1. Barrel Vibration and Accuracy October 22, 2009– Slide 1 The Effect of Barrel Damping, Stiffness and Mass Tuning on Benchrest Rifle Accuracy Structured Research - Interim Report University of Louisville Nicholas Tackett

2. Barrel Vibration and Accuracy October 22, 2009– Slide 2 Agenda 1.Project Outline 2.Background Information 3.Model Development 4.Model Analysis 5.Future Work

3. Barrel Vibration and Accuracy October 22, 2009– Slide 3 Project Outline 1.Develop an accurate model of a rifle. 2.Determine how vibration affects trajectory. 3.Model mass tuners to delay barrel vibrations. 4.Use finite element methods to evaluate design.

4. Barrel Vibration and Accuracy October 22, 2009– Slide 4 Background Information 1.Main goal is to be able to hit the bull’s-eye of a target consistently. 2.Record for a five shot grouping is less than 0.1’’ at 200 yards. [1] 3.Previous research focused on the smaller of two types of ammunition used. [2] 4.Previous research found that a variable mass tuner did affect rifle’s accuracy. [2] [1] - http://nbrsa.org/nbrsa-short-range-records#attachmentshttp://nbrsa.org/nbrsa-short-range-records#attachments [2] - http://varmintal.com/aeste.htmhttp://varmintal.com/aeste.htm

5. Barrel Vibration and Accuracy October 22, 2009– Slide 5 Model Development Simplified model of an actual rifle.

6. Barrel Vibration and Accuracy October 22, 2009– Slide 6 Model Analysis 1.Models will be evaluated using LS-DYNA package of ANSYS. 2.Simulated load will be the pressure expansion from burning powder. Figure 1. 3.Constraints will only be applied in the vertical direction. 4.Plots of the muzzle’s angle change will be made. Figure 2.

7. Barrel Vibration and Accuracy October 22, 2009– Slide 7 Model Analysis Figure 1. General Pressure Curve for N-133 Powder. http://varmintal.com/aeste.htm

8. Barrel Vibration and Accuracy October 22, 2009– Slide 8 Model Analysis 1.Models will be evaluated using LS-DYNA package of ANSYS. 2.Simulated load will be the pressure expansion from burning powder. Figure 1. 3.Constraints will only be applied in the vertical direction. 4.Plots of the muzzle’s angle change will be made. Figure 2.

9. Barrel Vibration and Accuracy October 22, 2009– Slide 9 Model Analysis Figure 1. General Barrel Vibration, with and without Mass Tuner. http://varmintal.com/aeste.htm

10. Barrel Vibration and Accuracy October 22, 2009– Slide 10 Future Work 1.Model Analysis Import solid models to LS-DYNA. Apply appropriate loads and constraints. Generate muzzle angle v. time data. 2.Data Processing Use Recreational Software, Inc. tools to generate pressure curve. Obtain muzzle velocities for a significant number of rounds. Use generated plots and known bullet speeds to find launch angle of bullet. Use external ballistics calculator to project bullet’s impact point.

11. Barrel Vibration and Accuracy October 22, 2009– Slide 11 Questions?