The document summarizes an optimization project for an AK-47 rifle through CAD modeling and engineering analysis. The goals were to increase firing accuracy, weapon handling, and durability. Through redesigning components like thickening the receiver wall and enlarging the barrel diameter, and adding a polyurethane dampener, analysis showed reductions in stress and displacement, indicating improved accuracy, reduced recoil, and increased durability.

1. Optimization of an ak-47 CAD Applications December 16th, 2010 Presented By: Christopher N. Berry

2. 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

3. DesignPhase 1:Product Evaluation

4. What are the Strengths? Extremely reliable. Very low cost. Easy to manufacture. Low maintenance.

5. What are the Weaknesses? 1) Firing Inaccuracy. Video Source 1: http://www.youtube.com/v/xeeeFxA_9nA

6. What are the Weaknesses? (Cont.) 2) Weapon Handling Video Source 2: http://www.youtube.com/v/QVpents7XbA&feature=related

7. Design Goals Increase firing accuracy. Increase weapon handling. Increase weapon durability

8. DesignPhase 2:Preliminary Design/Survey

9. 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.

10. Product Comparison (Cont.) M16 Weapon Handling Video Source 3: http://www.youtube.com/v/xBZWCHWqwGc&feature=related

11. DesignPhase 3:Project Management andIdea Generation

12. Project Time Line Figure 2: AK-47 Redesign Gantt Chart

13. 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

14. 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)

15. Current Barrel and Receiver Assembly Figure 6: AK-47 Barrel and Receiver

16. 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)

17. DesignPhase 4:Component Modeling

18. 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

19. Critical Sub-Assembly Figure 15: Exterior of Receiver Sub-Assembly Figure 16: Interior of Receiver Sub-Assembly

20. 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

21. Full Assembly (Cont.) Figure 18: Exploded Full Assembly Figure 19: Bill of Materials

22. DesignPhase 5:Engineering AnalysisPart 1: Current Components

23. 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.

24. Increase Firing Accuracy (Cont.)Barrel Analysis (Current) Results Figure 21a: Displacement diagram for current barrel. Figure 21b: Stress diagram for current barrel.

25. 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.

26. Increase Firing Accuracy (Cont.)Receiver Analysis (Current) Results Figure 24a: Displacement diagram for current receiver. Figure 24b: Stress diagram for current receiver.

27. 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

28. 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.

29. DesignPhase 5:Engineering AnalysisPart 2: Redesigned Components

30. 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.

31. 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.

32. Increase Firing Accuracy (Cont.)Barrel Analysis (Modified) Results Figure 28a: Displacement diagram for modified barrel. Figure 28b: Stress diagram for modified barrel.

33. 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.

34. Increase Firing Accuracy (Cont.)Receiver Analysis (Modified) Results Figure 30a: Displacement diagram for modified receiver. Figure 30b: Stress diagram for modified receiver.

35. 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.

36. 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..

37. Results

38. 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.

39. 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.

40. 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.

41. Discussion

42. 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.).

43. Questions?