US3408852A - Timed impact tester - Google Patents

Description

1968 R. H. MARVIN TIMED IMPACT TESTER Filed Aug. 11, 1966 AB C D TIME SECONDS RINVENTOR RICHARD H. MARVIN AGENT Unied isms Paten 3,408,852 TIMEDIMPACT TESTER Richard HLMarvin, Philadelphia, Pa., assiguor to The Budd v .l l l nlmlly,-.Philadelphia, Pa.,'a corporation of. Pennsylvania 1 v g FiledAug.1I,1966, Ser. No. 571,91 T7,,Claims. (Cl. 73-12 A i ABSTRACT OF THE DISCLOSURE Apparatus for delivering a' series of impacts of con trolled impulse at accurate time intervals. 'A stationary piston at' one end "of "a cylinder engages ,the body, to be impacted. A rnovable piston is secured to the stationary pistonthrough. a tension rod having a notched insert. Fluid betweenthe pistons is raised to suflicient pressure to produce the, impact forceThe tension rod carriesthis force-andthe fluid is compressed. Explosive imeans wrappedabout'thenotched tension rod may be detonated to rupturethe Ibdl The time to actuate an adjacent like apparatusniay be controlled by the length of the connecting fuse. v 4 7 This-invention-relates to improved impact apparatus andrmore. -particularly, to such apparatus adapted to de liver a series of impacts time'intervalsa,

One environment in which the apparatus of the present inventionfind's use is in the application of a whipping test for ;seagoing1vessels.. The-typical'whipping test isan interpretatiori of--wave. s l-ap-on=.the.forward keelof ahull i from forces producing an essentially running load which diminishesrtin a forward direction: It is desired that the running load ;to-which-the ship is subjected be simulated byia-number {of equally. spaced impulsive forces consecu= tively at predetermined-short intervals, and lasting for a predetermined time duration. Various typesv of devices includingv rocketmotor .and'gun' type devices in which burning propellants generate animpulsive force were previously considered for use in solving this-problem but ity of energy storage cells;

I through one of energy cells 3,408,852 Pa en Y t% to the following description taken in connection with'j-th'e accompanying drawing and its scope will be pointed out in the appended claims. i g I i In the drawing FIG. 1.is a' schematicrepresentation of a test body which is subjected toaserie'sfofimpactsv apparatus of the present invention consisting of .ap ale FIG. 2 is a front elevational view of the'tes'tibfody shown in FIG. 1 and'showing lateral suppor'ts'fon each sideofthebody'; l

FIG. 3 is a .vertical sectional view partially schematic, 'of theapparlatus and showing the same connected in' series to other likeunits; 7 FIG. 4' shows a force-timegraph representing an' ill trative application of peaking'forces' ofithe e'nergy'stbrage units to the test body over a given time relationship.

. Referring toFI G. 1 of the drawing,.thef is' shown test body 10, which may be in the form of 'a,-seago'ing vessel, supported on a test bed.' 1'1, at load bearing supports 12, 13 along the length of its keel 14. The forwa'i'd portion 15 of the vessel and' its keel 'extend in cantilever relation to fixed support 13. A plurality of energy cells,

of controlled impulsefat.accurate were g-rejected as unsatisfactory in that none have been of controlled impulsive forces during predetermined time intervals; It is afurther object of this invention to provide an improved impact apparatus for storing a plurality 'of impulsivev forces -'which maybe triggered consecutively for immediate utilization and within an overall allowable time. 1

In accordance with theinvention the impact apparatus is positioned to apply an impulsive force against the test body and comprises energy container means havin movable means secured against relative movement by connecting means. A'fluid "medium .is supplied to the container means'with means for regulating its pressure. The connecting means resists the pressure and cooperates under stress to compress the fluid medium. Explosive charge means are suitably wrapped around the connecting means. Upon detonation the connecting means are ruptured and an impulsive force is applied by the apparatus to the test body.

For a better understanding of the present invention together with other and further objects, reference is had A, B, C, D, are interposed between the cantilevered portion of the keel and the test bed 11, and suitably arranged to apply forces simulating an essentially running load due to wave slap when travelling in a forward direction. As seen in FIG. 2 the vessel is shown supported in a vertical position by means of side supports 17, 18 disposed on opposite sides of the body and above the energy cells applied tothekeel14. '1 In the present instance each of the energy storage devices A, B, C, D, may be identical and for purposes .of simplicity only energy storage cell A is illustrated in detail. As seen in FIG. 3 energy device A is positioned inplace between keel 15 of the test body 10 and the t'estbedill. It comprises container means 20 which includes a cylinder 21 and a stationary piston 23 received within itsUpper end. The top surface 24 of the piston extends beyond the top edges of the walls of the cylinder and is securedto a high response fiat load cell 25. the load cell is, in. turn secured to a fitting 26 which is bolted by bolts 27. to the. keel 15 of the test body. The load cell 25 is .of convene: tional construction and is used to measure the.,. forces transmitted to the vessel. A movable piston 30 is p n; tioned within the bottom open end of the cylinder audit includes shoulder portions 31 which extend laterally or the cylinder and beneath the bottom edges of the cylinder. The latter piston includes an axially aligned aperture' 33 which opens from its top surface 34 and joins a slightly enlarged bore 35 which in turn extends to the. bottom snr, face 36 of the movable piston. A plurality of shock'ab sorbers 37 carried by a yokemember 38, resting on. test bed 11, engage the under surface 36 of the movable piston. Connecting means comprising an axially aligned rod. 41, and receiver means in the form of a rupture bolt 44 secure the movable piston 30 against movement. Axial rod 41 extends from the bottom surface 42 of stationary: piston 23 and passes through the aforementioned aperture 33 in the movable piston and into the bore 35. The lower, end of the rod includes an internally threaded portion 43 which receives the threaded shaft portion 45 of theten sion rupture bolt 44. The bolt includes a head 47 of greater diameter than the bore 35 and engages the bottom surface 36 of the movable piston. The bolt 44 moreover includes an undercut portion 49 along the length of its shaft which is in line with transverse apertures 50,;51 passing through the lower portion of the movable piston 30 and opening into the aforementioned vertical'bore 35.

A suitable supply of a fluid medium 55 under pressure such as hydraulic fluid F may be introduced into the cylinder 21 through aperture 56 within its sidewall by conduit means 57. The latter is shown as including a pressure between upper stationary pistonzs and lower piston 30 may be raised to a sufficient level to produce the maximum impact force applied through the load cell .25 and fitting Z6 onthe keel 15.The connecting means 19 com prising tension rod 41 and rupture bolt,44 carries this force .while the hydraulic fluid is compressed within the cylinder, Sintiethe" rupture bolt 44is reduced in crosssection as at 49, upon increase in pressure within the cylinder'the bolt becomes loaded under tension practically to its ultimate tensile strength. IA length ofcxp'losive charge material 61 is wrapped around the receivermeans at the notched portion of the tensilerupture bolt 44..One end of. the length 61 extends within' 'the transverse aperture '50of the movable piston and'the' other end is received in the oppositely located hore..51. A length offuse material L is shown connected to the explosive charge material 61 within bore 50 and the fus e L may be initiated by an electric initiator as at 63. When thefuse L and explosive chargeol are deto nated the notched rupture'rod 44 is ruptured by'virtue of its highYinitial stress and the shock of detonation. The load o'nthe keel will initially be the peak impact force.

The force will reduce as the movable piston 30 allows the hydraulic fluid F to expand. As seen in FIG. 4 the force time relationship designated by curve a is essentially triangular. The peak force is dependent upon the maximum fluid pressure. The duration of the applied force isdependent upon the yolume and compressibility of the fiuid. F and the mass of the stationary piston 23 and cylinder wall 21. i

A series of impact testors A, B, C, D, of the above description may be linked according to this invention with lengths Lb, Lo, and Ld of detonating fuse material to produce a series of forces and impulses of controlled magnitude at precise sequential time increments. The impulses so generated could thereby simulate a running load to'which a seagoing vessel is subjected. By assigning a line pressure, for example, of 5,000 lbs/in. to the storage cy1- inder A and using pressure regulators 58b, 58c, 58d, to respectively supply 4000, 3000, and 2000 lb./in. to the other cylinder (B, C, D) shown connected schematically series to cylinder A, substantially identical energy storage cylinders may be used. When so supplied with pressure the rupture bolts 44b, 44c, and 44d of the energy cells would be undercut in their respective notched portions 49b, 49c, 490! so that each would be stressed in tension an amount approaching the threshold of its ulti- .dma i aimmt einrentiqn audit, med in the P- pende'd claims to "eover all "siren" cherries and mesmertions as fall within the true spirit of the scope of the invention.

What is claimed is:

1. An impact apparatus for a test "body, comprising in combination, energy *storage containerf meahs secured-to saidbody,movable'means cooperating w storage container-,means to contain afiuid in, means' connecting said-movable piaris'to said container means, means for supplying a fiuid medium under pressure to said containerniEansYeXplosive charge means, said connecting means; haying ,;receive r rne ap s for said explosive charge v means, and means for initiating said explosivemea'ns to rupture said connecting -means, "whereby said fluid medium expands and'generates ari'impulsive force which istran'sniittedby said containsito saidte's't 2. In: the'ir'np'act apparatus as" set forth'in claim 1 wherein said movable means cooperating withsaiden'ergy storage container nieanscdnstitiits a pi st 3. 1m the "impact apparatus as set forth in' claim 2 wherein said means conne cting" saidmovable means to said energy storage'cor'itainer means includes tension rdd means passingth'rough-said piston.

4. In the impact apparagus as set forth in claim '3 wherein said tension 'rod means" comprises a rod extending from said energy storage containercmeans and partially through one end vof 'said piston and-a bolt including a notched'portion' entering andbottoming on the other end of said piston and threadedly connected to said rod. t r

.5. .Inthe impact apparatusas set forth in claim .4

' wherein said explosive charge means associated. with said means each secured tosaid body and comprising movable mate tensile strength. The above pressures when applied i to the respective cylinders would produce impulsive forces of a magnitude of 100,000; 80,000; 60,000; and 40,000 lbs./ sec. as seen in FIG. 4.

It is observed that "the length of fuse material Lb interconnects explosive charge 61 wrapped around bolt 44 to explosive charge 61b wrapped around bolt 44b. In a similar manner length Lc interconnects the other end of explosivecharge 61b to one end of explosive charge 610 wrapped around bolt 44c. Thereafter length Ld is connected to the opposite end of explosive charge 610 and connects the same to charge 61d encircling rupture bolt 44d. In each case the explosive charge material encircles the bolts at their necked down portions of reduced cross section. The time required to actuate the successive energy cells A, B, C, and D, is accurately controlled by each of the lengths, L, Lb, L0, and Ld, since the detonation rate is directly proportional to its length and is obtainable through calibration. i

While the"re has been described what at present is considered to be the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without meahscooperating-with said container means to'contairi a fluid medium therein, means connecting said movable means to each said container means, means for supplying a fiuid medium-under pressure to each said container means, explosive charge means, said connecting means having receiver means for said explosive charge means, and means linking'the' explosive chargemeans of each said energy storage container means in series to detonate the same at precise sequential time incrementsto rupture said connecting means, whereby said fluid medium in each of said energy storage container means expands and gen crates an impulsive. force which is transmitted by said container means to said test body. 2

7. In the impact apparatus as set forth in claim 6 wherein. the connecting means of each said energy storage means includes a rupture bolt having a shank portionreduced in cross section an 'amount such that when said .fluid medium under pressure is supplied to said cylinder means a the same causes said rupture bolt to be loadedin tension an amount approaching the ultimate-tensile strength of the rupture bolt. 'J

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