[Mae477]Final Project Presentation

Optimization of an ak-47
CAD 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 Kalashnikov
Image 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

Current Recoil Dampening System
Rear 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 5: Redesigned Dampening System (2of 2)
Figure 4: Redesigned Dampening System (1 of 2)

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.

DesignPhase 4:Component Modeling

Critical Components
Figure 9: Bolt Carrier
Figure 10: Butt Stock
Figure 12: AK-47 Receiver
Figure 11: AK-47 Barrel
Figure 13: Rear Recoil Spring Guide
Figure 14: Front Guide Retainer

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 AnalysisPart 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 AnalysisPart 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
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.
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.
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?

[Mae477]Final Project Presentation

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