JP3782037B2 - Material strength evaluation method and material strength test apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a material strength evaluation method for evaluating the mechanical strength of a polymer material such as an ultraviolet curable resin, and a material strength test apparatus used for evaluating the mechanical strength of the polymer material.
[0002]
[Prior art]
In the technical field of optical fiber communication, an ultraviolet curable resin is used as a polymer material for a coating layer in an optical fiber.
[0003]
Here, the coating layer in the optical fiber generally has a double coating structure, is composed of a soft UV curable resin having a low Young's modulus, and directly covers the outer periphery of the glass fiber of the optical fiber. And a secondary coating layer that is made of a hard UV curable resin having a high Young's modulus and that indirectly coats the outer periphery of the glass fiber via the primary coating layer. . This is because when an external force is applied to the optical fiber, the deformation of the entire optical fiber is suppressed by the secondary coating layer, and further, the small deformation suppressed by the primary coating layer is absorbed, thereby the glass fiber. This is because the deformation due to the external force is not transmitted as much as possible.
[0004]
Further, in order to improve the quality of the optical fiber by minimizing transmission loss of the optical fiber due to minute bending of the glass fiber, the primary coating layer directly covers the glass fiber. Therefore, it is important to evaluate the mechanical strength of the soft ultraviolet curable resin constituting the primary coating layer rather than the mechanical strength of the hard ultraviolet curable resin constituting the secondary coating layer. . Therefore, a tensile test in which the test piece made of the soft ultraviolet curable resin is pulled in one direction is performed, and the breaking stress of the soft ultraviolet curable resin in a state where a tensile stress in one direction is applied is obtained.
[0005]
[Problems to be solved by the invention]
Meanwhile, the fiber glass and the secondary coating layer tend to shrink three-dimensionally as the resin temperature of the coating layer decreases from the time when the coating layer is cured to the end of the curing. 3-dimensional contraction of the primary coating layer because it is constrained becomes substantially uniformly applies that 3-dimensional tensile stresses in the primary coating layer by. Here, the time of completion of the curing, in addition to immediately after the completion of the curing, Ru der but also after the environmental temperature is changed from the end cured. Then, what the average tensile stress of the three-dimensional tensile stress acting on the primary coating layer exceeds a predetermined failure stress, said primary coating layer voids or cracks cause small bending of the glass fibers occurs It is.
[0006]
However, as described above, the tensile test of pulling the test piece made of the soft UV curable resin in one direction is performed, and the breaking stress of the soft UV curable resin in a state where a tensile stress in one direction is applied. only seek may be able to evaluate the mechanical strength of the ultraviolet curable resin of the soft in while applying a unidirectional tensile stress, ultraviolet said soft in while applying a three-dimensional tensile stress to the test piece The mechanical strength of the curable resin cannot be evaluated. Therefore, it is difficult to use the polymer material so that voids or cracks do not occur, such as using the soft ultraviolet curable resin so that voids or cracks do not occur in the primary coating layer in the optical fiber. Become.
[0007]
[Means for Solving the Problems]
In the invention according to claim 1, in the material strength evaluation method for evaluating the mechanical strength of the polymer material,
The surface of the thin disk-shaped test sheet made of the polymer material is fixed in close contact with the first constraining surface of the first fixing member, and the back surface of the test sheet is in close contact with the second constraining surface of the second fixing member. By restraining the stress effective region excluding the vicinity of the outer peripheral portion of the entire region of the test sheet so as not to be displaced in the radial direction and the circumferential direction,
While observing the test sheet from the outside of any one of the fixing members configured to be transparent, the first fixing member is tested in the state in which the first and second restraining surfaces are held in parallel. by relatively small displacement a thickness direction of the sheet to the separating direction of separating from the second fixing member, a substantially uniform three-dimensional tensile stress in said stress effective area of the test sheet was added,
And wherein determining the failure stress of the polymer material in the state based on the relative displacement of said first fixing member, was added 3-dimensional tensile stress at the time when voids or cracks occurred in the test sheet To do.
[0008]
Here, the three-dimensional tensile stress refers to a three-dimensional to the applied tensile stress in the thickness direction and the radial direction to the stresses effective area, the height at a stress state that joined the three-dimensional tensile stress The failure stress of the molecular material means an average tensile stress of a three-dimensional tensile stress that acts on the stress effective region of the test sheet when a void or a crack occurs in the test sheet. Further, the term “transparent” includes translucent and colored transparency in addition to completely transparent.
[0009]
The invention described in claim 2 is characterized in that, in addition to the matters specifying the invention described in claim 1, the polymer material is an ultraviolet curable resin.
[0010]
In the invention according to claim 3, in addition to the matters specifying the invention according to claim 1, the polymer material is the same ultraviolet curable resin as the primary coating layer in the optical fiber,
The thickness of the test sheet is the same as the thickness of the primary coating layer in the optical fiber.
[0011]
In the invention according to claim 4, in the material strength test apparatus used for evaluating the mechanical strength of the polymer material,
A first fixing member having a first constraining surface to which the surface of the thin disk-shaped test sheet made of the polymer material is closely attached and fixed;
A second fixing member facing the first fixing member and having a second restraining surface to which the back surface of the test sheet is fixed in close contact;
With the first constraining surface and the second constraining surface being held in parallel, the first fixing member is relative to the separation direction that is away from the second fixing member in the thickness direction of the polymer material. And a micro displacement mechanism that makes micro displacement
At least one of the first fixing member and the second fixing member is configured to be transparent.
[0012]
Here, the term “transparent” includes not only completely transparent but also translucent and colored transparent.
[0013]
According to the invention specific matter of claim 4, the surface of the test sheet is fixed in close contact with the first restraining surface of the first fixing member, and the back surface of the test sheet is fixed to the second fixing member. Closely fixed to the second restraining surface. Thereby, the stress effective area | region except the outer peripheral part vicinity can be restrained so that it may not displace to radial direction and the circumferential direction among all the areas | regions of the said test sheet.
[0014]
Then, while observing the test sheet from the outside of any one of the fixing members, the first displacement surface and the second constraint surface are held in parallel and the first displacement surface is operated by the micro displacement mechanism. The fixing member is slightly displaced relative to the second fixing member in the separating direction. As a result, the test sheet tends to shrink three-dimensionally, but the displacement in the radial and circumferential directions of the stress effective region of the test sheet is constrained by the first constraining surface and the second constraining surface. since, in addition to the thickness direction of the tensile stress to the stress the effective area of the test sheet, can be added to the radial tensile stress, in other words, three-dimensional tensile the stress effective area of the test sheet stress can be added, also, since the thickness of the test sheet is thin, can be added substantially uniformly three-dimensional tensile stress in said stress effective area of the test sheet.
[0015]
Here, the three-dimensional tensile stress refers to a tensile stress that is three-dimensionally applied to the effective stress region in the radial direction and the thickness direction .
[0016]
Furthermore, I'll be relative small displacement amount of the first fixing member is increased, the stress the effective region 3 dimensional tensile stress gradually increased in the test sheet, voids or cracks in the said test sheet . Then, based on the relative displacement of said first fixing member at the time when the test sheet to voids or cracks occur, seek failure stress of the polymeric material in the state plus the three-dimensional tensile stress. This makes it possible to evaluate the mechanical strength of the polymer material in a state of plus three dimensional tensile stress.
[0017]
Here, the polymeric material in a state of plus three dimensional tensile stress The failure stress, the voids or cracks in the test sheets is three-dimensional tensile stress acting on the stress effective area of the test sheet when it occurs The average tensile stress.
[0018]
The invention according to claim 5 is characterized in that, in addition to the matters specifying the invention according to claim 4, each of the first fixing member and the second fixing member is made of glass.
[0019]
According to the invention specific matter of the fifth aspect, in addition to the invention specific matter of the fourth aspect, since the first fixing member and the second fixing member are made of glass, respectively, the first constraint The fixed state in which the test sheet is in close contact with the surface and the second constraining surface is stabilized.
[0020]
In the invention according to claim 6, in addition to the matters specifying the invention according to claim 4 or claim 5, an enlargement for observing the test sheet from the outside of any one of the fixing members It is characterized by comprising a mirror.
[0021]
According to the invention specific matter of claim 6, in addition to the action of the invention specific matter of claim 4 or 5, the test sheet can be magnified and observed by the magnifier.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a schematic perspective view of a material strength test apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining a material strength evaluation method according to an embodiment of the present invention. FIG. 3 is a top view of the test sheet in FIG.
[0024]
Here, “up” refers to the top in FIG. 1 and FIG. 2 and the table toward the paper surface in FIG. 3, and “lower” refers to the bottom in FIG. 1 and FIG. 2, and back to the paper surface in FIG. I mean.
[0025]
As shown in FIG. 1, a material strength test apparatus 1 according to an embodiment of the present invention is an apparatus used for evaluating the mechanical strength of a soft ultraviolet curable resin (one of polymer materials). The rectangular first holder 3 and the rectangular second holder 5 are provided so as to face each other vertically.
[0026]
In order to support the first holder 3 so as to be movable in the vertical direction with respect to the second holder 5, the second holder 5 is provided with a plurality of fixing protrusions 7. Guide pins 9 are erected, and the first holder 3 is provided with a plurality of movable protrusions 11 that are guided by the corresponding guide pins 9 so as to be movable in the vertical direction.
[0027]
A circular first fixing member 13 is provided at the center of the first holder 3, and the surface of the very thin disk-shaped test sheet S is fixed in close contact by an adhesive action. The first constraining surface 13f (see FIG. 2). In addition, a circular second fixing member 15 is provided at the center of the second holder 5 so as to face the first fixing member 13 in the vertical direction, and the back surface of the test sheet S is bonded to the second fixing member 15. It has the 2nd constraining surface 15f (refer FIG. 2) fixed closely by an effect | action.
[0028]
Here, the first fixing member 13 and the second fixing member 15 are each made of transparent glass. The transparent glass includes translucent glass and colored transparent glass in addition to completely transparent glass. Further, instead of configuring the first fixing member and the second fixing member to be transparent, any one of the first fixing member 13 and the second fixing member 15 may be configured to be transparent.
[0029]
The test sheet S is made of the same soft ultraviolet curable resin (an example of a polymer material) as the soft ultraviolet curable resin constituting the primary coating layer in an optical fiber (not shown). The thickness of is the same as the thickness of the primary coating layer in the optical fiber. In addition, the fixing method of the test sheet S is not limited to the above-described adhesive action, and for example, a fluid UV curable resin is filled between the first fixing member 13 and the second fixing member 15 so as to be fluid. The ultraviolet curable resin may be fixed by curing with ultraviolet irradiation.
[0030]
A mounting protrusion 17 is provided on the first holder 3, and a contact protrusion 19 is provided on the second holder 5 so as to face the mounting protrusion 17 in the vertical direction. In order to slightly displace the first fixing member 13 in the upward direction (in other words, in the direction of the thickness of the test sheet S and away from the second fixing member 15), the mounting protrusion 17 rotates the knob 21. A micrometer head 25 having a spindle 23 that can be slightly expanded and contracted in the vertical direction by an operation is provided, and a tip end portion (lower end portion) of the spindle 23 can be brought into contact with a contact protrusion.
[0031]
Therefore, the first fixing member 13 is integrated with the first holder 3 by bringing the tip of the spindle 23 into contact with the contact protrusion 19 and extending the spindle 23 by a small amount by rotating the knob 21. Can be slightly displaced upward.
At this time, since the plurality of movable protrusions 11 are guided by the plurality of guide pins 9 and displaced upward, the first constraining surface 13f and the second constraining surface 15f are held in parallel.
[0032]
The mechanism for minutely displacing the first fixing member 13 is not limited to the micrometer head 25, and an appropriate minute displacement mechanism can be used. Further, instead of causing the first fixing member 13 to be slightly displaced upward, the second fixing member 15 may be slightly displaced downward, or the first fixing member 13 and the second fixing member 15 may be separated from each other. You may make it carry out a minute displacement to a direction.
[0033]
Above the first holder 3, a microscope 27 for observing the test sheet S from the upper outside of the first fixing member 13 is provided via a support arm (not shown). The microscope 27 can change its posture, position, etc. through an appropriate mechanism.
[0034]
Next, the material strength evaluation method according to the embodiment of the present invention will be described including its operation.
[0035]
As shown in FIG. 2, the surface of the test sheet S is fixed in close contact with the first restraining surface 13 f of the first fixing member 13 by an adhesive action, and the back surface of the test sheet S is fixed to the second restraining surface of the second fixing member 15. The surface 15f is adhered and fixed by an adhesive action (see FIG. 2A). Thereby, the stress effective area | region Sa except the outer peripheral part vicinity can be restrained so that it may not displace to radial direction and the circumferential direction among the all areas | domains of the test sheet S. In addition, since the 1st fixing member 13 and the 2nd fixing member 15 are each comprised with glass, the fixed state which the test sheet S contact | adhered with respect to the 1st restraint surface 13f and the 2nd restraint surface 15f is stabilized.
[0036]
Here, when the stress effective region Sa is made clearer, in the embodiment of the present invention, when the first fixing member 13 is slightly displaced upward, an R-shaped dent Sd is formed on the outer peripheral surface of the test sheet S. However, the stress effective area Sa is an area excluding the vicinity of the outer peripheral portion of the entire area of the test sheet S, and means an area where the dent Sd does not occur.
[0037]
Then, while magnifying and observing the test sheet S from the outside of the first fixing member 13 with the microscope 27, the tip portion of the spindle 23 is held in a state where the first restraining surface 13f and the second restraining surface 15f are held in parallel. Is brought into contact with the contact protrusion 19, and the knob 21 is rotated to slightly displace the spindle 23 downward, and the first fixing member 13 is slightly displaced upward (see FIG. 2B). As a result, the test sheet S tends to shrink three-dimensionally, but the radial and circumferential displacements of the stress effective region Sa of the test sheet S are constrained by the first constraining surface 13f and the second constraining surface 15f. since, in addition to the tensile stress σz of the thickness direction stress effective area Sa of the test sheets S (vertical direction in FIG. 2), it said radial tensile stress sigma r can impart, in other words, the test 3-dimensional tensile stress to the stress the effective area Sa of the sheet S (σ r, σ z) can impart. Further, since it is extremely thin thickness of the test sheet S, it is possible to state that adding a substantially uniform three-dimensional tensile stress stress effective area Sa of the test sheets S.
[0038]
Furthermore, by the minute displacement of the first fixing member 13 is increased, becomes gradually higher three-dimensional tensile stress of stress effective area Sa of the test sheet S, the voids V or crack test sheets S (not shown) Occurs (see FIG. 2 (c)). Then, based on the displacement amount of the first fixing member 13 at the time when the void V or cracked in the test sheet S, determining the failure stress of the ultraviolet curable resin of the soft in while applying a three-dimensional tensile stress. This makes it possible to evaluate the mechanical strength of the three-dimensional tension the soft in a state in which stressed the ultraviolet curable resin (an example of a polymeric material).
[0039]
Here, three-dimensional tensile stress with respect to the displacement amount of the first fixing member 13 may be determined using an analysis such as the finite element method, the displacement amount of the first fixing member 13 in the stress effective area Sa of the test sheets S linear relationship of between the and 3-dimensional tensile stress. Further, the failure stress of the ultraviolet curable resin of the soft in while applying a three-dimensional tensile stress, a three-dimensional acting stress effective area Sa of the test sheet S when the void V or cracked in the test sheet S It means the average tensile stress.
[0040]
According to the above-described, embodiments of the present invention, ultraviolet in a state where seeking failure stress of the ultraviolet curable resin of the soft in while applying a three-dimensional anisotropic tensile stress, was added 3-dimensional tensile stress Since the mechanical strength of the curable resin can be evaluated, the soft ultraviolet curable resin can be easily used so that the void V or crack does not occur in the primary coating layer of the optical fiber, and the soft ultraviolet The curable resin can be effectively used in various fields.
[0041]
Further, the test sheet S is made of the same soft ultraviolet curable resin as the soft ultraviolet curable resin constituting the primary coating layer in the optical fiber, and the thickness of the test sheet S in the optical fiber is the same as that in the optical fiber. Since the thickness is the same as the thickness of the primary coating layer, the test sheet S can be in substantially the same state as the primary coating layer in the optical fiber, and the soft UV curing that constitutes the primary coating layer in the optical fiber. The mechanical strength of the mold resin can be accurately evaluated.
[0042]
Furthermore, since the fixed state in which the test sheet S is in close contact with the first constraining surface 13f and the second constraining surface 15f is stabilized, the three-dimensional tensile stress (σ r , σ z ) is further increased in the stress effective region Sa of the test sheet S. are equalized, the mechanical strength of the ultraviolet curable resin of the soft in while applying a three-dimensional tensile stress can be accurately evaluated.
[0043]
Further, since it observe an enlarged test sheets S by microscopic 27, test sheets voids V or cracks occurring in S can easily find, in the ultraviolet curable resin of the soft in 3-dimensional tensile stress state corruption Stress can be determined accurately.
[0044]
The present invention is not limited to the description of the embodiment of the invention described above. For example, the test sheet is made of another polymer material other than the ultraviolet curable resin, so that Appropriate changes can be made, such as evaluating the mechanical strength of the material.
[0045]
【Example】
Embodiments according to the present invention will be briefly described below.
[0046]
The outer diameter and the outer diameter of the second fixing member 15 and 100mm, Young's modulus 1 MPa, thickness 100 [mu] m, substantially uniformly three-dimensional tensile stress in the stress effective area Sa of the test sheet S outside diameter 100mm of the first fixing member 13 ( σ r , σ z ) .
[0047]
Here, in advance, by analysis by the finite element method, it is required from the center of the radius 45mm area of the test sheet S is stress effective area Sa that acts substantially uniform three-dimensional tensile stress, further, the first fixing member When 13 is slightly displaced to 50 μm in 5 μm steps, the relationship between the three-dimensional tensile stress acting on the stress effective region Sa of the test sheet S and the displacement amount of the first fixing member 13 is the displacement of the first fixing member 13. 3-dimensional tensile stress in an amount 50 [mu] m (sigma r is 1.9 MPa, sigma z is 2.3 MPa) are linear relationship is determined such that.
[0048]
Under the condition, as described above, the first fixing member 13 is finely displaced upward, substantially uniformly three-dimensional tensile stress (σr, σz) in stress effective region Sa test sheets S Addition of void V is generated in the stress effective area Sa of the test sheet S when the displacement amount 30μm of the first fixing member 13, three-dimensional tensile stress (sigma r acting on stress effective area Sa of the test sheet S at this time is 1 The average tensile stress of 1.2 MPa ( .1 MPa , σ z is 1.4 MPa) can be used as the failure stress of the soft UV-curable resin.
[0049]
【The invention's effect】
According to claim 1, the invention according to any of claims one of claims 6, seeking failure stress of the polymeric material in the state plus the three-dimensional tensile stress, a 3-order tensile stress Since the mechanical strength of the polymer material in an added state can be evaluated, the polymer material can be easily used so that voids or cracks do not occur, and the polymer material can be effectively used in various fields. be able to.
[0050]
According to a third aspect of the present invention, the polymer material is the same soft ultraviolet curable resin as the primary coating layer in the optical fiber, and the thickness of the test sheet is set to the primary coating layer in the optical fiber. Therefore, the test sheet can be brought into substantially the same state as the primary coating layer in the optical fiber, and the soft ultraviolet curable resin constituting the primary coating layer in the optical fiber can be formed. The mechanical strength can be accurately evaluated.
[0051]
In the invention described in claim 5, since the fixing state of close contact of the test sheet relative to the first constraining surface and said second constraining surface is stabilized, 3-dimensional tensile in the stress effective area of the test sheet stress is more uniform, it is possible to accurately evaluate the mechanical strength of the polymer material in a state of plus three dimensional tensile stress.
[0052]
In the invention described in claim 6, since the observable expanding the test sheets by the magnifying glass, can find a void or crack generated in the test sheet easily, the 3-dimensional tensile stress The breaking stress of the polymer material in the added state can be accurately obtained.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a material strength test apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a material strength evaluation method according to an embodiment of the present invention.
3 is a top view of the test sheet in FIG. 2 (b).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Material strength test apparatus 13 1st fixing member 13f 1st restraint surface 15 2nd fixing member 15f 2nd restraint surface 23 Spindle 25 Micrometer head 27 Microscope

Claims (6)

In a material strength evaluation method for evaluating the mechanical strength of a polymer material,
The surface of the thin disk-shaped test sheet made of the polymer material is fixed in close contact with the first constraining surface of the first fixing member, and the back surface of the test sheet is in close contact with the second constraining surface of the second fixing member. By restraining the stress effective region excluding the vicinity of the outer peripheral portion of the entire region of the test sheet so as not to be displaced in the radial direction and the circumferential direction,
While observing the test sheet from the outside of any one of the fixing members configured to be transparent, the first fixing member is tested in the state in which the first and second restraining surfaces are held in parallel. by relatively small displacement a thickness direction of the sheet to the separating direction of separating from the second fixing member, a substantially uniform three-dimensional tensile stress in said stress effective area of the test sheet was added,
And wherein determining the failure stress of the polymer material in the state based on the relative displacement of said first fixing member, was added 3-dimensional tensile stress at the time when voids or cracks occurred in the test sheet Material strength evaluation method.   The material strength evaluation method according to claim 1, wherein the polymer material is an ultraviolet curable resin. The polymer material is the same ultraviolet curable resin as the primary coating layer in the optical fiber,
The material strength evaluation method according to claim 1, wherein the thickness of the test sheet is the same as the thickness of the primary coating layer in the optical fiber. In a material strength test apparatus used to evaluate the mechanical strength of a polymer material,
A first fixing member having a first constraining surface to which the surface of the thin disk-shaped test sheet made of the polymer material is closely attached and fixed;
A second fixing member facing the first fixing member and having a second restraining surface to which the back surface of the test sheet is fixed in close contact;
Under the state where the first restraining surface and the second restraining surface are held in parallel, the first fixing member is moved away from the second fixing member in the thickness direction of the polymer material. A relatively small displacement mechanism for relatively small displacement,
A material strength test apparatus, wherein at least one of the first fixing member and the second fixing member is transparent.   The material strength test apparatus according to claim 4, wherein the first fixing member and the second fixing member are made of glass.   6. The material strength test apparatus according to claim 4, further comprising a magnifying mirror for magnifying and observing the test sheet from the outside of any one of the fixing members.

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