Patent Description:
Various applications use vibration testing for components that will be subject to vibrations during normal operation. For example, hardware, circuit card assemblies including stacks of circuit cards, and other subsystem level units may be subject to random vibrations, harmonic vibrations, and controlled shock profiles when implemented in a particular environment. Exemplary environments in which the components may be subject to vibrations include moving platforms such as aircrafts, missiles, spacecrafts or satellites, sea vessels, land vehicles, etc..

Vibration testing may include automated coupling and decoupling of components with a vibration testing unit utilizing a conventional coupler which includes an upper coupler part and a lower coupler part. After the vibration testing, the parts are disengaged and decoupled from the vibration testing unit, but the environment imparted on the parts during the decoupling may not be benign. The pressure applied to decouple the upper and lower coupler parts may cause the upper coupler part to rapidly accelerate upwardly and then downwardly relative to the lower coupler part such that the upper coupler part hits the lower coupler part and causes a significant shock. Conventional couplers may not be sufficient in preventing shock transfer between the upper and lower coupler parts during decoupling, such that the shock occurring during decoupling may exceed the shock specifications for the particular component that is subject to the vibration testing. Consequently, the test component may be damaged by the excess shock.

<CIT> discloses an electrodynamic actuator comprising a table, a support mounting said table for approximately horizontal linear movements, means responsive to a variable current for causing said movements of said table, and means for providing a variable damping for said table including a magnet attached to and movable with said table and having its polar ends spaced apart in the direction of said linear movements, and a closed circuit having in series therein a variable resistance and a wire coil carried by said support and wound about but separate from said magnet intermediate of the ends thereof, whereby the movement of said magnet relative to said coil will exert a damping force the effectiveness of which may be varied by operation of said variable resistance.

<CIT> discloses that two or more vehicle components can be operatively connected with one or more fasteners configured to provide selectively variable dampening characteristics. The fastener can include a dampening unit configured to provide different dampening characteristics based on a torque applied to the fastener. In one or more arrangements, the dampening unit can provide different dampening characteristics based on an amount of compression the dampening unit is under. Target dampening characteristics between two or more components can be determined. A torque can be determined and applied to the fastener based on the target dampening characteristics. The torque can cause the dampening unit of the fastener to compress and provide the target dampening characteristics between the components.

<CIT> discloses a test apparatus including a vibratory body that shakes a device under testing (DUT), a pedestal dedicated to support the DUT and disposed on the vibratory body, and a clamping mechanism operative to selectively clamp the pedestal to the vibratory body and release the pedestal from the vibratory body. The vibratory body and the pedestal define a cavity in which the clamping mechanism is disposed. The clamping mechanism includes a clamp ring and at least one locking element carried by the clamp ring so as to be displaceable in a radial direction relative to the clamp ring, at least one tang facing the at least one locking element in the radial direction, and a piston slidable in an axial direction relative to the clamp ring between a first position at which the pedestal is free from vibratory body and a second position at which the locking element is compressed between the piston and the tang.

<CIT> discloses a structure to provide increased surface area on the head of a shaker used for vibrational testing. The structure includes a base plate for attachment to the head of the shaker and a larger expanded head connected thereto by a frustoconical structure surrounding a cylindrical structure surrounding a spoke structure, all designed to increase the vibrational frequency at which undesired vibratory modes appear in the surface of the expanded head which otherwise can provide nonuniform vibration loading to the items attached thereto during testing. The structure also includes improved means for attachment to the shaker.

In an aspect, the disclosure provides a shock isolator arranged between automated coupler parts in a vibration testing unit, the shock isolator comprising: a bushing; and a compressive fit rod supported in the bushing, the compressive fit rod being compressible inside the bushing to disable the shock isolator when the automated coupler parts are engaged during vibration testing, the compressive fit rod being expandable outwardly from the bushing to activate the shock isolator and absorb excess shock energy when the automated coupler parts are disengaged.

According to another aspect, the disclosure provides a vibration testing unit comprising: an automated coupler having an upper coupler part and a lower coupler part that are engaged during vibration testing and disengaged after the vibration testing; and a plurality of shock isolators arranged in the lower coupler part between the upper coupler part and the lower coupler part, each of the plurality of shock isolators including a bushing and a compressive fit rod supported in the bushing, the compressive fit rod being compressible to a compressed position in which the compressive fit rod is compressed inside the bushing to disable the plurality of shock isolators when the upper coupler part and the lower coupler part are engaged during vibration testing, the compressive fit rod being expandable to an expanded position in which the compressive fit rod expands outwardly from the bushing to activate the plurality of shock isolators and absorb excess shock energy when the upper coupler part and the lower coupler part are disengaged.

According to another aspect, the disclosure provides a method of vibration testing, the method comprising: press-fitting a compressive fit rod into a bushing to form a shock isolator; inserting one or more shock isolators into a lower coupler part of two automated coupler parts between the lower coupler part and an upper coupler part of the two automated coupler parts; engaging the two automated coupler parts during vibration testing and disengaging the two automated coupler parts after the vibration testing; compressing an upper portion of the compressive fit rod inside the bushing to disable the one or more shock isolators during the vibration testing; and expanding the upper portion of the compressive fit rod upwardly from and outside the bushing to activate the one or more shock isolators and absorb excess shock energy when the two automated coupler parts are disengaged.

The present application provides shock isolation for a vibration testing unit that includes an automated coupler. The shock isolator is arranged between two automated coupler parts. When the coupler parts are engaged and coupled during vibration testing of a component, the shock isolator is disabled due to compression. When the coupler parts are disengaged and decoupled after vibration testing, the shock isolator is expanded and can absorb excess shock energy and prevent shock transfer between the coupler parts that may damage the test component.

Each shock isolator includes a bushing that is inserted in the lower coupler part and a compressive fit rod that is press-fit into the bushing. The compressive fit rod is formed of an elastomeric material that is able to be repeatedly compressed and expanded without permanent deformation. The bushing has a chamfered volume and the compressive fit rod has a corresponding compressible volume that is displaced into the chamfered volume to disable the shock isolator when the coupler parts are engaged. After vibration testing, the coupler parts are disengaged and the compressive fit rod expands to its decompressed shape to activate the shock isolator and absorb the excess shock energy.

Incorporating the shock isolator into an automated coupler is advantageous in that the shock isolator does not change the overall vibration performance of the test environment when the compressive fit rod is compressed inside the bushing. The shock isolator is effectively shorted out when the coupler parts are engaged during vibration testing. The compressive fit rod has a predetermined durometer and a lower portion of the compressive fit rod is press-fit into the bushing. The upper portion of the compressive fit rod is a compressive volume that is deformed during coupling. An axial length of the compressible volume may be less than ten percent of the total axial length of the compressive fit rod which enables the compression profile of the compressive fit rod to be linear.

According to an aspect of the disclosure, an automated coupler may include one or more shock isolators arranged between the two coupler parts.

According to an aspect of the disclosure, an automated coupler may include a shock isolator that is disabled during coupling of the two automated coupler parts and activated when the two automated coupler parts are decoupled to absorb excess shock energy.

According to an aspect of the disclosure, a shock isolator may include a bushing and a compressive fit rod inserted in the bushing.

According to an aspect of the disclosure, a shock isolator may include a bushing and a compressive fit rod that is deformable inside the bushing to disable the shock isolator when two automated coupler parts are coupled during vibration testing.

According to an aspect of the disclosure, a shock isolator may include a bushing having a chamfered volume and a compressive fit rod having a corresponding compressible volume that fits inside the chamfered volume.

According to an aspect of the disclosure, a shock isolator may include a bushing and a compressive fit rod having a compressible volume that is the only portion of the compressive fit rod deformable inside the bushing.

According to an aspect of the disclosure, a shock isolator is arranged between coupler parts in an automated coupler and includes a bushing, and a compressive fit rod supported in the bushing, the compressive fit rod being compressible inside the bushing to disable the shock isolator when the coupler parts are coupled during vibration testing, the compressive fit rod being expandable outwardly from the bushing to activate the shock isolator and absorb excess shock energy when the coupler parts are decoupled.

According to an embodiment of any paragraph(s) of this summary, the bushing may define a chamfered volume and the compressive fit rod may have a compressible volume that is equivalent to the chamfered volume, wherein the chamfered volume is filled by the compressive fit rod when the compressive fit rod is deformed during compression.

According to an embodiment of any paragraph(s) of this summary, the chamfered volume may be defined by a tapered surface that tapers radially inwardly from a radial mating surface of the bushing.

According to an embodiment of any paragraph(s) of this summary, the radial mating surface may be an upper surface of the bushing that engages an upper coupler part of the coupler parts.

According to an embodiment of any paragraph(s) of this summary, the tapered surface may extend an axial distance that is less than half of an entire axial length of the bushing.

According to an embodiment of any paragraph(s) of this summary, the tapered surface may be angled by between ten and <NUM> degrees relative to a longitudinal axis of the shock isolator.

According to an embodiment of any paragraph(s) of this summary, the compressive fit rod may have a compressible volume that is deformed during compression and has an axial length that is ten percent or less of a total axial length of the compressive fit rod.

According to an embodiment of any paragraph(s) of this summary, the compressible volume may be an uppermost portion of the compressive fit rod.

According to an embodiment of any paragraph(s) of this summary, the compressive fit rod may be press-fit into the bushing.

According to an embodiment of any paragraph(s) of this summary, the compressive fit rod may have a compressive fit with the bushing that is ten percent or less.

According to an embodiment of any paragraph(s) of this summary, the compressive fit rod may define an axially-extending through-aperture.

According to an embodiment of any paragraph(s) of this summary, the bushing may define a radial seat against which an axial end of the compressive fit rod is supported.

According to an embodiment of any paragraph(s) of this summary, the compressive fit rod may be formed of an elastomeric material having a durometer between <NUM> and <NUM>.

According to an embodiment of any paragraph(s) of this summary, the compressive fit rod may be formed of a urethane material.

According to an embodiment of any paragraph(s) of this summary, the bushing may be formed of a thermoplastic polymer material.

According to an embodiment of any paragraph(s) of this summary, an upper portion of the compressive fit rod may be compressed inside an upper portion of the bushing when in a compressed position, and wherein the upper portion expands upwardly and outside of the bushing to an expanded position which corresponds to a decompressed or normal shape of the compressive fit rod.

According to another aspect of the disclosure, a vibration testing unit includes an upper coupler part and a lower coupler part that are coupled during vibration testing and decoupled after the vibration testing, and a plurality of shock isolators arranged in the lower coupler part between the upper coupler part and the lower coupler part, each of the plurality of shock isolators including a bushing and a compressive fit rod supported in the bushing, the compressive fit rod being compressible to a compressed position in which the compressive fit rod is compressed inside the bushing to disable the plurality of shock isolators when the upper coupler part and the lower coupler part are coupled during vibration testing, the compressive fit rod being expandable to an expanded position in which the compressive fit rod expands outwardly from the bushing to activate the plurality of shock isolators and prevent shock transfer when the upper coupler part and the lower coupler part are decoupled.

According to still another aspect of the disclosure, a method of vibration testing includes press-fitting a compressive fit rod into a bushing to form a shock isolator, inserting one or more shock isolators into a lower coupler part of two automated coupler parts between the lower coupler part and an upper coupler part of the two automated coupler parts, coupling the two automated coupler parts during vibration testing and decoupling the two automated coupler parts after the vibration testing, compressing an upper portion of the compressive fit rod inside the bushing to disable the one or more shock isolators during the vibration testing, and expanding the upper portion of the compressive fit rod upwardly from and outside the bushing to activate the one or more shock isolators and prevent shock transfer when the two automated coupler parts are decoupled.

According to an embodiment of any paragraph(s) of this summary, compressing the upper portion of the compressive fit rod may include filling a chamfered volume formed in an upper portion of the bushing and expanding the upper portion of the compressive fit rod includes removing the compressive fit rod from the chamfered volume.

According to an embodiment of any paragraph(s) of this summary, compressing the upper portion of the compressive fit rod may include compressing a compressible volume of the compressive fit rod that has an axial length of the compressive fit rod that is ten percent or less of a total axial length of the compressive fit rod.

To the accomplishment of the foregoing and related ends, the disclosure comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the disclosure. These embodiments are indicative, however, of but a few of the various ways in which the principles of the disclosure may be employed. Other objects, advantages and novel features of the disclosure will become apparent from the following detailed description when considered in conjunction with the drawings.

The annexed drawings, which are not necessarily to scale, show various aspects of the disclosure.

The principles described herein have application in vibration testing units and methods of vibration testing. A vibration testing unit includes two automated coupler parts that are engaged together and coupled during vibration testing of a component and decoupled after the vibration testing. Vibration testing may occur in an enclosed automated system in which there is no manual operation or human interaction. The vibration testing unit described herein may be used for any suitable component that is subject to vibration during normal operation. When implemented in a moving platform during normal operation, such as an aircraft, missile, spacecraft or satellite, sea vessel, land vehicle, etc., the component may be subject to random vibrations, harmonic vibrations, or controlled shock profiles depending on the environment. Exemplary components that may undergo vibration testing prior to operation include hardware components, circuit card assemblies, stacks of circuit cards, and other subsystem level units.

Referring first to <FIG> and <FIG>, a vibration testing unit <NUM> for any suitable component is shown. The vibration testing unit <NUM> includes two automated coupler parts <NUM>, <NUM> having an upper coupler part <NUM> and a lower coupler part <NUM> that are engageable with each other. <FIG> shows a top view of the lower coupler part <NUM> with the upper coupler part <NUM> removed. An interior area <NUM> is arranged along a central axis A of the vibration testing unit <NUM> within the vibration testing unit <NUM>. The interior area <NUM> is enclosed between the two automated coupler parts <NUM>, <NUM> when the vibration testing unit <NUM> is assembled. A component <NUM> is received and supported in the interior area <NUM> for automated vibration testing performed by the vibration testing unit <NUM>. The interior area <NUM> may be shaped and sized to accommodate any suitable component. Any suitable fasteners <NUM> or other support mechanisms <NUM> may be used to support and accommodate the component <NUM>. The vibration testing unit <NUM> may have many different configurations depending on the component or components to be tested.

During vibration testing of the component <NUM>, the upper coupler part <NUM> and the lower coupler part <NUM> are engaged and coupled together. After the vibration testing, the upper coupler part <NUM> and the lower coupler part <NUM> are disengaged and decoupled using a suitable pneumatic device that exerts a positive pressure on the vibration testing unit <NUM>. One or both of the automated coupler parts <NUM>, <NUM> may be movable towards and away from each other for coupling and decoupling, respectively. The automated coupler parts <NUM>, <NUM> may be movable in an axial direction along the central axis A of the vibration testing unit <NUM>. In exemplary embodiments, the lower coupler part <NUM> may always remain stationary and the upper coupler part <NUM> may move downwardly toward the lower coupler part <NUM> for coupling during vibration testing and upwardly away from the lower coupler part <NUM> to disengage the lower coupler part <NUM> for decoupling. The coupling and decoupling operation may be automated in that the movement of the automated coupler parts <NUM>, <NUM> may be preset or automated.

The vibration testing unit <NUM> includes one or more shock isolators <NUM> that are arranged between the upper coupler part <NUM> and the lower coupler part <NUM>. The lower coupler part <NUM> may be formed to have one or more apertures <NUM> configured to receive a corresponding one of the shock isolators <NUM>. The apertures <NUM> are sized and shaped to correspond to the size and shape of the shock isolators <NUM> so that the shock isolators <NUM> are matingly engageable within the apertures <NUM>. Each of the apertures <NUM> may be formed to have a radial surface that defines a seat <NUM> configured to engage with and support the shock isolator <NUM> when the shock isolator <NUM> is inserted into the lower coupler part <NUM>.

Any number of shock isolators <NUM> may be provided and the shock isolators <NUM> may be uniform in terms of size and shape. The number of shock isolators <NUM> may be selected depending on the amount of mating surface area between the shock isolators <NUM> and the upper coupler part <NUM> which is assembled over the shock isolators <NUM> when inserted into the apertures <NUM> of the lower coupler part <NUM>. For example, the number of shock isolators <NUM> may be increased if the amount of mating surface area is increased. The number of shock isolators <NUM> may also be selected depending on the amount of pressure applied during decoupling to ensure that the shock isolators <NUM> are able to activate. Between six and ten shock isolators <NUM> may be suitable. Eight shock isolators <NUM> may be used in the exemplary embodiment shown in <FIG>. Fewer than six and more than ten shock isolators <NUM> may also be suitable in other exemplary applications.

As shown in <FIG>, the shock isolators <NUM> may be disposed circumferentially around the lower coupler part <NUM>. The shock isolators <NUM> may be arranged in any suitable pattern. In an exemplary arrangement, the shock isolators <NUM> may be arranged in an ordered pattern in which the shock isolators <NUM> are uniformly spaced and have a same radial distance to a center of the vibration testing unit <NUM>. Although the vibration testing unit <NUM> is shown as being cylindrical in shape, the shock isolators <NUM> may be implemented in a vibration testing unit with coupler parts having any other shape. Accordingly, the pattern of the shock isolators <NUM> may vary depending on the size and shape of the vibration testing unit and the automated coupler parts <NUM>, <NUM>.

Referring in addition to <FIG> and <FIG>, details of the shock isolator <NUM> are shown. The shock isolator <NUM> includes a bushing <NUM> and a compressive fit rod <NUM> that is inserted to be arranged in the bushing <NUM>. The bushing <NUM> has a main body <NUM> and a flange <NUM> that is integrally formed with the main body <NUM>. The flange <NUM> may be disc-shaped and extends radially outwardly relative to the main body <NUM>. The main body <NUM> may have a longer axial length than the flange <NUM>. The main body <NUM> may be cylindrical in shape and has an outer surface <NUM> that defines a smaller relative to the diameter of an outer surface <NUM> of the flange <NUM>. When assembled in the vibration testing unit <NUM>, the flange <NUM> defines a radially-extending upper surface <NUM> of the bushing <NUM>. The upper surface <NUM> forms a radial mating surface that is matingly engageable with the upper coupler part <NUM>, as shown in <FIG>. A lower surface <NUM> of the flange <NUM> that opposes the upper surface <NUM> matingly engages with the seat <NUM> formed in the lower coupler part <NUM> such that the shock isolator <NUM> is interposed between the upper coupler part <NUM> and the lower coupler part <NUM>.

The main body <NUM> has an inner radial surface <NUM> that extends radially inwardly and forms a radial seat for a corresponding axial end of the compressive fit rod <NUM>. The inner radial surface <NUM> is formed proximate a lower axial end <NUM> of the shock isolator <NUM> that is distally opposite the upper surface <NUM> of the flange <NUM> of the bushing <NUM>. The compressive fit rod <NUM> is received in an axial bore <NUM> of the bushing <NUM>. The axial bore <NUM> may be a through-bore that extends through an entire axial length of the bushing <NUM>. The through-bore has a non-uniform diameter along a longitudinal axis L of the shock isolator <NUM>. The longitudinal axis L of each shock isolator <NUM> may be parallel with the central axis A of the vibration testing unit <NUM> (shown in <FIG>). The compressive fit rod <NUM> is concentrically arranged with the bushing <NUM> such that the compressive fit rod <NUM> and the bushing <NUM> share the common longitudinal axis L. The compressive fit rod <NUM> may be formed to have any suitable shape. As shown in <FIG>, a cylindrical shape is a suitable shape, but other shapes may also be suitable for other applications.

The compressive fit rod <NUM> is press-fit (interference fit) into the bushing <NUM> and is formed of an elastically deformable material that may be repeatedly deformed and released (expanded). A base portion <NUM> of the compressive fit rod <NUM>, which forms a lower end of the compressive fit rod <NUM> that is seated in the bushing <NUM>, has a compressive fit with an interior wall <NUM> of the main body <NUM> of the bushing <NUM> that defines part of the axial bore <NUM>. The compressive fit may be less than ten percent. In exemplary embodiments, the compressive fit may be around five percent. The base portion <NUM> of the compressive fit rod <NUM> that engages with the interior wall <NUM> may constitute approximately half of a volume of the compressive fit rod <NUM>, and an axial length that is approximately half of a total axial length of the compressive fit rod <NUM> when the compressive fit rod <NUM> is in an expanded position. The expanded position is shown in <FIG> and <FIG> and the compressed position is shown in <FIG>.

The compressive fit rod <NUM> is expanded to the expanded position shown in <FIG> and <FIG> when the automated coupler parts <NUM>, <NUM> are decoupled. The expanded position may be an original or regular shape of the compressive fit rod <NUM>, such that the expanded position corresponds to a state in which the compressive fit rod <NUM> is relaxed. When the compressive fit rod <NUM> is in the expanded position, the shock isolator <NUM> is activated such that an axial end <NUM> of an upper portion <NUM> of the compressive fit rod <NUM> engages with the upper coupler part <NUM>. During decoupling of the automated coupler parts <NUM>, <NUM>, positive pressure is applied to the automated coupler parts <NUM>, <NUM> such that the upper coupler part <NUM> may rapidly accelerate upwardly and downwardly against the lower coupler part <NUM>. When the shock isolator <NUM> is expanded and thus activated, the compressive fit rod <NUM> of the shock isolator <NUM> extends outside the bushing <NUM> and is configured to absorb the excess shock energy generated by the decoupling. Accordingly, the activated shock isolator <NUM> prevents shock transfer between the automated coupler parts <NUM>, <NUM> and any damage to the component being vibration tested.

During coupling of the automated coupler parts <NUM>, <NUM>, the shock isolator <NUM> is disabled such that normal operation of the vibration testing unit <NUM> occurs and is unaffected by the implementation of the shock isolator <NUM>. When the shock isolator <NUM> is disabled, the upper portion <NUM> of the compressive fit rod <NUM> is deformed inside the bushing <NUM> by the force of the upper coupler part <NUM> moving to engage the lower coupler part <NUM>. The upper portion <NUM> of the compressive fit rod <NUM> is deformed inside the flange <NUM> of the bushing <NUM> such that the entire volume of the compressive fit rod <NUM> is surrounded by the bushing <NUM>.

The bushing <NUM> has a chamfer <NUM> that forms part of the axial bore <NUM>. The chamfer <NUM> is defined by a tapered surface that extends downwardly and radially inwardly from the upper surface <NUM> of the flange <NUM>. The chamfer <NUM> defines a chamfered volume <NUM> or a space between the bushing <NUM> and an outer peripheral surface of the compressive fit rod <NUM>. The chamfer <NUM> is formed to be engaged by the upper portion <NUM> of the compressive fit rod <NUM> when the compressive fit rod <NUM> is compressed inside the bushing <NUM>. When the compressive fit rod <NUM> is expanded to the expanded position, the compressive fit rod <NUM> disengages the chamfer <NUM> and the chamfered volume <NUM> is emptied to re-form the space between the chamfer <NUM> and the compressive fit rod <NUM>. The chamfered volume <NUM> is filled by the compressive fit rod <NUM> when in the compressed position. The chamfered volume <NUM> may be entirely filled by the deformed compressive fit rod <NUM>.

The chamfered volume of the bushing <NUM> may be formed to have any suitable dimensions. The tapered surface may extend an axial distance along the longitudinal axis L that is less than half of an entire axial length of the bushing <NUM>. The tapered surface may extend from the upper surface <NUM> of the flange <NUM> to the interior wall <NUM> of the main body <NUM>. In exemplary embodiments, the tapered surface may be angled by an angle θ that is between ten and <NUM> degrees relative to the longitudinal axis L. An angle θ of approximately <NUM> degrees may be suitable. Other angles may be possible depending on the application.

The compressive fit rod <NUM> is formed of any suitable elastomeric material that is able to be compressed without permanently deforming. When in the compressed position, the compressive fit rod <NUM> is arranged inside the bushing <NUM> such that only a portion of the compressive fit rod <NUM>, i.e. a compressible volume, deforms when the compressive fit rod <NUM> is compressed. The compressible volume corresponds to the chamfered volume of the bushing <NUM>. An axial length C of the compressible volume of the upper portion <NUM> of the compressive fit rod <NUM> may be ten percent or less of a total axial length T of the compressive fit rod <NUM>. When the compressive fit rod <NUM> is in the expanded position, the compressible volume of the upper portion <NUM> of the compressive fit rod <NUM> may extend upwardly outside or past the bushing <NUM> by the axial length C. Accordingly, by compressing only the compressible volume of the compressive fit rod <NUM>, the compression of the compressive fit rod <NUM> may have a linear profile, as compared with a non-linear compression profile that would result from compressing a larger axial length of the compressive fit rod <NUM>, such as over <NUM> percent.

The material of the compressive fit rod <NUM> is temperature resistant such that the material is able to maintain its material properties through hot and cold thermal conditions that may occur during vibration testing. The material may have a durometer that is medium hard, or a durometer that is in a Shore A hardness range of <NUM> to <NUM>. For example, a durometer of <NUM> or <NUM> may be suitable. The durometer may be dependent on the application. Examples of suitable materials include urethane, such as polyurethane, but other elastomeric materials having similar properties to polyurethane may be suitable. Other rubber materials or synthetic materials that are able to provide repeatability and withstand the various range of thermal conditions may be suitable.

The bushing <NUM> may be formed of any suitable material that is temperature resistant and able to withstand hot and cold thermal conditions. Suitable materials include thermoplastic polymer materials. Polyamide (nylon) is an example of a suitable material. Other materials having similar properties to polyamide may be suitable. Many other materials may be suitable and the materials may be dependent on the application.

The compressive fit rod <NUM> has a solid shape with an axially-extending through-aperture <NUM> that extends along the longitudinal axis L through the entire axial length T of the compressive fit rod <NUM>. The axially-extending through-aperture <NUM> enables the compressive fit rod <NUM> to return to the expanded position during decoupling. Without the axially-extending through aperture, a vacuum condition would occur that would prevent the compressive fit rod <NUM> from being released from the compressed position to the expanded position. The axially-extending through-aperture may have any suitable diameter, such as a diameter that is less than <NUM> percent of the diameter of the compressive fit rod <NUM>.

Referring now to <FIG> and <FIG>, further details of the inside of the bushing <NUM> and the compressive fit rod <NUM> are shown. <FIG> shows the axial bore <NUM> of the bushing <NUM>, as defined by the interior wall <NUM>, with which the compressive fit rod <NUM> has a press-fit or interference fit, and which extends upwardly from the inner radial surface <NUM>. The interior wall <NUM> extends to the tapered wall forming the chamfer <NUM> which defines another part of the axial port <NUM>. <FIG> also shows the chamfered volume <NUM> defined by the chamfer <NUM>. In an exemplary embodiment, the chamfered volume <NUM> may be between <NUM> cubic centimeters (<NUM> cubic inches) and <NUM> cubic centimeters (<NUM> cubic inches). Many other dimensions and shapes are suitable and may be dependent on the application.

As shown in <FIG>, the upper portion <NUM> of the compressive fit rod <NUM> has a compressible volume <NUM> that is approximately equivalent to the chamfered volume <NUM>. In an exemplary embodiment, the chamfered volume <NUM> is offset by between one and three millimeters, such as two millimeters. Accordingly, when the compressive fit rod <NUM> is in the expanded position within the bushing <NUM>, the compressive fit rod <NUM> is offset from the chamfer <NUM> by between one and three millimeters, such as two millimeters. The dimensions shown are merely exemplary and the shock isolator <NUM> may be sized up or down depending on the application.

Referring now to <FIG>, a method <NUM> of vibration testing using the vibration testing unit <NUM> of <FIG> to test a component is shown. Step <NUM> of the method <NUM> includes press-fitting a compressive fit rod <NUM> into a bushing <NUM> to form a shock isolator <NUM> (shown in <FIG>). More than one shock isolator <NUM> may be formed. Step <NUM> of the method <NUM> includes inserting one or more shock isolators <NUM> into a lower coupler part <NUM> of two automated coupler parts <NUM>, <NUM>, between the lower coupler part <NUM> and an upper coupler part <NUM> of the two automated coupler parts <NUM>, <NUM> (shown in <FIG>).

Step <NUM> of the method <NUM> includes coupling the two automated coupler parts <NUM>, <NUM> during vibration testing of a component. Step <NUM> of the method <NUM> includes compressing an upper portion <NUM> of the compressive fit rod <NUM> inside the bushing <NUM> to disable the one or more shock isolators <NUM> during the vibration testing and enable normal operation of the vibration testing. The compressive fit rod <NUM> is compressed by the engagement of the upper coupling part <NUM> against the lower coupling part <NUM>. Step <NUM> includes filling a chamfered volume <NUM> formed in an upper portion of the bushing <NUM> with a compressible volume <NUM> of the compressive fit rod <NUM> (shown in <FIG> and <FIG>). Step <NUM> may further include compressing the compressible volume <NUM> of the compressive fit rod <NUM> that has an axial length that is ten percent or less of a total axial length of the compressive fit rod <NUM>.

Step <NUM> of the method <NUM> includes decoupling the two automated coupler parts <NUM>, <NUM> after the vibration testing. Step <NUM> of the method <NUM> includes expanding the upper portion <NUM> of the compressive fit rod <NUM> upwardly from and outside the bushing <NUM> to activate the one or more shock isolators <NUM> and prevent shock transfer between the two automated coupler parts <NUM>, <NUM> when the two automated coupler parts <NUM>, <NUM> are decoupled, such that damage to the test component is prevented. Step <NUM> includes releasing or removing the compressible volume <NUM> of the compressive fit rod <NUM> from the chamfered volume <NUM> by way of the upper coupling part <NUM> disengaging from the lower coupling part <NUM>. When the shock isolators <NUM> are installed in the vibration testing unit <NUM>, the steps <NUM>-<NUM> of the method <NUM> may be repeated, such that the compressive fit rod <NUM> is repeatedly compressible and expandable during vibration testing.

Claim 1:
A shock isolator (<NUM>) arranged between automated coupler parts (<NUM>, <NUM>) in a vibration testing unit (<NUM>), the shock isolator comprising:
a bushing (<NUM>); and the shock isolator characterized in that it additionally comprises,
a compressive fit rod (<NUM>) supported in the bushing, the compressive fit rod being compressible inside the bushing to disable the shock isolator when the automated coupler parts are engaged during vibration testing, the compressive fit rod being expandable outwardly from the bushing to activate the shock isolator and absorb excess shock energy when the automated coupler parts are disengaged.