplitude (a) of the waveform are used. Then, the thickness (t / R) of the cylindrical portion relative to the radius of the cylindrical portion, the amplitude (a / R) of the waveform, and the wavelength (λ / R) of the waveform were investigated. Here, the waveform wavelength is obtained by dividing the interval between the apexes of adjacent protrusions, that is, the length of the cylindrical part when not in use, by the number of outer protrusions 15 or inner protrusions 16 formed on the cylindrical part. The amplitude of the waveform means the amount of protrusion to the outside of the cylindrical portion based on the average value of the maximum outer diameter and the maximum inner diameter of the cylindrical portion, that is, the degree of swelling.

Hereinafter, when R is 56 mm, and t is 1.0, 2.0, 3.0, 4.0, 5.0, and 5.0 mm, λ is in the range of 13 to 52 mm, and a is The result changed in the range of 1 to 5 mm will be described. This analysis result shows that t (t / R), a / R, and λ / R are three axes (x-axis direction, y-axis direction, z-axis direction) under the condition that (t / R) is 0.0150 or more. However, for convenience of explanation, a / R and λ / R when t is 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm, and 5.0 mm. The relationship will be described with reference to FIGS. 3 (A), 3 (B), 4 (A), 4 (B), and FIG. In the figure, the deformation modes (a) to (c) correspond to the respective deformation modes described above, and the deformation mode (d) is mostly the deformation mode (c). This means a portion where the deformation mode (b) may also occur locally.

As shown in FIG. 3A, when t is set to 1.0 mm and the thickness is reduced with respect to the radius of the cylindrical portion (t / R = 0.0179), the outward expansion of the cylindrical portion is caused. By enlarging and increasing the number of protrusions formed on the same length of the cylindrical portion (that is, by reducing λ), the deformation mode (c) described above can be expressed in the cylindrical portion. .
Next, as shown in FIG. 3 (B), when t is 2.0 mm and the thickness with respect to the radius of the cylindrical portion is made thicker than in FIG. 2 (A) (t / R = 0.0357). The deformation mode (c) described above is applied to the cylindrical portion even if the bulge to the outside of the cylindrical portion is reduced and the number of protrusions formed on the cylindrical portion is reduced (that is, λ is increased). Can be expressed.
As shown in FIG. 4A, when t is set to 3.0 mm and the thickness with respect to the radius of the cylindrical portion is further increased (t / R = 0.0537), the protruding portion formed in the cylindrical portion. Even if the number is further reduced, the deformation mode (c) described above can be expressed in the cylindrical body portion.

Further, as shown in FIG. 4B, when t is set to 4.0 mm and the thickness with respect to the radius of the cylindrical body portion is further increased (t / R = 0.0714), the protrusion formed on the cylindrical body portion. Even if the number of parts is further reduced, the deformation mode (c) described above can be expressed in the cylindrical part.
Furthermore, as shown in FIG. 5, when t is 5.0 mm and the thickness of the cylindrical portion is further increased (t / R = 0.0893), the thickness becomes too thick, so that the protruding portion is It becomes difficult to bend, and the region where the above-described deformation mode (c) can be expressed in the cylindrical body portion cannot be further expanded.
From the above results, in order to develop the deformation mode (c) described above in the cylindrical part, t / R is 0.0150 or more, a / R is 0.036 or more, and λ / R is 0.2 or more and 0. It is necessary to satisfy the condition of 89 or less.
More specifically, it is preferable to satisfy the following conditions.

(1) When t / R is 0.0150 or more and 0.0179 or less, a / R is more than 0.054 (preferably 0.06 or more, more preferably 0.07 or more), and λ / R is 0.2 or more and 0.4 or less (preferably, lower limit is 0.25, upper limit is 0.35).
(2) When t / R is more than 0.0179 and not more than 0.0357, a / R is set to 0.036 or more (preferably 0.04 or more, more preferably 0.05 or more), and λ / R is set to 0.2 or more and 0.5 or less (preferably, the lower limit is 0.22 and the upper limit is 0.45).
(3) When t / R is more than 0.0357 and not more than 0.0537, a / R is set to 0.036 or more (preferably 0.04 or more, more preferably 0.05 or more), and λ / R is set to 0.2 or more and 0.65 or less (preferably, lower limit is 0.25, upper limit is 0.5 or 0.45).

(4) When t / R is more than 0.0537 and 0.0714 or less, a / R is set to 0.036 or more (preferably 0.04 or more, more preferably 0.05 or more), and λ / R is set to 0.2 or more and 0.89 or less (preferably, lower limit is 0.25, upper limit is 0.5 or 0.45).
(5) When t / R exceeds 0.0714, a / R is set to 0.036 or more (preferably 0.04 or more, more preferably 0.05 or more), and λ / R is set to 0.2 or more. 0.89 or less (preferably, the lower limit is 0.3, and the upper limit is 0.7 or 0.5).

In the above conditions (1) to (5), the upper limit value of a / R is not described. This is because if the a / R is increased, the outward bulge of the cylindrical body portion becomes too large, so that the cylindrical body portion is easily crushed and the deformation mode (c) can be easily expressed.
However, in this case, since the impact absorbing member cannot sufficiently receive the impact load, it is preferable to set a / R to 0.15 or less, and further to 0.10 or less in use.
In addition, when the cylinder part is the same diameter from the one side to the other side, the shape of a cylinder part is prescribed | regulated by adapting the radius to above-mentioned conditions. Further, when the cylindrical portion is tapered, the shape of the cylindrical portion is defined by adapting the larger radius to the above-described conditions. This is because the above-described deformation mode is easily influenced by a large radius. In this case, it is preferable that the shape of the cylindrical portion is defined by adapting the radius of the cylindrical portion at an arbitrary position in the axial direction to the above-described conditions.

In this way, by defining the shape of the cylindrical body portion 11, when the shock absorbing member 10 is used, when the cylindrical body portion 11 is deformed, both end portions (that is, portions connected to the flange portions 12 and 13). The waveform excluding the vicinity: for example, the range from the end of the cylindrical portion 11 to about 10 mm) can be uniformly deformed. Here, uniform deformation means that 80% or more (preferably 90% or more) of the entire waveform formed in the cylindrical body portion 11 is deformed.
At this time, the instantaneous decrease amount of the load received by the cylindrical body portion 11 can be made within 10% (preferably 7%, more preferably 5%) of the maximum load received before that.
As a result, the load received by the cylinder body monotonously increases while having a smaller load variation than the conventional one.

Next, in the result of the numerical crush analysis described above, the relationship between the load and the displacement of the cylindrical part when the radius of the cylindrical part is 56 mm, the wall thickness is 2 mm, and 3 mm is described with reference to FIG. While explaining. Here, the wavelength (λ) of the waveform formed in the cylindrical portion, the amplitude (a) of the waveform, the thickness (t / R) of the cylindrical portion relative to the radius of the cylindrical portion, and the wavelength (a / R) of the waveform ) And the amplitude (λ / R) of the waveform are shown in Table 1, respectively.

As is clear from FIG. 6 and Table 1, in Examples 1 to 4 in which the shape of each cylindrical portion satisfies the conditions that allow the deformation mode (c) to be expressed, instantaneous reduction in the load received by the cylindrical portion is achieved. It was confirmed that the load received by the cylinder body monotonously increased with the load fluctuation within 10% of the maximum load received before that.
On the other hand, for Comparative Examples 1 and 2 that do not satisfy the conditions that allow the deformation mode (c) to be expressed, the instantaneous decrease in the load received by the cylindrical portion is 20% or more of the maximum load received before that. The load fluctuated and the amount of instantaneous decrease was insufficient.

Subsequently, a crushing experiment was performed using the cylindrical portion of the impact absorbing member according to the second and third embodiments of the present invention, and the result of investigating the relationship between the load and displacement of the cylindrical portion is shown in FIG. This will be described with reference to FIG. In this experiment, a load is applied at a constant speed from one end to a cylindrical body made of an aluminum alloy cylinder having the above-mentioned material characteristics, and the load received at that time is deformed by a load cell. This was done by measuring the amount of displacement of the cylindrical part with a displacement meter.
The cylindrical portion of the shock absorbing member according to the second embodiment used in the crushing experiment shown in FIG. 7 has an axial length of 130 mm, a radius of 56 mm, a thickness of 3.5 mm, and a wavelength of 16. 67 mm, amplitude: 3 mm, (t / R): 0.0625, (a / R): 0.054, (λ / R): 0.30. Moreover, the cylinder part of the impact-absorbing member according to the third example used in the crushing experiment shown in FIG. 8 has an axial length of 130 mm, a radius of 56 mm, a thickness of 4 mm, a wavelength of 19.23 mm, Amplitude: 3 mm, (t / R): 0.0714, (a / R): 0.054, (λ / R): 0.34.
Thus, the shape of each cylindrical body part satisfies the conditions under which the above-described deformation mode (c) can be exhibited.

First, the cylindrical part of the impact absorbing member according to the second embodiment will be described.
As apparent from FIG. 7, when the cylindrical body portion receives a load, the load decreases monotonically at three locations x1 to x3, but the load increases monotonously as a whole. Moreover, the point which shows the maximum load before each point x1-x3 in which the load fell was X1-X3. Here, the displacement amount and the maximum load of the cylindrical portion at each point X1 to X3, the displacement amount of the cylindrical portion at the points x1 to x3 at which the load is reduced, and the load with respect to the maximum load at each point X1 to X3. Table 2 shows the amount of decrease (instantaneous decrease amount) and the load fluctuation of the instantaneous decrease amount with respect to the maximum load.

As is apparent from Table 2, the load decrease amount at each point x1 to x3 was about 3 kN at the maximum, and this load fluctuation was about 3% of the maximum load.
As described above, it was confirmed that the load received by the cylinder body can be monotonously increased while suppressing the instantaneous decrease in the load received by the cylinder body.

Next, the cylindrical part of the impact absorbing member according to the third embodiment will be described.
As apparent from FIG. 8, when the cylindrical body portion received a load, the load decreased monotonously at six locations y <b> 1 to y <b> 6, but the load increased monotonically as a whole. The point indicating the maximum load before the points y1 to y3 where the load is reduced is Y1, the point indicating the maximum load before each point y4, y5 is Y4, and the point indicating the maximum load before the point y6 is Y6. Met. Here, the displacement amount and the maximum load of the cylindrical portion at each of the points Y1, Y4, and Y6, the displacement amount of the cylindrical portion at the points y1 to y6 where the load is reduced, and the maximum of each point Y1, Y4, and Y6 Table 3 shows the load decrease amount (instantaneous decrease amount) with respect to the load and the load fluctuation of the instantaneous decrease amount with respect to the maximum load.

As apparent from Table 3, the load decrease amount at each point y1 to y6 was about 10 kN at the maximum, and this load fluctuation was about 8% (within 10%) of the maximum load.
As described above, it was confirmed that the load received by the cylindrical body portion can be monotonously increased while suppressing the instantaneous decrease in the load received by the cylindrical body portion.
As a result, it was confirmed that, for example, an impact at the time of a car collision can be absorbed to ensure the safety of the occupant and to reduce damage to the vehicle body.

As mentioned above, although the embodiment of the present invention has been described, the present invention is not limited to this embodiment, and can be changed without changing the gist of the invention. A part or all of the examples may be combined.

Since the shock absorbing member according to the present invention has a cylindrical body portion having a corrugated vertical cross-sectional shape, the bellows-like plastic deformation is induced in the cylindrical body portion and is generated at the initial stage when receiving an impact load. The load peak can be reduced as compared with the prior art. Moreover, since the waveform of the cylindrical portion is uniformly deformed and the amount of instantaneous decrease in the load received by the cylindrical portion can be reduced as compared with the conventional case, the impact energy absorption performance can be improved as compared with the conventional case. As a result, the impact absorbing member according to the present invention is applied to an automobile, and the impact can be efficiently reduced.

Claims (4)

The whole is made of one or more metal materials of aluminum alloy, magnesium alloy, iron, and steel, and the vertical cross-sectional shape of the side wall is corrugated, and the cross-sectional shape is circular, oval, and rounded corners. A shock absorbing member that has a cylindrical body portion that is any one of the squares that are deformed and deforms in response to an impact load,
When the cross-sectional shape of the cylindrical body is the circular shape, the average radius thereof, and when the cross-sectional shape is other than the circular shape, R represents a circular radius having the same circumference as the average length of the outer periphery thereof, and the thickness of the cylindrical body portion. T / R is 0.0150 or more, a / R is 0.036 or more, and λ /, where t is t, R is the wavelength of the waveform formed in the cylindrical body portion, and a is the amplitude of the waveform. When R is 0.2 or more and 0.89 or less and the cylindrical part is pressed from at least one end at a constant speed, the waveform excluding both ends is uniformly deformed, and the amount of instantaneous decrease in the load received by the cylindrical part The load absorbing member has a load fluctuation within 10% of the maximum load received before, and the load received by the cylinder body monotonously increases. The shock absorbing member according to claim 1, wherein the t / R, a / R, and λ / R satisfy the following relationship.
(1) When t / R is 0.0150 or more and 0.0179 or less, a / R: 0.054 or more, λ / R: 0.2 or more and 0.4 or less (2) t / R exceeds 0.0179 When 0.0357 or less, a / R: 0.036 or more, λ / R: 0.2 or more and 0.5 or less (3) When t / R is more than 0.0357 and 0.0537 or less, a / R: 0.036 or more, λ / R: 0.2 or more and 0.65 or less (4) When t / R is more than 0.0537 and 0.0714 or less, a / R: 0.036 or more, λ / R: 0. 2 or more and 0.89 or less (5) When t / R is more than 0.0714, a / R: 0.036 or more, λ / R: 0.2 or more and 0.89 or less 3. The impact absorbing member according to claim 1, wherein the cylindrical portion is a casting. 4. The impact absorbing member according to any one of claims 1 to 3, wherein a portion excluding both sides of the cylindrical portion is provided along one or both of an inner periphery and an outer periphery of the cylindrical portion. An impact absorbing member comprising: one or a plurality of reinforcing members capable of maintaining a cross-sectional shape of the cylindrical portion against deformation of the cylindrical portion.

Images