Abstract:
A portable electro-hydraulic test bed apparatus with analog control station and methodology for performing hands-on materials and components testing. A portable test bench is provided having a hydraulic pump and a reservoir of hydraulic oil. The pressurized hydraulic fluid flows through a pressure relief valve, filter, and ball valve to a servo control valve. The servo control valve controls the action of the hydraulic ram. Any return hydraulic fluid flows through check valve, filter, and heat exchanger back to the reservoir. The servo control valve with the hydraulic ram may be moved to the location where the test is to occur. Whenever the hydraulic ram is moved to a different location displacement interlock is also required. The hydraulic ram is anchored at one end and the test is performed on the test item with the other end of the ram. A displacement sensor is included to determine how much the test item is being displaced. In addition, a load cell is included to determine the load that is exerted on the test item. A portable analog control station is provided.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of The Invention  
           [0002]    Applicant&#39;s invention relates to a portable electro-hydraulic test bed apparatus with analog control station and methodology for performing hands-on materials and components testing.  
           [0003]    2. Background Information  
           [0004]    Engineering materials are commonly specified by their properties. Of all the properties a material may possess, mechanical properties are often the most important because virtually all fabrication processes and most service conditions involve some type of mechanical loading. Numerous products exist in the marketplace that are used to evaluate the mechanical and physical properties and performance of materials, structures and components. However, the majority of these products are large, cumbersome and lack cost effectiveness. A need therefore exists in the industry for an inexpensive and portable test bench that can perform a series of mechanical structure tests. Applicant has sought to satisfy this need with the present invention.  
         SUMMARY OF THE INVENTION  
         [0005]    It is an object of the present invention to provide a novel portable electro-hydraulic test bed apparatus with analog control station and methodology for performing hands-on materials and components testing.  
           [0006]    Still another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which incorporates a hydraulic ram.  
           [0007]    Another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which incorporates an analog control system.  
           [0008]    Still another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus wherein the control system is an analog closed loop control system which uses force or displacement as the feedback parameter.  
           [0009]    Yet another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which provides a displacement interlock control.  
           [0010]    An additional object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which incorporates a hydraulic pump.  
           [0011]    Still an additional object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which incorporates at least one oil filter.  
           [0012]    Yet an additional object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which incorporates a valve control system.  
           [0013]    Another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which provides a portable test bench.  
           [0014]    Still another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which provides a pressure relief valve.  
           [0015]    Another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which provides a ball valve.  
           [0016]    Still an additional object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which incorporates a servo control valve.  
           [0017]    Yet an additional object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which incorporates a check valve.  
           [0018]    Still another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which incorporates a displacement sensor.  
           [0019]    Another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which provides at least one control card.  
           [0020]    It is yet another object of the present invention to provide a novel portable electro-hydraulic test bed apparatus which incorporates a load/force sensor.  
           [0021]    An additional object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which incorporates a hydraulic manifold.  
           [0022]    Still another object of the present invention is to provide a novel portable electro-hydraulic test bed apparatus which provides a hydraulic pump motor.  
           [0023]    It is another object of the present invention to provide a novel portable electro-hydraulic test bed apparatus which incorporates safety devices.  
           [0024]    In satisfaction of these and related objectives, Applicant&#39;s present invention provides a portable electro-hydraulic test bed apparatus with analog control station and methodology for performing hands-on materials and components testing. A portable test bench is provided that has a hydraulic pump and a reservoir of hydraulic fluid. The pressurized hydraulic fluid flows through a pressure relief valve, filter, and ball valve to a servo control valve. The servo control valve controls the action of the hydraulic ram. Any return hydraulic fluid flows through check valve, filter, and heat exchanger back to the reservoir. The servo control valve with the hydraulic ram may be moved to the location where the test is to occur. Whenever the hydraulic ram is moved to a different location the need to include displacement interlock is required as well. The hydraulic ram is anchored at one end and the test is performed on the test item with the other end of the ram. A displacement sensor is included to determine how much the test item is being displaced during the test. In addition, a load cell is included to determine the load that is exerted on the test item.  
           [0025]    The portable work bench can be located outside the item to be tested, but the hydraulic hoses and control cable would run into the test item. The hydraulic ram could be set inside the test item and the tests performed within the test item. The person performing the test can also have the control station for the apparatus adjacent him or her when watching the test from within the test item since the control station is on a tethered cable.  
           [0026]    The control system of the present invention operates based on the manner in which the actuating signal is used to control the transfer of energy from source to load. The control system underlying the present invention is an analog closed loop control system. Essentially the control system operates on continuously varying data whereby any output force or displacement signal from the test item is fed back into the system for comparison with the initial resting state values and any interim testing values. The control system provides control to within an accuracy of 0.05% of the command in the elastic range of the article being tested. This type of control is advantageous over digital control since digital control only works in discrete units and is therefore referred to as discontinuous control. The control station of the present invention indicates to the test engineer system response values during the test and the continuous nature of the control system allows for precision control and adjustment instantly during a test. The system is capable of holding load and relieving load at the discretion of the engineer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    [0027]FIG. 1 is a perspective view of the preferred embodiment of the present invention.  
         [0028]    [0028]FIG. 2 is a top view of the preferred embodiment of the present invention.  
         [0029]    [0029]FIG. 3 is a front cross-sectional view of the preferred embodiment of the present invention.  
         [0030]    [0030]FIG. 4 is a schematic of the hydraulic and electrical assembly of the preferred embodiment of the present invention.  
         [0031]    [0031]FIG. 5 is a close up view of the hydraulic ram of the preferred embodiment of the present invention.  
         [0032]    [0032]FIG. 6 is a close up view of the strain assembly which can be used with the preferred embodiment of the present invention.  
         [0033]    [0033]FIG. 7 is a close up view of the displacement interlock control of the preferred embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0034]    [0034]FIG. 1 is a perspective view of the preferred embodiment of the present invention  100 . A test bench  101  is provided being preferably rectangular in shape and having top  101   a , bottom  101   b  and sides  101   c . Test bench  101  is preferably supported from bottom  101   b  by a stabilizing number of wheels  102  near the front end  103  and rear end  104  of test bench  101 . Wheels  102  are mounted to the bottom  101   b  by way of support brackets  105 . Support brackets  105  connect to forks  106  on opposing sides of each wheel  102 . Forks  106  connect to wheel  102  by way of hub  107 . Wheels  102  are provided to give mobility to test bench  101 . Locking means  108  is provided on at least two of the wheels  102  to lock test bench  101  in location before and after moving.  
         [0035]    On the side  101   c  of test bench  101  is a control interface case  109 . Control interface case  109  serves as the power interface for test bench  101 . At control interface case  109 , 0-10 volt DC fixed power source  109   a  is provided as well as a 24 volt DC regulated power source  109   b . A proportional integral derivative (PID) module  109   c  is incorporated to regulate various process parameters such as pressure, total mass flow rate, phase volumetric fraction, phase mass flowrate, and pressure and liquid level. The regulation by the PID module  109   c  is accomplished by controlling outlet pressure, inlet total mass flowrate, valve opening and pump velocity. Control interface case  109  also provides a ramp module  109   d . Ramp module  109   d  produces a DC output signal over an adjustable time rate setting based on the closure of an external contact. Ramp module  109   d  can have integral LED&#39;s indicating that its output is at minimum, or has reached a maximum output state. Ramp module  109   d  is useful for establishing the rate in which to achieve a predetermined tensile or compressive load/force measured by load/force cell  138  or a physical displacement of rod  136  measured by displacement transducer  113 . The ramp rate is established by an adjustable rate knob located on control station  110 . The preferred specifications for ramp module  109   d  are contained in Table 1.  
                         TABLE 1                       Preferred Specifications of Ramp Module 109d.                                Power Supply   Regulated 18-26 VDC       Power Required   4 VA       Command Signal   0 to +10 VDC and 0 to −10 VDC       Ramp Disable Voltage   5 to 30 VDC       Reference Outputs   +/− 10 VDC @10 ma       Output Voltage   0 to +/− 10 VDC       Ambient Temperature Range   32 F. to 158 F. standard       Ramp Time   Adjustable                  
 
         [0036]    The control system underlying the present invention is an analog closed loop control system. In this arrangement, the control system operates on continuously varying data whereby any output force or displacement signal from the test item is fed back into the system for comparison with initial resting state values and any interim testing values. The control system provides control to within an accuracy of 0.05% of the command in the elastic range of the article being tested.  
         [0037]    On top  101   a  of test bench  101  is control station  110 , displacement interlock control  111 , and hydraulic ram  112 . Control station  110  maintains four display units for monitoring force feedback measured by load/force cell  138 , displacement feedback measured by displacement transducer  113 , command high setpoint and command low setpoint. Also maintained on control station  110  are analog controls with actuator knobs and switches  121  having the functions COMMAND SELECT (HIGH/ZERO/LOW), COMMAND HIGH SETPOINT, COMMAND LOW SETPOINT, RAMP ENABLE, RAMP RATE-SELECTABLE, CONTROL SELECT (FORCE OR DISPL) used in controlling the present invention. The control station  110  indicates to the test engineer system response values during the test and the continuous nature of the control system allows for precision control and adjustment instantly during a test. The control system through control station  110  is capable of holding load and relieving load at the discretion of the test engineer.  
         [0038]    Control station  110  is connected to test bench  101  through a tethered cable  117  (See FIG. 2). Hydraulic ram  112  is used for supplying tension or compression to the item being tested. Hydraulic ram  112  is a single-acting cylinder with a single diameter ram type plunger incorporating a “tie rod” design. The preferred specifications for the hydraulic ram  112  are contained in Table 2.  
                             TABLE 2                       Preferred Specifications for Hydraulic Ram 112.                                    Nominal Pressure   1000 psi dependent on bore size           Standard Temperature   −10 F. to +165 F.           Bore Size   1 inch through 8 inches           Piston Rod Diameter   ½ inch through 5½ inches                      
 
         [0039]    Hydraulic ram  112  is connected to the top of level plate  120  at one end of hydraulic ram  112  by way of hydraulic ram rod end cover  124   a . The opposite end of hydraulic ram  112  is directly connected to test bench  101  by way of hydraulic ram head end cover  124   b . Positioned on top of hydraulic ram head end cover  124   b  is hydraulic manifold  129 . Pressure line  116  carries fluid from hydraulic pump  161  (See FIG. 3) to the hydraulic manifold  129  of hydraulic ram  112  by way of union  131 . Return line  114  carries exhaust fluid from the hydraulic manifold  129  of hydraulic ram  112  back to the oil reserve  151  (See FIG. 3). On top of hydraulic manifold  129  is valve  126 . Servo cable  115  is connected to valve  126  by way of coil (not shown) under housing  127 . Servo cable  115  supplies a combined transmission of power and control to coil (not shown). Coil (not shown) drives valve  126  which directs fluid into hydraulic manifold  129 . Level plate  120  may or may not be attached to top  101   a  of test bench  101  by way of screws  123 .  
         [0040]    Connected by way of displacement transducer mounts  128  at the side of hydraulic ram  112  is displacement transducer  113 . Displacement transducer  113  is provided to measure hydraulic ram  112  stroke. Base mount  122  is located adjacent hydraulic ram head end cover  124   b  and connected to hydraulic ram head end cover  124   b  by way of mated arms  134 . Mated arms  134  include two stationary arms  134   a  situated horizontally on top of base mount  122  and one movable arm  134   b  extending pivotally from hydraulic ram head end cover  124   b . Stationary arms  134   a  and movable arm  134   b  are connected by way of screws  135 .  
         [0041]    Extending on the opposite side of hydraulic ram rod end cover  124   a  portion of the hydraulic ram  112  is rod  136 . The opposite end of rod  136  connects to one face of plate  137 . Adjacent the opposing face of plate  137  is load/force cell  138 , being preferably an S-beam. Load/force cell  138  measures the load provided by hydraulic ram  112 . On the opposite side of load/force cell  138  are two strain inducers  139  with a centrally connected test specimen  118 . The strain inducer  139  induces strain into the test item  118  which can be measured preferably with a strain gauge (not shown). The applied force can be either positive (tensile) or negative (compressive). Connected at the opposite end of the second strain inducer  139  is reaction mount  119 . Reaction mount  119  mounts to test bench  101 .  
         [0042]    Situated above plate  137  and load/force cell  138  are arms  140  of displacement interlock control  111 . At the opposite end of arms  140  are interlocks  141 . Interlocks  141  are provided to prevent or allow a movement or operation of one part, only when the other part is locked in a pre-determined position. Interlocks  141  are situated on bars  142  which end in a central member  143 . Base member  148  anchors displacement interlock control  111  to test bench  101  by way of platform  149 . Safety devices consisting of multi-directional displacement interlocks  141 , an easily accessible hydraulic pressure ON/OFF master switch  159  and an adjustable pressure relief valve  153 . These safety devices provide the test bench  101  means to prevent overloading of the sample test item  118  during normal operation. These safety devices are capable of relieving pressure upon actuation.  
         [0043]    In FIG. 2 a top view of the preferred embodiment of the present invention is shown. On top of test bench  101  is control station  110 , displacement interlock control  111 , and hydraulic ram  112 . Control station  110  contains actuator knobs  121  used in controlling the hydraulic ram  112  of the present invention. Control station  110  is connected to test bench  101  through a tethered cable  117 . Hydraulic ram  112  is connected to the top of level plate  120  at one end of hydraulic ram  112  by way of hydraulic ram rod end cover  124   a . On top of hydraulic ram rod end cover  124   a  is union  130  which provides a connection to tube  125 . Pressure line  116  carries fluid from hydraulic pump  161  (See FIG. 3) to the hydraulic ram  112  by way of union  131 . Return line  114  carries exhaust fluid from the hydraulic ram  112  back to the oil reserve  151  (See FIG. 3) by way of union  133 , check valve  150 , and union  132 . Valve  126  is provided. Servo cable  115  is connected to valve  126  by way of coil (not shown) under housing  127 . Servo cable  115  supplies a combined transmission of power and control to valve  126 . Level plate  120  may or may not be attached to top  101   a  of test bench  101  by way of screws  123 . Connected by way of displacement transducer mounts  128  at the side of hydraulic ram  112  is displacement transducer  113 . Displacement transducer  113  is provided to measure hydraulic ram  112  stroke. Base mount  122  is provided.  
         [0044]    Extending on the opposite side of hydraulic ram rod end cover  124   a  portion of the hydraulic ram  112  is rod  136 . The opposite end of rod  136  connects to one face of plate  137 . Adjacent the opposing face of plate  137  is load/force cell  138 , preferably an S-beam. On the opposite side of load/force cell  138  are two strain inducers  139  with a centrally connected test specimen  118 . Connected at the opposite end of the second strain inducer  139  is reaction mount  119 . Reaction mount  119  mounts to test bench  101 .  
         [0045]    Situated above plate  137  and load/force cell  138  are arms  140  of displacement interlock control  111 . At the opposite end of arms  140  are interlocks  141 . Interlocks  141  are situated on bars  142  which end in a central member  143 . A means  144  for adjusting bars  142  is provided. Located centrally on central member  143  is side member  145 .  
         [0046]    In FIG. 3 a front cross-sectional view of the preferred embodiment of the present invention is shown. Test bench  101  having wheels  102  mounted to the bottom of test bench  101  by way of support brackets  105  is provided. Support brackets  105  connect to forks  106  on opposing sides of each wheel  102 . Forks  106  connect to wheel  102  by way of hub  107 . Locking means  108  is shown.  
         [0047]    Control interface case  109  is provided and serves as the power interface for test bench  101 . At control interface case  109 , 0-10 volt DC fixed power source  109   a  (See FIG. 1) is provided as well as a 24 volt DC regulated power source  109   b  (See FIG. 1). A proportional integral derivative (PID) module  109   c  (See FIG. 1) is incorporated to regulate various process parameters such as pressure, total mass flow rate, phase volumetric fraction, phase mass flow rate, and pressure and liquid level. The regulation by the PID module  109   c  (See FIG. 1) is accomplished by controlling outlet pressure, inlet total mass flow rate, valve opening and pump velocity. Control interface case  109  also provides a ramp module  109   d  (See FIG.  1 ). Ramp module  109   d  (See FIG. 1) produces a DC output signal over an adjustable time rate setting based on the closure of an external contact. Ramp module  109   d  (See FIG. 1) can have integral LED&#39;s indicating that its output is at minimum, or has reached a maximum output state. Ramp module  109   d  (See FIG. 1) is useful for establishing a rate in which to achieve a pre-established setpoint or output state.  
         [0048]    On top of test bench  101  is control station  110 , displacement interlock control  11 , and hydraulic ram  112 . Control station  110  contains actuator knobs  121  (See FIG. 2) used in controlling the hydraulic ram  112  of the present invention. Control station  110  is connected to test bench  101  through a tethered cable  117  which connects to control interface case  109 , more particularly ramp module  109   d  (See FIG. 4).  
         [0049]    Hydraulic manifold  129  is provided on hydraulic ram  112 . Pressure line  116  carries fluid from oil reserve  151  to the hydraulic manifold  129  of hydraulic ram  112 . Initially hydraulic fluid travels from oil reserve  151  into line  164  through hydraulic pump  161  where it is pressurized. The preferred specifications for the hydraulic pump  161  are included in Table  3 . A thermostat (not shown) is provided on oil reservoir  151  to visually monitor the temperature. Pressurized hydraulic fluid then enters pressure line  116  and goes through relief valve  153 , pressure gauge  154 , and oil filter  155  before entering hydraulic manifold  129  by way of union  131  (See FIG. 2). Return line  114  carries exhaust fluid from the hydraulic manifold  129  of hydraulic ram  112  back to the oil reserve  151  after passing through oil filter  160  and heat exchanger  152 . On top of hydraulic manifold  129  is valve  126 . Servo cable  115  is connected to valve  126  by way of coil (not shown) under housing  127 . The opposite end of servo cable  115  is connected to control interface case  109 , more particularly PID module  109   c  (See FIG. 4).  
                             TABLE 3                       Preferred Specifications for Hydraulic Pump 161.                                    Operating Pressure   3000 psi           Filtration   3 micron or less           Recommended Temperature Range   40 F. to 180 F.           Power   110 VAC 30 AMP                      
 
         [0050]    Displacement transducer  113  (See FIG. 1) is provided to measure hydraulic ram  112  stroke. A displacement transducer cable  156  connects displacement transducer  113  to control interface case  109 , more specifically PID module  109   c  (See FIG. 4).  
         [0051]    On one end of the hydraulic ram  112  is rod  136 . A load/force cell  138 , preferably an S-beam, is provided. Load/force cell  138  measures the load provided by hydraulic ram  112 . A load/force cell transducer cable  157  connects load/force cell  138  to control interface case  109 , more particularly, PID module  109   c  (See FIG. 4). On the opposite side of load/force cell  138  are two strain inducers  139  with a centrally connected test specimen  118 . Connected at the opposite end of the second strain inducer  139  is reaction mount  119 . Reaction mount  119  mounts to test bench  101 .  
         [0052]    A 110 VAC 30 amp circuit  194  provides power to master switch  159  via line  190 . Master switch  159  provides power to hydraulic pump motor  191 . A standard voltage 110 VAC plug  158  is provided for electrically connecting test bench  101  to a standard outlet (not shown). Power from 110 VAC plug  158  is provided to panel  195  which directs power to control interface case  109  and 24 volt transformer  192 . Transformer  192  feeds power into relay (not shown) in master switch  159 . Power from this transformer  192  is ultimately used to provide power to displacement interlock control  111 .  
         [0053]    [0053]FIG. 4 is a schematic of the hydraulic and electrical assembly of the preferred embodiment of the present invention. The operation of the present schematic takes place on test bench  101  (See FIG. 1). Test bench  101  (See FIG. 1) has hydraulic pump  161  and oil reserve  151 . Hydraulic fluid flows from oil reserve  151  into line  164  and into hydraulic pump  161 . Hydraulic fluid then passes through hydraulic pump  161  and enters pressure line  116 . The pressurized hydraulic fluid then flows through relief valve  153 , oil filter  155  and ball valve  162  to a servo control valve  163 . Servo control valve  163  controls the action of hydraulic ram  112 . The preferred specifications for the servo control valve  163  are found in Table 4. Any return hydraulic fluid flows into return line  114  through check valve  150 , oil filter  160 , and heat exchanger  152  back to oil reserve  151 . Relief valve  153  can pass relieved fluid into return line  114  for return to oil reserve  151 .  
                             TABLE 4                       Preferred Specifications for Servo Control Valve 163.                                    Rated Flow @1000 psi   3.78-151 LPM (1.0-4.0 GPM)           Linearity   ≦5%           Hysteresis   ≦5%           Threshold   ≦5%           Operating Temperature   30 to 225 F.           Pressure Gain   3% of spool shift           Null Shift   With temp. ≦±2% per 100 F.               With supply press &lt;2% per 1000 psi           Quiescent Flow   1.5-2.1 LPM (.40-.55 GPM)                      
 
         [0054]    Servo control valve  163  with hydraulic ram  112  can be moved to the location where a test is to be performed. A displacement transducer  113  is included to determine how much a test item displaced. In addition, load/force cell  138  is provided to determine the load that is exerted on a test item.  
         [0055]    PID module  109   c  operates displacement transducer  113  and load/force cell  138 . A valve driver card (not shown) is provided within PID control module  109   c  which operates servo control valve  163 . PID module  109   c  connects to servo control valve  163  by way of servo cable  115 , to displacement transducer by way of displacement transducer cable  156 , and to load/force cell  138  by way of load/force cell transducer cable  157 . A ramp card (not shown) is provided within ramp module  109   d  which is responsible for receiving feedback signals from displacement transducer  113  and load/force cell  138 . Ramp module  109   d  connects to control station  110  by way of tethered cable  117 . A 24 volt DC regulated power source  109   b  provides power to PID module  109   c  and ramp module  109   d.    
         [0056]    A 110 VAC 30 amp circuit  194  provides power to master switch  159  via line  190 . Master switch  159  provides power to hydraulic pump motor  191 . A relay (not shown) within master switch  159  provides power to displacement interlock control  111 .  
         [0057]    In FIG. 5 a close up view of the hydraulic ram of the preferred embodiment of the present invention is shown. Hydraulic ram  112  is connected to the top of level plate  120  at one end of hydraulic ram  112  by way of hydraulic ram rod end cover  124   a . The opposite end of hydraulic ram  112  is directly connected to test bench  101  (See FIG. 1) by way of hydraulic ram head end cover  124   b . Hydraulic ram rod end cover  124   a  and hydraulic ram head end cover  124   b  are connected by way of ram member  173  and rods  125 ,  172 ,  174  and  175 . Tube  125  is connected to hydraulic manifold  129  and hydraulic ram rod end cover  124   a  by way of nuts  170   a  and  170   b . Nut  170   b  connects directly to hydraulic manifold  129  and nut  170   a  connects to union  130  on nut  168  of hydraulic ram rod end cover  124   a . Positioned on top of hydraulic ram head end cover  124   b  is hydraulic manifold  129 . Pressure line  116  carries fluid from hydraulic pump  161  (See FIG. 3) to the hydraulic manifold  129  of hydraulic ram  112  by way of union  131 . Return line  114  carries exhaust fluid from the hydraulic manifold  129  of hydraulic ram  112  back to the oil reserve  151  (See FIG. 3) by way of union  133 , check valve  150  and union  132 . On top of hydraulic manifold  129  is valve  126  connected by way of mount  171 . Servo cable  115  is connected to valve  126  by way of coil (not shown) under housing  127  and mount  166 . Level plate  120  may or may not be attached to top  101   a  of test bench  101  by way of screws  123 .  
         [0058]    Connected by way of displacement transducer mounts  128  at the side of hydraulic ram  112  is displacement transducer  113 . Base mount  122  is located adjacent hydraulic ram head end cover  124   b . Base mount  122  connects to test bench  101  by way of screws  167  and connects to hydraulic ram head end cover  124   b  by way of mated arms  134  (See FIG. 1). Mated arms  134  (See FIG. 1) include two stationary arms  134   a  and one movable arm  134   b  (See FIG. 1). Stationary arms  134   a  and movable arm  134   b  (See FIG. 1) are connected by way of screws  135 .  
         [0059]    Extending on the opposite side of hydraulic ram rod end cover  124   a  portion of the hydraulic ram  112  is rod  136 . Rod  136  connects to hydraulic ram rod end cover  124   a  by way of dowel  169 . The opposite end of rod  136  connects to one face of plate  137 .  
         [0060]    [0060]FIG. 6 is a close up view of the strain assembly which can be used with the preferred embodiment of the present invention. This strain assembly is only required to assist in the understanding of the preferred embodiment, but is not required to operate the present invention. Rod  136  connects to one side  138   a  of load/force cell  138 . Load/force cell  138  is preferably an S-beam. On the opposite side  138   b  of load/force cell  138  is strain connecting member  176 . Strain connecting member  176  connects to one strain inducer  139 . Strain inducer  139  is composed of a u-shaped member  139   a  and a flat member  139   b . Flat member  139   b  fits partially within the u-portion of u-shaped member  139   a  at one end of flat member  139   b  and is secured to u-shaped member  139   a  by way of screw  139   c . The other end of flat member  139   b  is connected to test specimen  118 . A second strain inducer  139  oriented the opposite direction is connected to the opposing side of test specimen  118 . Second strain inducer  139  is connected to reaction mount  119 . Reaction mount  119  has a back  119   a , side  119   b , cavity  119   c  and bottom  119   d . Bottom  119   d  of reaction mount  119  attaches to test bench  101  (See FIG. 1).  
         [0061]    In FIG. 7 a close up view of the displacement interlock control of the preferred embodiment of the present invention is shown. Situated above plate  137  (See FIG. 5) and load/force cell  138  (See FIG. 6) are arms  140  of displacement interlock control  111 . At the opposite end of arms  140  are interlocks  141 . Interlocks  141  are situated on bars  142  connected by way of connectors  178 . Bars  142  end in a central member  143 . A means for adjusting bars  144  is provided having wing nuts  179  for ease of tightening and loosening the connection of bars  142  to central member  143  and to allow the movement of bars  142  along central member  143 . Central member  143  connects at the side of its length to side member  145 . Side member  145  connects to post  146 . An adjustment means  147  is provided between side member  145  and post  146  to allow the adjustment of post  146  in relation to side member  145 . Adjustment means  147  is preferably a wing nut. Post  146  connects into pivot means  180  which allows pivotal vertical movement of post  146  in relation to base member  148 . Rotation means  181  is provided surrounding pivot means  180  which allows rotation of post  146  in a horizontal plane in relation to base member  148 . Locking means  182  is connected to rotation means  181  and allows locking of movement of pivot means  180  and rotation means  181  after movement. Base member  148  having feet  183  anchors displacement interlock control  111  to test bench  101 (See FIG. 1) by way of platform  149 .  
         [0062]    Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon the reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.