US3165916A - Noise-reducing structure - Google Patents

Noise-reducing structure Download PDF

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Publication number
US3165916A
US3165916A US165162A US16516262A US3165916A US 3165916 A US3165916 A US 3165916A US 165162 A US165162 A US 165162A US 16516262 A US16516262 A US 16516262A US 3165916 A US3165916 A US 3165916A
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US
United States
Prior art keywords
explosive
chamber
strain
noise
sphere
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US165162A
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English (en)
Inventor
Jr Frank Abraham Loving
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EIDP Inc
Original Assignee
EI Du Pont de Nemours and Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE626423D priority Critical patent/BE626423A/xx
Priority to NL287590D priority patent/NL287590A/xx
Application filed by EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Priority to US165162A priority patent/US3165916A/en
Priority to GB43405/62A priority patent/GB1007477A/en
Priority to FR915884A priority patent/FR1341780A/fr
Priority to LU42988D priority patent/LU42988A1/xx
Priority to DEP30919A priority patent/DE1186384B/de
Application granted granted Critical
Publication of US3165916A publication Critical patent/US3165916A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D5/00—Safety arrangements
    • F42D5/04—Rendering explosive charges harmless, e.g. destroying ammunition; Rendering detonation of explosive charges harmless
    • F42D5/055—Silencing means for blasting operations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D26/00—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces
    • B21D26/02—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure
    • B21D26/06—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure by shock waves
    • B21D26/08—Shaping without cutting otherwise than using rigid devices or tools or yieldable or resilient pads, i.e. applying fluid pressure or magnetic forces by applying fluid pressure by shock waves generated by explosives, e.g. chemical explosives
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B33/00—Manufacture of ammunition; Dismantling of ammunition; Apparatus therefor
    • F42B33/06—Dismantling fuzes, cartridges, projectiles, missiles, rockets or bombs
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/22—Fuels; Explosives
    • G01N33/227—Explosives, e.g. combustive properties thereof

Definitions

  • W P-K in which P is the equivalent hydrostatic pressure in pounds/square inch which must be contained without exceeding the permissible .strain on the structure, Kis a constant characteristic of the explosive being used, W is the weight of the explosive in pounds, and V is the volume in cubicfeet enclosed by thestructure.
  • this invention provides a noise-reducing structure which comprises a chamber, said chamber having walls of sufficient mass and tensile strength to withstand the equivalent internalghydrostatic working pressure, P, inpound s/square inch, in accordance of the equation:
  • K is an empirical constant depending upon the explosive used
  • W is the weight of the explosive in pounds
  • V the volume, enclosed by a given structure.
  • P a given equivalent hydrostatic pressure
  • the weight of the explosive charge which may be detonated without damaging the enclosing structure cannot be increased without a proportionate increase in the volume of a structure having givenstrength characteristics.
  • V is the volume of the empty chamber measured in cubic feet; a closable access means into said chamber; a noise-muffiing gas-venting means emanating from said chamber; and amass of loose granular solid occupying a segment of said chamber, the height of said segment being about to /2 of the height of said chamber.
  • the shape and construction of the substantially closed noise-reducing chamber will depend on a variety of factors. Desirably, the structure will be free ofsharp angular-joints which lead to localized concentrations of stress.
  • the preferred design is defined as a chamber, or structure,
  • the structure may be positioned with its longitudinal axis either horizontally -or vertically, the horizontal position being preferred.
  • the structure may be made of any material having relatively high tensile strength andresistance to brittle fracture under the conditions of use. However, considerations of cost, availability, ease of fabrication, and
  • steels of Type T-l made by the United States Steel Corporation and ASTM Types A212B and A-201.
  • the structure may be madetof a single thickness of steelor may be a sandwich construction consisting, for example, of two sheets of steel .and an interposed layer of concrete.
  • the walls, of .theshell must be capable of withstanding the complex pressure pulse developed by the detonation of the explosive charge within the chamber.
  • Thestrength of the wall required to-withstand the pressure pulses generated by detonation of an-explosive within the structure is a function oflthevolume of the chamber, thepkindof explosivedetonated, the weight of the explosive which is detonated, and theyield-strength of the material of which the chamber is constructed.
  • K used in this expression depends not only on the strength of the explosive but also on the completeness of reaction for the explosive decomposition under thegstrain to be expected in a the conditions which prevail in the noise-reducing chamber.
  • the value of K equals2 1O for trinitro- 'toluene (TNT), 1.5 x 10 for pentaerythritol tetranitrate (PETN), and 7X 10 for 40% dynamite.
  • PETN has a higher available explosive energy per unit weight (1300 kcaL/kg.) than does TNT (about 860 kcal./kg.)
  • a higher value of K is used for .TNT than for PETN because of the reaction with air of the initial detonation products of highly oxygen-deficient TNT.
  • the rather low K for the 40% dynamite is ascribed at least in part to the incomplete reaction of the ingredients in the absence of a high degree of confinement such as prevails under the usual conditions of use in a borehole.
  • FIGURE '1 depicts, partially in section, a particularly preferred embodiment of thisinvention.
  • 1 represents the steel shell, spherical in shape
  • '2 represents an access door, preferably inwardly opening
  • 3 represents a supporting cradle, also of steel
  • 4 represents a supporting base, for example, reinforced concrete
  • 5 represents a steel vent-tube welded to the shell and connected to'a gas mufiler 6 by flanges 7 '-which have between them a ste'el'grating8 which sup- .ports the filling of lightweightichain 9 which provides a devious path for the explosion gases as theyjpass through mufiler 6.
  • alayer of dense granular or particulate material 10 'for example sand 'or crushed limestone; Not shown are retaining hooks weld .ed to shell l'to position explosive charges within the V shell and electrical conduits for ignition circuits and instrument circuits. Additionally, other openings with suitable closures may be included for making photographic studies, for forced ventilation, and the like.
  • the granular material While positioning of the granular material in other locations may be feasible, I prefer to place the granular material in the bottom of the structure where it can be used as a support for the explosive-bearing assembly and where gravitational forces will keep the material in substantially a fixed and uniform location.
  • T o minimize the creation of undesirable noises in venting the explosion-generated gases from the chamber
  • mufiling device preferably is incorporated in the vent.
  • chain in a cylindrical .housing is used to create a devious path for the gases.
  • FIGURE 2 illustrates the strain-time relationships which resulted from detonations within a noise-reducing structure of FIGURE 1 when empty and when different amounts of loose granular solid were present, as described in Example 1.
  • Example 1 A 12-foot sphere was made having a shell wallfof %-inch-thick steel, an access opening approximately 5 feet high and 2 /2 feet widelocated. approximately halfway between the bottom and top of the sphere and fitted with an inwardly opening door, and mounted on top of the sphere a mutller comprising an IS-inch-diameter by 4-foot-long steel cylinder having a steel support grating between the sphere and the lower endof the cylinder, the space above the grating being substantially filled with a packing of lightweight chain. The sphere was supported in a steel cradle on a concrete base.
  • Calibrated strain gages were mounted'on the external surface of the sphere to measure the strain, i.e., the deformation per unit length producedin the steel shell by the detonation of-12-pound charges of TNT suspended substantially in the middle of the sphere.
  • the gages were connected to an oscillograph which made a record of the variation in displacement with time. 'By use of a calibration factor, the displacement was expressed as strain in microinches/inch. Measurements ,were made both before vand 1 after placing sand in the spherical structure, withresultsas shown in'FIGURE-Z and in the table below.
  • FIGURE 2 shows that the maximum strain (M)'in the empty spherical structure (graph A) occurred a few milliseconds after the initial pressure pulse (I). In the presence of a 1-foot segment of sand, however, the maximum strain (M) was reduced (graph B). With approximately a 2-foot segment of sand in the sphere (graph C), the maximum strain coincided with the initial strain. This amount of sand therefore represents substantially the optimum quantity,
  • the sphere before the reduction in volume is such that i.e., the quantity .of sand whichpermits detonating maximum charges o-fexplosive with- 'out exceeding the permissible strain onthe sphere.
  • the segment occupied by loose granular material can be in- .creased to a thickness equal to one-half the height of 33 strain, reaches the level of the maximum strain produced by detonation of an equivalent charge in the empty spherical structure.
  • the numerical data corresponding to the strain graphs of FIGURE 2 are shown in the table below.
  • Amatol was spread uniformly over the surface of a 1- foot x 5-foot rectangular metal plate resting on the surface of a 2-foot-high segment of loose sand contained in the spherical noise-reducing structure described in Example 1.
  • the explosive was detonated and the resulting strain in' the steel structure was measured.
  • the measured strain was much less than that expected on the basis of previous experience and of design principles 4O previouslydisclosed, as shown in the table below.
  • V in pounds/ square inch, in accordance with the equation V.
  • K is an empirical constant dependent upon the explosive used
  • W is the weight of the explosive in pounds ⁇ .
  • V is-the volume of the chamber measuredin cubic-" 7 feet; a'closable access means into said chamber; "gas-venue sible strain. With the sand in: the sphere, however, the.
  • explosives-bearing assemblies can rest on the sand base.
  • a noise-reducing structure comprising a chamber Within which explosives are detonated,.said chamber having walls of sufficient mass andtensile strength to stand'an equivalent internal hydrostatic workingz pres-1 sure, P, in pounds/square inch, in. accordance with the equation 1 I W P-KV wherein K is an empirical constant dependent upon'the explosive used, W is the weight of the explosive in pounds,
  • V is the volume of the enclosed chamber measured in cubic feet; a closable access means into. said chamber; gas venting means ernanating from said chamber; and a]; of saida chamber, the height of said"segment'being about to] mass of loose granular 'solidoccupying a segment about V of vthehei'ght 'ofJsaidchamber.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Pathology (AREA)
  • Medicinal Chemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Manufacturing & Machinery (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Food Science & Technology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • Pressure Welding/Diffusion-Bonding (AREA)
  • Drilling And Exploitation, And Mining Machines And Methods (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
US165162A 1962-01-09 1962-01-09 Noise-reducing structure Expired - Lifetime US3165916A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
BE626423D BE626423A (ja) 1962-01-09
NL287590D NL287590A (ja) 1962-01-09
US165162A US3165916A (en) 1962-01-09 1962-01-09 Noise-reducing structure
GB43405/62A GB1007477A (en) 1962-01-09 1962-11-16 Noise-reducing structure
FR915884A FR1341780A (fr) 1962-01-09 1962-11-19 Structure réduisant le bruit
LU42988D LU42988A1 (ja) 1962-01-09 1963-01-09
DEP30919A DE1186384B (de) 1962-01-09 1963-01-09 Geraeuschgedaempfte Sicherheitssprengkammer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US165162A US3165916A (en) 1962-01-09 1962-01-09 Noise-reducing structure

Publications (1)

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US3165916A true US3165916A (en) 1965-01-19

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US165162A Expired - Lifetime US3165916A (en) 1962-01-09 1962-01-09 Noise-reducing structure

Country Status (6)

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US (1) US3165916A (ja)
BE (1) BE626423A (ja)
DE (1) DE1186384B (ja)
GB (1) GB1007477A (ja)
LU (1) LU42988A1 (ja)
NL (1) NL287590A (ja)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3823793A (en) * 1972-10-02 1974-07-16 Asahi Chemical Ind Semi-sealed silencer structure
US4192553A (en) * 1978-04-03 1980-03-11 Occidental Oil Shale, Inc. Method for attenuating seismic shock from detonating explosive in an in situ oil shale retort
US4474052A (en) * 1982-12-13 1984-10-02 E. I. Du Pont De Nemours And Company Laboratory barricade
US4727789A (en) * 1986-06-24 1988-03-01 T & E International, Inc. Vented suppressive shielding
US5135130A (en) * 1991-03-13 1992-08-04 Andrews James S Safety enclosure
US20090081928A1 (en) * 2005-04-08 2009-03-26 National Inst Of Adv Industrial Science And Tech. Blasting treating method

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1800234A (en) * 1929-07-01 1931-04-14 Harry C Tuttle Telephone muffler
GB373119A (en) * 1930-11-17 1932-05-17 Burgess Lab Inc C F Silencer for exhaust and other pulsating gases and vapours
US2940300A (en) * 1956-06-07 1960-06-14 Du Pont Sound reducing explosives testing facility
US2960859A (en) * 1958-03-10 1960-11-22 Du Pont Explosion-resistant structure

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1800234A (en) * 1929-07-01 1931-04-14 Harry C Tuttle Telephone muffler
GB373119A (en) * 1930-11-17 1932-05-17 Burgess Lab Inc C F Silencer for exhaust and other pulsating gases and vapours
US2940300A (en) * 1956-06-07 1960-06-14 Du Pont Sound reducing explosives testing facility
US2960859A (en) * 1958-03-10 1960-11-22 Du Pont Explosion-resistant structure

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3823793A (en) * 1972-10-02 1974-07-16 Asahi Chemical Ind Semi-sealed silencer structure
US4192553A (en) * 1978-04-03 1980-03-11 Occidental Oil Shale, Inc. Method for attenuating seismic shock from detonating explosive in an in situ oil shale retort
US4474052A (en) * 1982-12-13 1984-10-02 E. I. Du Pont De Nemours And Company Laboratory barricade
US4727789A (en) * 1986-06-24 1988-03-01 T & E International, Inc. Vented suppressive shielding
US5135130A (en) * 1991-03-13 1992-08-04 Andrews James S Safety enclosure
US20090081928A1 (en) * 2005-04-08 2009-03-26 National Inst Of Adv Industrial Science And Tech. Blasting treating method
US8006600B2 (en) * 2005-04-08 2011-08-30 Kabushiki Kaisha Kobe Seiko Sho Multiple blasting treating method

Also Published As

Publication number Publication date
BE626423A (ja)
DE1186384B (de) 1965-01-28
LU42988A1 (ja) 1963-03-29
GB1007477A (en) 1965-10-13
NL287590A (ja)

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