WE HAVE IGNITION
created a team with experts from across the U.S. Army Combat Capabilities Develop- ment Command (DEVCOM) Armaments Center, DEVCOM Army Research Labo- ratory, the Program Manager for Combat Ammunition Systems and the Army Test and Evaluation Command in an effort to assemble a group of engineers and statisti- cians from multiple artillery competencies, each representing a piece of the cannon- ammunition interface. Once assembled, the work began.
DIGITAL SYSTEM DESIGN TOOL Te diverse team held many discussions and brainstorming sessions to develop a plan of action. Trough collaborative discussions and experiences, the team agreed that the focus of this cannon design should be on ignition, with the premise that improved ignition will create an environment to develop future complex systems that can survive in the battlefield with higher reliability.
With the focus established, the team then defined “improved ignition.” For this effort, the team defined the phrase as a reduction in the rate of change in pressur- ization over the change in time during the ballistic cycle as well as a reduction in pres- sure waves while maintaining established projectile muzzle velocity performance.
Tis project employed the statistical tool called design of experiments. Tis is a novel approach in the design of both the cannon and the propelling charge as well as the interface between them.
An extensive design of experiments was used in conjunction with other statistical modeling tools and existing interior ballis- tic models. In addition to the models, the team obtained test data from a ballistic simulator, which is a test apparatus that ignites propellant in a clear tube to allow for the visual analysis of the ignition phase of the ballistic cycle. Te ballistic simu- lator fixture is also equipped with the
capability to capture pressure traces at both the simulated breech end and the simulated projectile base locations. Using such tools and incorporating them into the design of experiment process makes it possible to identify the strong relation- ships among different factors—or, in other words, to mathematically understand and identify how different features of the cannon design affect different features of the propulsion design, and vice versa.
Identifying all these features, also known as “factors,” was the backbone of this process. After the team defined all the factors (e.g., dimensions, weights and rates, as well as other specifications and characteristics) between the cannon and propulsion systems, a range of values for each factor was determined. From this, the team was able to produce thou- sands of different design configurations. Ten, using the interior ballistic model- ing tools, the team was able to predict the performance of each configuration. Te statistical analysis combined all these predictions to produce a surrogate model, later named the Digital System Design Tool (DSDT), which enabled the rank- ing of all the factors in influential order.
A system engineering tool called “value functions,” which provides a way to define acceptability and to rank the importance of different characteristics, was
then
applied, giving the team the criteria neces- sary to determine configurations that will improve ignition as well as configurations that do not.
DESIGN OF EXPERIMENTS
Overview of the design of experiments process created to design the cannon and propelling charge, and the interface between the two. (Graphic by Peter Harvey, PD TAS)
Validation is the key to any modeling effort, as it gives the effort credibility by confirming outputs through actual test- ing. Validation also enables modeling enhancements that will increase its fidelity. For the DSDT effort, ballistic simulator testing was the best tool available to assess ignition. Te DSDT provided thousands
82 Army AL&T Magazine Summer 2024
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148
