OPTIMIZATION OF AN AK-47CAD Applications

December 16th, 2010

Presented By: Christopher N. Berry

History of the AK-47

The AK-47 was developed by Mikhail Kalashnikov between 1941 and 1947.

75+ million rifles have been manufactured since its inception.

Kalashnikov has never profited from weapon sales.

Figure 1: Picture of a Mikhail KalashnikovImage source:

http://en.academic.ru/dic.nsf/enwiki/11815

DesignPhase 1:

Product Evaluation

What are the Strengths?

Extremely reliable.

Very low cost.

Easy to manufacture.

Low maintenance.

What are the Weaknesses?

1) Firing Inaccuracy.

Video Source 1: http://www.youtube.com/v/xeeeFxA_9nA

What are the Weaknesses? (Cont.)2) Weapon Handling

Video Source 2: http://www.youtube.com/v/QVpents7XbA&feature=related

Design Goals

Increase firing accuracy.

Increase weapon handling.

Increase weapon durability

DesignPhase 2:

Preliminary Design/Survey

Product Comparison

M16 vs. AK-47

M16 has a heavier and thicker barrel.

M16 has a compact design.

M16 has lower recoil due to “buffer piston”, as well as a smaller round.

Product Comparison (Cont.)

M16 Weapon Handling

Video Source 3: http://www.youtube.com/v/xBZWCHWqwGc&feature=related

DesignPhase 3:

Project Management andIdea Generation

Project Time Line

Figure 2: AK-47 Redesign Gantt Chart

Click icon to add picture

Current Recoil Dampening SystemRear Recoil Spring Guide: consists of a mount, 2 guide bars, a spring, and a “front guide retainer”.

Figure 3: Picture of a Rear Recoil Spring Guide.Image source:

http://www.monstermarketplace.com/firearms-and-

firearm-supplies/romanian-ak47-recoil-spring-assembly-ak-ro02

Alternative Design Sketches (1 of 2)Proposed Dampening System to reduce recoil and increase weapon handling.

Figure 4: Redesigned Dampening System (1 of 2)

Figure 5: Redesigned Dampening System (2of 2)

Click icon to add picture

Current Barrel and Receiver Assembly

Figure 6: AK-47 Barrel and Receiver

Alternative Design Sketches (2 of 2)Component Redesign to reduce system flexibility and increase weapon accuracy.

Figure 7: Redesigned Dampening System (1 of 2)

Figure 8: Redesigned Dampening System (2 of 2)

DesignPhase 4:

Component Modeling

Critical Components

Figure 11: AK-47 Barrel

Figure 13: Rear Recoil Spring Guide

Figure 12: AK-47 Receiver

Figure 14: Front Guide Retainer

Figure 9: Bolt Carrier Figure 10: Butt Stock

Critical Sub-Assembly

Figure 15: Exterior of Receiver Sub-Assembly

Figure 16: Interior of Receiver Sub-Assembly

Figure 17a: AK-47 Assembly Top View

Figure 17b: AK-47 Assembly Side View Figure 17c: AK-47 Assembly Front View

Figure 17d: AK-47 Assembly Full View

Full Assembly

Full Assembly (Cont.)

Figure 18: Exploded Full Assembly Figure 19: Bill of Materials

DesignPhase 5:

Engineering Analysis

Part 1: Current Components

Increase Firing AccuracyBarrel Analysis (Current)

Performed a frequency analysis on the barrel.

Applied rough mesh

Created joint at receiver connection.

Applied continuous load of 500 lb-f on the end of the barrel.

Figure 20: Mesh and force application on current barrel.

Increase Firing Accuracy (Cont.)Barrel Analysis (Current) Results

Figure 21a: Displacement diagram for current barrel.

Figure 21b: Stress diagram for current barrel.

Increase Firing Accuracy (Cont.) Receiver Analysis (Current)

Performed a frequency analysis on receiver.

Applied rough mesh Created joint at

barrel and full butt stock connection.

Applied continuous load of 500 lb-f along the base interior side.

Figure 23: Mesh and force application on current barrel.

Increase Firing Accuracy (Cont.)Receiver Analysis (Current) Results

Figure 24a: Displacement diagram for current receiver.

Figure 24b: Stress diagram for current receiver.

Increase Weapon HandlingBolt Carrier Motion Analysis (Current)

Performed motion analysis on bolt carrier.

Applied a Recoil Force of 77,992 lb-f on the bolt carrier.

The spring is given a constant of 7.5lb-in.

Damping Value of 3.7lbf/(in/s).

Video Source 4: http://www.youtube.com/watch?v=6o4MZ38d9NI

Increase Weapon Handling (Cont.)Bolt Carrier Motion Analysis (Current) Results

X-Position, Velocity and Acceleration of the “front guide retainer.”

Graph shows bolt carrier coming to rest after initial firing of bullet.

Figure 25: Motion Parameters for front guide retainer.

DesignPhase 5:

Engineering Analysis

Part 2: Redesigned Components

Redesigned Components

Receiver wall thickness doubled from 0.05 inches to 0.1 inches.

Barrel outer diameter uniformly increased by 15%.

Figure 26a: Redesigned Receiver.

Figure 26b: Redesigned Barrel.

Increase Firing AccuracyBarrel Analysis (Modified)

Performed a frequency analysis on the barrel.

Applied rough mesh

Created joint at receiver connection.

Applied continuous load of 500 lb-f on the end of the barrel.

Figure 27: Mesh and force application on modified barrel.

Increase Firing Accuracy (Cont.)Barrel Analysis (Modified) Results

Figure 28a: Displacement diagram for modified barrel.

Figure 28b: Stress diagram for modified barrel.

Increase Firing Accuracy (Cont.) Receiver Analysis (Modified)

Performed a frequency analysis on receiver.

Applied rough mesh Created joint at

barrel and full butt stock connection.

Applied continuous load of 500 lb-f along the base interior side.

Figure 29: Mesh and force application on modern barrel.

Increase Firing Accuracy (Cont.)Receiver Analysis (Modified) Results

Figure 30a: Displacement diagram for modified receiver.

Figure 30b: Stress diagram for modified receiver.

Increase Weapon HandlingBolt Carrier Motion Analysis (Modified)

Added a polyurethane dampener to reduce the recoil force.

Attached dampener along rear recoil spring guide.

Figure 31a: Polyurethane (11671) dampener.

Figure 31b: Attached dampener to rear recoil spring guide.

Increase Weapon Handling (Cont.)Bolt Carrier Motion Analysis (Modified) Results

X-Position, Velocity and Acceleration of the “front guide retainer.”

Graph shows bolt carrier speed was dramatically reduced due to dampener.

Figure 32: Motion Parameters for modified front guide retainer..

Results

Increased Firing Accuracy

AK-47 Rifle BarrelOriginal Revised

( in) (in)1.56 1.003

15% increase of outer diameter for barrel yields 36% displacement reduction.

28% reduction of max displacement for receiver with 50% increase in wall thickness.

Barrel movement further reduced, which means bullet will exit with straighter trajectory and increase accuracy.

AK-47 ReceiverOriginal Revised

( in) (in)2.68E-06 7.6e_7

Figure 33a: Displacement results chart.

Figure 33b: Displacement results chart.

Increase Weapon Handling

System is dramatically slowed down after contacting dampener.

Rest time is increased by 20.6% for modified system.

Weapon handling is directly increased due to recoil reduction.

Figure 34: Motion Parameters result comparisson chart.

Increase Durability

15% increase of outer diameter for barrel yields 37% max stress reduction.

50% increase of receiver wall thickness results in a 52.3% decrease in max stress.

This shows less stress in system, therefore system is more durable, which will in turn increase accuracy.

AK-47 ReceiverOriginal Revised

( in) (in)2.68E-06 7.6e_7

AK-47 Rifle BarrelOriginal Revised

(kpsi) (kpsi)217 137

Figure 35a: Stress results chart.

Figure 35b: Stress results chart.

Discussion

Design Problems

Simulating Recoil Difficult to know dampening coefficient and spring

coefficient without complex disassembly of AK-47. Configured settings by trial and error based upon known system behavior.

Motion Simulation Very difficult to analyze a system with multiple

components being accounted for. Resolved this by suppressing unnecessary

components (Trigger assembly, bolt, bolt pin, etc.).

Questions?