DFM reports test specimen (tire) output forces rather than load cell reported forces, which contain machine resonance effects. DFM has been shown to expand dynamic force measurement bandwidths from the usual 50 Hz to over 1000 Hz, a twenty fold increase.

Conventional Technology (CT) pursues the maximization of mechanical resonant frequencies in order to achieve as flat a frequency response for as high a frequency range as possible before the resonant peak produces unacceptable amplification of the forces being input to the measurement system, as sensed and reported by the system load cells. Unfortunately the measurement bandwidth achievable is severely limited with this strategy. Most measurement transducers are used to only 1/10 of their resonant frequencies. Such a practice would limit High Speed Uniformity (HSU) Tire Test Machines to only about a 20 Hz bandwidth. Most tire test engineers consider measurements to 1/2 the resonant frequency of an HSU machine to be useful; however, this does amplify forces measured at such a frequency by a factor of 2X, which may not be known by the customer using such data.

At low excitation frequencies (those less than 1/10 the first resonance of the system) both CT and DFM methods produce similar results. This is generally in the 20 to 50 Hz range. Above that, the two methods produce widely divergent responses to identical inputs. The narrow bandwidth produced by CT methods used to be acceptable; however, today's automotive engineers demand measurement bandwidths that are more than ten times what CT can produce. Many engineers are now searching for bandwidth improvements, usually through FFT and FRF measurements and post processing of experimental data to compensate the resonance effects.

DFM represents the first direct measurement technique capable of such a desired bandwidth expansion. TMSI's DFM device is capable of measuring the machine resonant forces which may then be subtracted away from the load cell forces, leaving the specimen output forces for direct real-time recording during the test in real-time, rather than during a post processing session involving FFT and inverse FRF calculations. Furthemore, the process does not depend upon measurement system linearity. Looseness and nonlinear stiffness are included in the measurements and fall away in the analysis, thus dispensing with the concerns for both linearity and post processing time and inconvenience.

Output data may be selected as Load Cell, DFM, or Both for comparison purposes.

DFM now opens new opportunities for comparison of data acquired from similar test machines built at different times by different makers, and which currently produce different results due to each machine's unique resonant signature. DFM can now improve the measurement reproducibility of same-specimen output data on all such machines, making existing test systems upgradeable to meet the latest test requirements by allowing wide measurement bandwidth performance.

Why push the Current Technology limited bandwidth capability to only incrementally higher bandwidths at very high dollar costs when CT has already passed the point of diminishing returns? Significant bandwidth expansions (20X) require new methods, such as DFM, which, fortunately, costs less than CT methods and is now poised to revolutionize the world of dynamic force measurements.

Patent Approved!
Impact Tester for polymer/rubber material testing

Oop Tester

Upgrades for conformance with FMVSS 139

The proposed High Speed and Endurance tests would replace the current High Speed and Endurance tests in FMVSS No. 109, New Pneumatic Tires - Passenger Cars, 49 CFR 571.109, with a more stringent combination of testing parameters (ambient temperature, load, inflation pressure, and duration). Most significantly, the proposed High Speed test specifies test speeds (140, 150, and 160 km/h (88, 94, and 100 mph)) that are substantially higher than those currently specified in FMVSS No. 109 (120, 128, and 136 km/h (75, 80, and 85 mph)). Likewise, the proposed Endurance Test specifies a test speed 50% faster (120 km/h (75 mph)) than that currently specified in FMVSS No. 109 (80 km/h (50 mph)), as well as duration 6 hours longer (40 hours total) than that currently specified in FMVSS No. 109 (34 hours total). At the specified test speed (120 km/h), the Proposed Endurance Test distance (4800 km) is almost double the distance accumulated than under the current Endurance Test (2720 km at 80 kh/h). These new testing parameters are based on NHTSA's activities undertaken in response to the TREAD Act, including extensive agency testing, data gathering and analyses, as well as agency review of other existing international, industry and National standards and proposals, and submissions by the public.

•  Upgrades available for FMVSS-139
•  New machines for expanding capacity needed to comply with FMVSS-139
•  Low cost TTM-1 for FMVSS-139
•  Add modular add-on options to a basic FMVSS-139 Tire Test Machine
•  Convert your old Dead Weight (hanging weight)(Bureau of Standards) Tire Durability Testing Machine with hydraulic servo load systems, electric screw type loading systems, or with new automated control with Digital PID to comply with the new demands of FMVSS-139

TMSI is combining over 35 years of Tire Testing Experience from products formerly manufactured by Akron Standard, with the latest innovations from TMSI to produce the highest value tire testing equipment available in the industry.

High Speed Tire Uniformity Machines

Modular, Compact & Retrofittable Options