GB2060127A

GB2060127A - A Method of and Apparatus for Improving the Ability of an Apparatus' Body to Penetrate a Solid Medium

Info

Publication number: GB2060127A
Application number: GB7930782A
Authority: GB
Original assignee: G SOJUZ Z MEK I KHIM OCHISTKE
Current assignee: G SOJUZ Z MEK I KHIM OCHISTKE
Priority date: 1979-09-05
Filing date: 1979-09-05
Publication date: 1981-04-29
Also published as: GB2060127B; SU310414A; DE2938502A1; SU217222A; SU153694A

Abstract

There is provided a method of an apparatus for improving the ability of an apparatus' body to penetrate a solid medium. The method resides in excitation of elastic deformations in a shell 1 of the apparatus (1) by applying impulses thereto. The apparatus for producing the impulses in the shell 1 comprises at least one electrically conducting element (3) and an electromagnetic inductor (2) arranged in direct proximity thereto and coupled to a power supply (4) via a switch (6) controlled by a switching unit (5) and via an electric-discharge electric power storage means (7). The method and apparatus can be used to facilitate the passage of ships through ice, in foundation engineering such as in pile driving, in tunnelling and shafting, in well drilling to facilitate sinking of casing pipes, as well as in the woodworking industry to facilitate splitting of wood. <IMAGE>

Description

SPECIFICATION Improvements in or Relating to Methods of and Apparatuses for Improving the Ability of an Apparatus' Body to Penetrate a Solid Medium The present invention relates to electric machines, and more particularly to a method of and a device for improving the ability of an apparatus' body to penetrate a solid medium.

Such a method and device can be used in shipbuilding to facilitate the passage of ships through ice, in foundation engineering to facilitate sinking of tubular piles and casing pipes, in tunnelling and shafting to facilitate the advance of tunnelling shields underground, in sinking casing pipes in well drilling, and in splitting wood in the woodworking industry.

According to one aspect of the invention, there is provided a method of improving the ability of an apparatus' body to penetrate a solid medium by exciting elastic deformations in the apparatus' shell with the aid of single mechanical impulses applied thereto, said impulses being separated by time intervals.

The mechanical impulses are preferably initiated by a pulses electromagnetic field.

At least one groups of single mechanical impulses may be applied to the apparatus' shell at a time.

A group of single mechanical impulses may be applied to the apparatus' shell at a time along a lateral section thereof.

Preferably, each single impulse has a toothed shape.

Preferably, the duration of each single mechanical impulse range is from 10-6 to 10-2 seconds and the ratio of a time interval between adjacent single mechanical impulses to the duration of each single mechanical impulse is from 100 to 10,000.

Preferably, the time intervals between two adjacent impulses is used for storing the energy of the next impulse determining the amplitude of elastic deformations in the shell, this amplitude being such that the stress created in the apparatus' shell does not exceed its cyclic strength.

According to another aspect of the invention, there is provided a device for performing the method of the invention comprising means for exciting elastic deformations connected to a power supply and including at least one electromagnetic inductor and an electrically conductive element arranged in direct proximity to the electromagnetic inductor, which is connected to the power supply via a switch controlled by a switching unit and via an electricdischarge electric power storage means.

Preferably, at least two closely spaced electromagnetic inductors are connected in series and form a coherent source of mechanical impulses connected to the electric-discharge electric power storage means via the switch.

Preferably, at least some of the electromagnetic inductors are arranged in one plane across a shell of the apparatus and are connected in series to form a coherent source of mechanical impulses coupled to the electricdischarge electric power storage means via the switch.

Preferably, the switch comprises a thyristor the control gate of which is connected to the switching unit.

The or each electromagnetic inductor preferably comprises an inductance coil accommodated in a dielectric housing provided with two lead-ins to the inductance coil.

Each lead-in preferably comprises an electrically conductive bushing accommodated in the housing of the electromagnetic inductor and connected to the inductance coil, a clamping screw, and an insulating spacer arranged on the side of the working surface of the electromagnetic inductor.

Preferably, the electromagnetic inductors are arranged on the inside of the plating of a ship's hull, near the waterline.

The electromagnetic inductors and electrically conductive elements may be arranged on the inside of a lateral surface of an icebreaking attachment secured to the hull of a ship and located at its bow.

The electromagnetic inductors may be arranged on the inside of a wall of an icebreaking attachment arranged to be located under ice at the bow of a ship, the wall facing the ice surface and being made of an electrically conductive material.

The electromagnetic inductors and electrically conductive elements may be arranged on the inside of a lateral wall of a nose cone of a mechanism for trenchless laying of pipes.

Preferably, there are arranged on the end wall of a nose cone of the mechanism of trenchless laying of pipes at least one electrically conductive element and an electromagnetic inductor connected in series with the electromagnetic inductors on the inside of the lateral wall of the nose cone.

Preferably, the electromagnetic inductors and electrically conductive elements are arranged on the inside of a cutter-mounting ring and a bearing ring of a tunnelling shield.

Preferably, the electromagnetic inductors and electrically conducting elements are arranged on the inside of a casing pipe.

Preferably, the electromagnetic inductors are attached to a shell accommodated in the casing pipe and associated therewith through a loosening ring.

Preferably, the electromagnetic inductors and electrically conducting elements are arranged on the inside of a tubular pile.

Preferably, the electromagnetic inductors and electrically conductive elements are arranged on the inside of the tapered portion of a working member of a wood splitting machine.

It is possible for the mean power consumption from an external source to be substantially reduced by storing power in the storage means during the time intervals between impulses.

Power N1 of an impulse is determined from the formula:

where N2 is the power source output, 17 is the efficiency of the device, t is the impulse duration, T is a time interval between impulses, and T 1 00sQ10,000 t Then, for example at an impulse duration of 1.10a sec, a time interval between impulses of 1 sec and a power storage means efficiency of 90%, the mean consumed power is 900 times less than the impulse power.

It is possible to increase the efficiency of penetration of an apparatus' body into a solid medium, simplify the device, and reduce its weight and size. No adverse effects are experienced by the crew of a ship wherein a preferred embodiment of the present invention is used to enhance its ability to pass through ice.

The invention will be further described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 is an electric circuit diagram of a device for improving the ability of an apparatus' body to penetrate a solid medium, with independent activation of the electromagnetic inductors, constituting a preferred embodiment of the invention; Figure 2 shows an electromagnetic inductor; Figure 3 is a sectional view taken along line Ill-Ill of Figure 2; Figure 4 is an electric circuit diagram of a device for improving the ability of an apparatus' body to penetrate a solid medium, with synchronous activation of the electromagnetic inductors integrated into groups constituting another preferred embodiment of the invention;; Figure 5 is an electric circuit diagram of a device for improving the ability of an apparatus' body to penetrate a solid medium, with synchronous activation of the electromagnetic inductors arranged in one plane across the apparatus and integrated into groups constituting yet another preferred embodiment of the invention; Figure 6 is a cross-sectional view of an apparatus' body and the grouped electromagnetic inductors; Figure 7 shows a ship's hull and electromagnetic inductors; Figure 8 shows the plating of a ship's hull and an electromagnetic inductor with an electrically conducting element in a view taken along line Vill-VIll of Figure 7; Figure 9 shows an icebreaking attachment and electromagnetic inductors; Figure 10 shows another embodiment of the icebreaking attachment and electromagnetic inductors;; Figure 11 shows a mechanism for trenchless laying of pipes underground and electromagnetic inductors with electrically conducting elements; Figure 12 shows the cutter-mounting and bearing rings of a tunnelling shield together with electromagnetic inductors and electrically conducting elements; Figure 1 3 shows a casting pipe and electromagnetic inductors with electrically conducting elements; Figure 14 shows a tubular pile and electromagnetic inductors with electrically conducting elements; and Figure 1 5 shows the working member of a wood splitting machine and electromagnetic inductors with electrically conducting elements.

A preferred method of improving the ability of an apparatus' body to penetrate a solid medium resides in excitation of elastic deformations in the apparatus' shell by applying thereto single mechanical impulses separated by time intervals.

Every single mechanical impulse has a toothed shape. Single hop compressional waves propagate through the solid medium from the points of excitation of single mechanical impulses.

The action of single-hop compressional waves upon the solid medium and the elastic deformation of the apparatus' shell result in a gap between the shell and the solid medium, which considerably reduces the friction therebetween and significantly enhances the ability of the apparatus' body to penetrate the solid medium.

The elastic deformation in an apparatus' shell can be excited by simultaneous application thereto of single mechanical impulses by groups at several points. The points of simultaneous application of single mechanical pulses of the same group must be separated by a distance in the middle whereof the total amplitude of the impulses is sufficient to force apart the solid medium and the shell, whereby a gap is formed therebetween. The points at which single mechanical pulses of adjacent groups are applied at a time must be separated by a distance in the middle of which the amplitude of a single pulse applied at each of the extreme points of adjacent groups must be sufficient to force apart the solid medium and the shell and create a gap therebetween.

The simultaneous application of impulse causes interference of the deformation waves in the apparatus' shell, which permits the zone of simultaneous action upon the solid medium to be expanded.

It is advisable to apply a group of single mechanical impulses to the apparatus' shell at a time, in one of its cross-sections.

To initiate single mechanical impulses, a fast shock-free inertial action must be exerted on the apparatus' shell without creating appreciable contact stresses therein.

This can be achieved only by employing means not involving any transfer of masses, such as impulses initiated by an electromagnetic field.

Such an action is most effective when the duration of an impulse does not exceed 10-2 seconds.

The amplitude of a single mechanical impulse and the acceleration of individual points of the apparatus' shell resulting from the action of such an impulse are sufficient to force apart the solid medium and the shell and for partial disintegration of the solid medium in the area adjacent to the shell.

The shear stresses occurring between the apparatus' shell and the solid medium due to the bending of the shell caused by the propagation therein of the deformation waves reduce the required value of acceleration of individual points of the shell. The amplitude of a single mechanical impulse, and hence the amplitude of elastic deformation, must not exceed a value at which stresses occur in the apparatus' shell, equal to the fatigue or cyclic strength of the shell material.

Therefore, the duration of a single mechanical impulse should not be less than 10-5 seconds.

In the time intervals between two impulses, the energy of the second impulse is stored with the result that the impulse power by far exceeds the mean consumed power.

The time interval between single mechanical impulses is 100 to 10,000 times longer than the duration of an impulse. A shorter time interval between impulses will not provide for a substantially lower power consumption and the required amplitude of a single mechanical impulse, while a longer interval will reduce the ability of an apparatus' body to penetrate a solid medium.

Referring now to Figure 1, a device for improving the ability of an apparatus' body to penetrate a solid medium comprises electromagnetic inductors 2 arranged near the apparatus' shell 1 and elements 3 made of highly electrically conductive material, such as copper or aluminium, arranged between the shell 1 and electromagnetic inductors 2 in direct proximity to the latter.

If the shell 1 itself is made of a highly electrically conductive material, the elements 3 may be dispensed with, and their function performed by those portions of the shell 1 which are opposite the electromagnetic inductors 2.

The electromagnetic inductors 2 are connected to a power supply 4 via switches 6 controlled by a switching unit 5 and via an electric-discharge electric power storage means 7.

The electric-discharge storage means 7 includes a capacitor 8 and a unit 9 for charging it, made up of a step-up transformer 10 and a rectifier 11.

The switches 6 may, for example, be thyristors whose control gates are connected to the switching unit 5. The switching unit 5 comprises a series arrangement including a pulse generator 12, a shift register 13, and a pulse amplifier 14.

Each electromagnetic inductor 2 is essentially an inductance coil 1 5 (Figure 2) accommodated in a housing 1 6 provided with two lead-ins 1 7 and two sockets 18 for fixtures.

The lead-ins 1 7 and the sockets 18 are arranged symmetrically with respect to the inductance coil 15, the axes passing through the centres of the sockets 18 and through the centres of the lead-ins 1 7 being mutually perpendicular.

The housing 1 6 (Figure 3) of the electromagnetic inductor 2 is essentially a panel 19 of a dielectric material, having sockets to accommodate the inductance coil 15, in combination with a dielectric case 20. The latter serves as the working surface of the electromagnetic inductor 2.

Each lead-in 1 7 comprises a bushing 21 of an electrically conducting material, located in the panel 1 9 and coupled through a connector 22 to the inductance coil 15, a clamping screw 23, and an insulating spacer 24 arranged on the side of the working surface of the electromagnetic inductor 2.

Current is supplied to the inductance coil 1 5 via a pin (not shown) introduced into a hole 25 of the bushing 21 and secured there by the clamping screw 23.

To extend the area of simultaneous action upon the shell 1 (Figure 4), at least two closely spaced electromagnetic inductors 2 should be connected in series to form a coherent source 26 of mechanical impulses, coupled to the electric discharge electric power storage means 7 via the switch 6.

Figure 5 shows an embodiment wherein, to improve the ability of an apparatus' body to penetrate a solid medium, the electromagnetic inductors 2 arranged in one plane across the apparatus' shell form a coherent source 26 (Figure 4) of mechanical impulses, connected to the electric-discharge storage means 7 via the switch 6.

Figure 6 shows a cross-section of the shell, wherein the coherent source 26 (Figure 4) is made up of four electromagnetic inductors 2 (Figure 6).

Figure 7 illustrates an embodiment intended, particularly, to facilitate the passage of a ship through ice. This embodiment is characterized by the electromagnetic inductors 2 being arranged on the inside of the plating of a ship's hull 27, near a waterline 28.

Figure 8 is a cross-sectional view of the device of Figure 7 at the point of installation of the electromagnetic inductor 2 which is secured, with the aid of a bracket 29, to framing members 30 of the hull 27. Inserted between the electromagnetic inductor 2 and the plating 31 of the hull 27 is an electrically conductive member 3.

Consider now an embodiment of the device for facilitating the passage of a ship through ice using an icebreaking attachment 32 (Fig. 9) located in the fore part of the ship's hull 27.

In this case, the electromagnetic inductors 2 are arranged on the inside of a lateral surface 33 of the attachment 32. The way in which each electromagnetic inductor 2 is secured and the arrangement of the electrically conducting elements 3 are similar to those shown in Fig. 8.

Fig. 10 shows yet another embodiment of the device for facilitating the passage of a ship through ice with the aid of the icebreaking attachment 32.

The electromagnetic inductors 2 are arranged on the inside of a wall 34 of the attachment 32 located under ice, the wall 34 facing the ice surface and being made of an electrically conductive material. The attachment 32 may accommodate several rows of electromagnetic inductors 2 which are secured to the framing members 30 of the attachment 32 with the aid of brackets 29.

Fig. 11 shows an embodiment of the device for improving the ability of an apparatus' body to penetrate a solid medium, particularly, for facilitating the penetration of a nose cone 35 of a mechanism 36 for trenchless laying of pipes into the ground.

The nose cone 35 is rigidly secured on an end of a pipe 37 the other end whereof accommodates a vibrator 38.

The electromagnetic inductors 2 and electrically conducting elements 3 are arranged on the inside of a lateral wall 39 of the nose cone 35 with the aid of a bracket 29.

At least one electromagnetic inductor 2 with an electrically conducting element 3 may be arranged on an end wall 40 of the nose cone 35, connected in series with the electromagnetic inductors 2 arranged on the lateral wall 39 of the nose cone 35.

In an alternative embodiment, the device for improving the ability of an apparatus' body to penetrate a solid medium is installed on a shield 41 (Fig. 12) used in various tunnelling applications.

The electromagnetic inductors 2 and electrically conducting elements 3 are secured, with the aid of brackets 29, on the inside of a cutter-mounting ring 42 and a bearing ring 43 of the tunnelling shield 41, along their perimeters.

Fig. 13 shows an embodiment of the device intended, in this case, to facilitate sinking of a casing pipe 44 into the ground.

The electromagnetic inductors 2 and electrically conducting elements 3 are arranged on the inside of the casing pipe 44. The latter houses a shell 45 secured to which with the aid of brackets 29 are the electromagnetic inductors 2 with electrically conducting elements 3.

The casing pipe 44 and the shell 45 are associated through a loosening ring 46.

The casing pipe 44 is provided with a removable end plate 47 which takes up the force exerted to sink the casing pipe 44 into the ground.

The embodiment of Fig. 14 is intended to facilitate sinking of tubular piles 48 into the ground.

The electromagnetic inductors 2 and electrically conducting elements 3 are attached to the inside of a tubular pile 48 with the aid of brackets 29.

The tubular pile 48 has a removable end plate 47 taking up the force exerted to sink the tubular pile 48 into the ground.

Fig. 1 5 shows an embodiment of the device for improving the ability of an apparatus' body to penetrate a solid medium, in this case facilitating penetration of a working member 49 of a wood splitting machine into wood.

The electromagnetic inductors 2 and electrically conducting elements 3 are secured, with the aid of brackets 29, on the inside of the tapered portion of the working member 49 of the wood splitting machine.

The preferred devices for improving the ability of an apparatus' body to penetrate a solid medium operate as follows.

When the power supply 4 (Figure 1) is switched on, the capacitor 8 is charged through the step-up transformer 10 and the rectifier 11. A signal applied from the switching unit 5 to the control gate of one of the thyristors turns it on, and the capacitor 8 discharges into the electromagnetic inductor 2 associated with the said thyristor. A discharge current pulse passes through the inductance coil 1 5 (Figure 3) of the electromagnetic inductor 2, initiating an electromagnetic field pulse which, in turn, induces secondary pulse current in the electrically conducting element 3 (Figure 1). When the discharge current pulse through the electromagnetic inductor 2 interacts with the pulse current induced in the electrically conducting element 3, the latter is deformed and sharply pushed away from the electromagnetic inductor 2.As a result, single-hop compressional waves are sent through the solid medium which is in contact with the apparatus' body and create a gap between the apparatus' shell and the solid medium, thereby significantly reducing the friction therebetween and facilitating the penetration of the body into the solid medium.

The use of thyristors as the switches 6 precludes heating of the electromagnetic inductors 2, which substantially extends the service life of the latter and, consequently, of the entire device.

The switching unit 5 controls the activation of the electromagnetic inductors 2 via the thyristors in a certain sequence. The generator 12 produces uninterrupted trains of current pulses applied to the ring shift register 13 and amplified by the amplifier 14.

Before the operation starts, the first position of the ring shift register 13 holds logic "1". The rest of the position hold logic "0"s, and with arrival of the first pulse from the generator 12 the thyristor associated with the first digit of the shift register 13 is turned on and the logic "1" is transferred ta the second position, so that, when the second pulse is applied from the generator 12, the thyristor associated with the second digit of the shift register 13 is turned on and the logic "1" is transferred to the next position.

In the case of synchronous operation of the electromagnetic inductors 2 (Figure 4), interference of the deformation waves in the shell 1 occurs, whereby the action upon the solid medium becomes more regular, and the area of simultaneous action upon the medium is extended.

Synchronous operation of the electromagnetic inductors 2 (Figure 6) arranged in one plane across the shell enhances the ability of the body to penetrate the solid medium to a greater extent.

The operating principle of the device mounted on the inside of the plating 31 (Figure 8) of the ship's hull 27 resides in that the elastic deformation of the plating 31 resulting from the interaction of the discharge current pulse through the electromagnetic inductor 2 with the induced pulse current through the electrically conducting element 3, as well as the single-hop compressional waves generated at the point where the elastic deformation is excited, act upon the surrounding ice and create a gap between the plating 31 of the hull 27 (Figure 7) and the ice edge. The gap minimizes the friction between the hull 27 and the ice, thereby facilitating the ship's passage through the ice field. If the exerted action is strong enough, the ice may be disintegrated, which makes the ship's passage still easier and permits freeing ships immobilized in ice.

The device arranged on the inside of the lateral surface 33 (Figure 9) of the icebreaking attachment 32 operates in a similar manner.

Using the device on the icebreaking attachment 32 is advantageous in that the latter leaves behind a lane enabling free passage of the ship.

The attachment 32 can be used to facilitate passage through ice of any type of ship.

Next, consider the operation of the device also mounted on the icebreaking attachment 32 (Figure 10), on the inside of the wall 34 facing the ice surface.

In this case, ice is broken by hydraulic impacts on its bottom surface, caused by the propagation in water of compressional waves initiated at the points of excitation of elastic deformation in the wall 34.

The principle of operation of the device mounted on the inside of the lateral wall 39 (Figure 11) of the nose cone 35 of the mechanism 36 for trenchless laying of pipes consists in that the ground surrounding the nose cone is subjected to the elastic deformation of the lateral wall 39 and single-hop compressional waves initiated at the points of excitation of said elastic deformation.

This action creates a gap between the lateral wall 39 of the nose cone 35 and the ground, thereby reducing the friction therebetween and facilitating the advance of the nose cone 35 underground with the aid of the vibrator 38.

The penetration of the nose cone 35 into the ground is also facilitated by applying single mechanical pulses to the end wall 40 thereof.

Single-hop compressional waves and the elastic deformation of the lateral wall 39 of the nose cone 35 compact the ground surrounding the latter and strengthen the surface of the resulting duct.

The device mounted on the inside of the cutter mounting ring 42 (Figure 12) and the bearing ring 43 of the tunnelling shield 41 operates similarly to that mounted on the nose cone 35 (Figure 11) of the mechanism 36 for trenchless laying of pipes.

In cases where the device is mounted on the casing pipe 44 (Figure 13) and on the tubular pile 48 (Figure 14), the gap between the surface of the casing pipe 44 (Figure 13) and the ground, as well as between the surface of the tubular pile 48 (Figure 14) and the ground, facilitates their sinking into the ground. The ground surrounding the casing pipe 44 (Figure 13) or the tubular pile 48 (Figure 14) is thus compacted.

The operation of the arrangement wherein the device is mounted on the inside of the tapered portion of the working member 49 (Figure 1 5) of the wood splitting machine is as follows. The elastic deformation of the tapered portion of the working member 49 and single-hop compressional waves create a gap between the surface of the working member 49 and wood, which provides for easier penetration of the working member 49 into the latter.

It is possible for the mean power consumption to be minimized since during the intervals between two impulses, which are 100 to 10,000 times longer than the impulses, electric power is stored in the storage means 7 to be subsequently expended in the second impulse, which also ensures more effective penetration of an apparatus' body through a solid medium.

The preferred method and device for improving the ability of an apparatus' body to penetrate a solid medium are simple, inexpensive, and the minimum number of moving parts in the device renders it highly reliable.

Claims

Claims

1. A method of improving the ability of an apparatus' body to penetrate a solid medium by exciting elastic deformations in the apparatus' shell with the aid of single mechanical impulses applied thereto, said impulses being separated by time intervals.

2. A method as claimed in claim 1, wherein the single mechanical impulses are initiated by a pulsed electro-magnetic field.

3. A method as claimed in claims 1 or 2, wherein at least one group of single mechanical impulses is applied to the apparatus' shell at a time.

4. A method as claimed in any one of claims 1 to 3, wherein a group of single mechanical impulses is applied to the apparatus' shell at a time along a lateral section thereof.

5. A method as claimed in any one of claims 1 to 4, wherein each single mechanical impulse has a toothed shape.

6. A method as claimed in any one of claims 1 to 5, wherein the duration of each single mechanical impulse is from 10-5 to 10-2 seconds and the ratio of a time interval between adjacent single mechanical impulses to the duration of each single mechanical impulse is from 100 to 10,000.

7. A method as claimed in any one of claims 1 to 6, wherein the time intervals between adjacent impulses are used for storing the energy of the next impulse determining the amplitude of elastic deformations in the shell, the amplitude being such that the stress created in the apparatus' shell does not exceed its cyclic strength.

8. A device for carrying out the method of claim 1, comprising means for exciting elastic deformations, connected to a power supply and including at least one electromagnetic inductor and an electrically conductive element arranged in direct proximity to the electromagnetic inductor which is connected to the power supply via a switch controlled by a switching unit and via an electric-discharge electric power storage means.

9. A device as claimed in claim 8, wherein at least two closely spaced electromagnetic inductors are connected in series and form a coherent source of mechanical impulses connected to the electric-discharge electric power storage means via the switch.

10. A device as claimed in claim 8, wherein at least some of the electromagnetic inductors are arranged in one plane across a shell of the apparatus and are connected in series to form a coherent source of mechanical impulses connected to the electric-discharge electric power storage means via the switch.

11. A device as claimed in any one of claims 8 to 10, wherein the switch comprises a thyristor the control gate of which is connected to the switching unit.

12. A device as claimed in any one of claims 8 to 11, wherein the or each electromagnetic inductor comprises an inductance coil accommodated in a dielectric housing provided with two lead-ins to the inductance coil.

13. A device as claimed in claim 12, wherein each lead-in comprises an electrically conductive bushing accommodated in the housing of the electromagnetic inductor and connected to the inductance coil, a clamping screw, and an insulating spacer arranged on the side of the working surface of the electromagnetic inductor.

14. A device as claimed in any one of claims 8 to 13, wherein the electromagnetic inductors are arranged on the inside of the plating of a ship's hull, near the waterline.

15. A device as claimed in any one of claims 8 to 13, wherein the electromagnetic inductors and electrically conductive elements are arranged on the inside of a lateral surface of an icebreaking attachment secured to the hull of a ship and located at its bow.

16. A device as claimed in any one of claims 8 to 13, wherein the electromagnetic inductors are arranged on the inside of a wall of an icebreaking attachment arranged to be located under ice at the bow of a ship, the wall facing the ice surface and being made of an electrically conductive material.

1 7. A device as claimed in any one of claims 8 to 13, wherein the electromagnetic inductors and electrically conductive elements are arranged on the inside of a lateral wall of a nose cone of a mechanism for trenchless laying of pipes.

1 8. A device as claimed in claim 17, wherein there are arranged on the end wall of the nose cone of the mechanism for trenchless laying of pipes at least one electrically conductive element and an electromagnetic inductor connected in series with the electromagnetic inductors arranged on the inside of the lateral wall of the nose cone.

19. A device as claimed in any one of claims 8 to 13, wherein the electromagnetic inductors and electrically conductive elements are arranged on the inside of a cutter-mounting ring and a bearing ring of a tunnelling shield.

20. A device as claimed in any one of claims 8 to 13, wherein the electromagnetic inductors and electrically conductive elements are arranged on the inside of a casing pipe.

21. A device as claimed in claim 20, wherein the electromagnetic inductors are attached to a shell accommodated in the casing pipe and associated therewith through a loosening ring.

22. A device as claimed in any one of claims 8 to 13, wherein the electromagnetic inductors and electrically conductive elements are arranged on the inside of a tubular pile.

23. A device as claimed in any one of claims 8 to 13, wherein the electromagnetic inductors and electrically conductive elements are arranged on the inside of the tapered portion of a working member of a wood splitting machine.

24. A method of improving the ability of an apparatus' body to penetrate a solid medium, substantially as hereinbefore described with reference to the accompanying drawings.

25. A device for improving the ability of an apparatus' body to penetrate a solid medium, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

New Claims or Amendments to Claims filed on 8th January 1981 Superseded Claims 1 and 2 New or Amended Claims:

1. A method of improving the ability of an apparatus' body to penetrate a solid medium exciting elastic deformations in the apparatus' shell with the aid of single mechanical impulses applied thereto, said impulses being initiated by a pulsed electro-magnetic field and being separated by time intervals.