Ammunition Dynamics in Rapid Fire Guns using MSC …web.mscsoftware.com/events/vpd2006/na/presentations/60.pdf · General Dynamics Armament and Technical Products. 2 ... Ammunition

MSC.Software VPD Conference | July 17-19, 2006 | Huntington Beach, California

Ammunition Dynamics in Rapid Fire Guns using MSC Adams®

Jerry Browne

General Dynamics Armament and Technical Products

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AbstractAmmunition Dynamics in Rapid Fire Guns Using MSC AdamsPresentation Number 2006-60

Jerry BrowneGeneral Dynamics Armament and Technical Products128 Lakeside Avenue, Burlington, Vermont, 05401-4985Phone: 802-657-6345, Fax: 802-657-6699, email: [email protected]

Multi-barrel Guns are designed for high rate of fire. High rate of fire requires automated ammunition feed and spent case extraction. The dynamics of an automated ammunition feed system at the gun interface is modeled using Adams. Items included in the model are the following (1) full round of ammunition transported into a multi-barrel gun via feed sprockets, (2) rounds directed by guiding surfaces and sprockets rotating with defined motions, (3) round pick-up and seating in its firing position by gun bolt and (4) extraction of spent case from the gun bolt and rotor along defined path.

The Adams model is used to determine the effects of changes in ammunition inertial properties, ammunition surface geometry, guide surface geometry and feed rate on the round hand-off process. The model employs rigid bodies, some of which are constrained to defined motion, and others that are free bodies moving only through contact with guide surfaces and these constrained motion bodies.

Shell for all bodies are incorporated and used to generate three dimensional contacting surfaces. These contacting surfaces provide narrow passages with very little room for round path error. It is essential that the hand-off process be well timed and round dynamics be well defined to ensure proper functioning of the gun.

This presentation will demonstrate both the capabilities of IDEAS/Adams in simulating such a high speed process, and illustrate where additional capabilities would be an asset to high-speed dynamic

processes containing guiding surface contact.

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Agenda

• Introduction - Project• Methodology• Details• Results• Lessons Learned• Follow on Work

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Introduction

• Multi-barrel Guns are designed for high rate of fire. High rate of fire requires automated ammunition handling.

• IDEAS® & MSC Adams® used to model ammunition hand-off dynamics at the gun interface.

• Features of the process are provided in this document

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Methodology

• Create assembly of parts in IDEAS®• Include essential only• Locate parts in the initial configuration • Subdivide large parts

• Convert assembly to multi-body rigid model using Mechanism Simulation• Generate rigid bodies & essential markers• Create constraints, splines, forces and motions

• Complete modeling in Adams®

• Generate body-to-body contacts• Run simulation and post process results

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Details

• Modeled Items:• Ammunition (Rounds) transport into a multi-barrel gun via Guides and

Sprockets with defined motion

• Gun Bolt pick-up, seating and transport of round to and from its firing position

• Unloading of spent case from Gun Bolt, and its transport return to storage container via Sprockets and Guides

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Details - IDEAS® Model

• Objective:

• Create assembly of parts to represent ammunition passage through gun, feed and unload systems

• Parts placement in assembly• Parts material properties defined • Coordinate systems for joints

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Details - IDEAS® Model

Feed Guides & Sprockets Unload Guides & Sprockets

AmmunitionGun Bolt

Gun Rotor

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Details – MSC Adams® Model

• Objective:• Understand round hand-off process & influences: • Ammunition inertial properties• Ammunition surface geometry • Guide surface geometry • Feed rate

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Body-to-Body Contact between Ammunition and other Parts

3-axis Translational Motion: Gun Housing

Rotational Motion: Rotor, Feed Sprockets, Unload Sprockets

Translational Motion: Gun Bolts

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• Model contains• Rigid bodies with motion constraints• Free bodies moving through contact with constrained-motion

bodies and guide surfaces• Shell for all bodies used to generate three dimensional

contacting surfaces.• Contacting surfaces provide narrow passages; little room for

round path error. • Hand-off process must be well timed and round dynamics be well

defined.

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Round Path

Gun Bolt Path

Feed Sprockets Unload Sprockets

Inner Guides

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Results – MSC Adams® Model

Animation 1 – Two Round Unloading (auto or double-click to play)

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Results – MSC Adams® Model

Animation 2 – Two Round Unloading (auto or double-click to play)

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Lessons Learned

• Surface details significantly influence body-to-body contact. Partitioning solid model surface increases realistic surface contacts

• Contact with thin shell objects difficult to maintain (large aspect ratio objects slips through its contact.

• Solution for round ramming into barrel requires extreme care to obtain solution

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Follow-on work / Wish List

• Replace some rigid guides by their finite element models• Rigid-to-Fem or Fem-to-Fem contact difficult to model with moving

contact.

• Wish List• Provide simplified method of generating body to body contact between

two finite element parts or rigid-to-Fem part

Documents

Ammunition Dynamics in Rapid Fire Guns using MSC …web.mscsoftware.com/events/vpd2006/na/presentations/60.pdf · General Dynamics Armament and Technical Products. 2 ... Ammunition