Dimensional Metrology

Dimensional Metrology Program

Steve Phillips

Program Manager

DOD Body Armor Study

A high value measurement analysis

using MEL expertise in:

• Coordinate Metrology

• Measurement Uncertainty

• Laser Scanners

Dimensional Metrology

The Problem: The Inspector General of the Pentagon and the Government Accountability Office issue extensive reports on problems in Army body armor testing

GAO Finds Flaws in Army Body Armor TestsCBS News: October 16, 2009

GAO finds mistakes in Army test of body armor Associated Press: October 18, 2009

Army recalls 16,000 body armor sets amid testing disputeCNN: January 29, 2009

Audit: Army unsure of some body armor safetyUSA Today: April 2, 2008

Dimensional Metrology

The Issue MEL Addressed: New measurement technology has unknown accuracy when used for body armor tests

The Fallout: The next phase of body armor production is delayed until the issue is resolved affecting up to $8B in contracts

Dimensional Metrology

The Measurement Problem: GAO states that the new measurement technology using an articulating arm CMM with a laser scanner has unknown accuracy when used for body armor tests

(left) The articulating arm CMM equipped with a laser scanner probe(middle) Scanning the pre-impact contoured clay surface. (right) Body armor attached to contoured clay surface

Dimensional Metrology

The measurand is to determine the depth of the impact deformation relative to the pre-impact surface

(left) Projectile impact in body armor(middle) Scanning the post-impact deformation in the clay surface. (right) Detail of the complicated nature of the impact deformation

Dimensional Metrology

DOD contracted NIST to resolve:

1. Measurand stability

2. Measurement accuracy

3. Data reporting

4. Measurement reliability

5. Test conditions

Dimensional Metrology

Some of the “depth” measurands

Pre-impact surface

Post-impact surface

Point of Aim

REFERENCEDIRECTION

Dimensional Metrology

Measurement Accuracy

Dimensional Metrology

Conclusion:

NIST issues Final Report (2-17-2010) resolving measurement related issues

Dimensional Metrology

Q & A

Disclaimer:

Data on commercial products are only provided for the sake of describing experimental results. NIST does not endorse or recommend any commercial products or imply that this equipment is the best for any particular application.