SAWE Technical Papers

@inproceedings{3612,

title = {3612. Measurement of the Inertia Tensor - A Review},

author = {Giorgio Previati and M. Gobbi and G. Mastinu},

url = {https://www.sawe.org/product/paper-3612},

year  = {2014},

date = {2014-05-01},

booktitle = {73rd Annual Conference, Long Beach, California},

pages = {23},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Long Beach, California},

abstract = {This paper is focused on the measurement of the full inertia tensor of a rigid body. In the literature, many papers can be found addressing this problem. Basically, two different measurement approaches are used. 

In the first approach, different moments of inertia around different axes are measured and then the inertia tensor is reconstructed from these measurements. In this case, the measurement of the moment of inertia around a given axis can be performed with very high accuracy. In the reconstruction of the inertia tensor is, however, some uncertainty is introduced due to the positioning of the rotation axes with respect to the body. 

The second measurement approach involves the realization of a test rig able to apply a complex motion to the body under investigation. By a proper measurement of the motion and a suitable mathematical procedure, is possible to derive all the components components of the inertia tensor from a single experiment. Sometimes, the motion is reduced to a vibration of small amplitude and the inertia tensor is derived from a modal analysis. 

The experimental techniques referring to such two strategies are presented and the underlying theoretical and mathematical aspects involved are discussed.},

keywords = {05. Inertia Calculations, 06. Inertia Measurements, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3500,

title = {3500. Technical Feasibility Study for the Measurement of the Inertia Properties of an Aircraft},

author = {Giorgio Previati and G. Mastinu and M. Gobbi},

url = {https://www.sawe.org/product/paper-3500},

year  = {2010},

date = {2010-05-01},

booktitle = {69th Annual Conference, Virginia Beach, Virginia},

pages = {21},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Virginia Beach, Virginia},

abstract = {A feasibility study for the measurement of the inertia properties of a full-scale aircraft is presented. The employment of the InTenso+ system developed at Politecnico di Milano is discussed referring to the measurement of the inertia properties of a fighter aircraft. Preliminarily, the InTenso+ system is introduced to highlight its basic features. Then, referring to the addressed non standard aeronautic application, the accuracy of the measurement method is investigated. Both analytical and numerical analyses are presented to estimate the uncertainties of the measurement method. The measurement of the inertia properties of a full scale aircraft is technically feasible within the accuracy quantified in this report. Economic and financial issues are not critical, being the InTenso+ system very simple and consequently inexpensive (the implementation costs are not given in this paper as they depend on the customization of the system). The main result of this paper is that, maybe for the first time since the beginning of aeronautical engineering, the measurement of the full inertia tensor and of the location of the centre of gravity of aircrafts appears feasible in a simple way. Such a measurement can be performed by using the InTenso+ system.},

keywords = {03. Center Of Gravity, 06. Inertia Measurements, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3465,

title = {3465. Advances on Inertia Tensor and Centre of Gravity Measurement: The Intenso+ System},

author = {Giorgio Previati and Giamiero Mastinu and Massimiliano Gobbi},

url = {https://www.sawe.org/product/paper-3465},

year  = {2009},

date = {2009-05-01},

booktitle = {68th Annual Conference, Wichita, Kansas},

pages = {20},

address = {Wichita, Kansas},

abstract = {The accurate and quick measurement of the inertia properties of rigid bodies is dealt with in the paper. Firstly, a survey of the current measurement/identification methods is given, highlighting the expected accuracy and practical implementation issues for each method. The test rigs developed at the Politecnico di Milano (Technical University of Milan) for the identification of the inertia properties are 

presented. These test rigs (named InTenso and InTensino, being InTensino just a scaled version of the InTenso system) have been in use since 2001 for the identification of the inertia tensor of rigid bodies ranging from 50 to 3500 kg. Such test rigs are multi-cable/rod pendulums carrying the body under identification. The cables can be configured in order to let the body swing around (approximately) its 

centre of mass. From the recorded motion the inertia tensor is identified by a proper numerical procedure. 

In the second part of the paper, the attention is focused on a new implementation of the InTenso and 

InTensino test rigs. In such a new implementation, the new test rigs (InTenso+ and InTensino+) are able to identify both the inertia tensor and the centre of gravity location during one single experiment. Due to the very simple hardware and instrumentation involved, the very short measurement time and the 

relatively high accuracy, these test rigs seem suitable for commercial development.},

keywords = {03. Center Of Gravity, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{3466,

title = {3466. Feasibility Study for the Measurement of the Inertia Properties of Huge Bodies},

author = {Giorgio Previati and Giamiero Mastinu and Massimiliano Gobbi},

url = {https://www.sawe.org/product/paper-3466},

year  = {2009},

date = {2009-05-01},

booktitle = {68th Annual Conference, Wichita, Kansas},

pages = {18},

address = {Wichita, Kansas},

abstract = {The identification of the inertial properties of complex bodies is a well discussed issue. The importance of the accurate knowledge of these quantities for the correct simulation of mechanical systems has been recognized by many authors. In the literature, many different methods and often complicated test rigs have been proposed. In most cases these test rigs are able to identify the inertia properties of compact bodies and in only few cases body as large as ground vehicles can be measured. At the best knowledge of the authors methods for the measurement of the inertia tensor of very large rigid bodies such as airplanes and ships have not been yet proposed. 

In this paper the feasibility of such measurements is discussed. The proposed method is based on the test rig for the measurement of the inertial properties of car vehicle size rigid bodies developed at the Politecnico di Milano (Technical University of Milan). This test rig is basically a three or four bar pendulums carrying the body under investigation. The body is made rotate around three axes passing nearby the body centre of gravity and the resulting highly non linear motion is recorded. By a proper identification procedure, the centre of gravity location and the inertia tensor can be assessed with a single experimental test. The absence of any dynamic excitation of the motion of the system makes this method suitable for the very large bodies discussed here.},

keywords = {03. Center Of Gravity, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1634,

title = {1634. Mass Properties and Automotive Longitudinal Acceleration},

author = {B P Wiegand},

url = {https://www.sawe.org/product/paper-1634},

year  = {1984},

date = {1984-05-01},

urldate = {1984-05-01},

booktitle = {43rd Annual Conference, Atlanta, Georgia, May 21-23},

pages = {58},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Atlanta, Georgia},

abstract = {Automotive longitudinal acceleration is dependent upon a large number of interconnected parameters, some of the most important of which are mass properties. The purpose of this paper is to explore the individual mass property effects. 

The approach taken to achieve this purpose was to decouple the parameters by means of a computer simulation of an automotive acceleration 'run'. Each individual mass property parameter was then varied over a wide range while all other parameters were held constant. The acceleration results so obtained were plotted, and the conclusions were drawn from the behavior thus exhibited. 

Several conclusions have been drawn from this effort. First, the effects of a mass property parameter variation are not necessarily constant over the entire speed range. For instance, increasing weight tends to cause an almost linear increase in the elapsed times for the lower speed ranges, but the higher speed ranges exhibit even greater time increases in an almost parabolic relationship. This is a matter of the increased rolling resistance associated with greater weight making itself felt at the higher speeds. 

The longitudinal center of gravity (kg) and the vertical center of gravity (vcg) both affect acceleration through traction. If the situation is not traction critical then cg relocation can be of no help in obtaining better acceleration. When a situation is traction critical then acceleration is much more sensitive to change in kg then in vcg. 

Increasing the vertical center of gravity tends to benefit the acceleration of rear wheel drive vehicles. For rear wheel drive vehicles the vcg generates increased traction through weight transfer. In the case of front wheel drive, the vcg can have no beneficial effect as the weight transfer is in the direction away from the drive axle; minimizing the vcg becomes the priority. Due to the effect of weight transfer, a front wheel drive vehicle will always be inferior in acceleration to a rear wheel drive vehicle if everything else is equal and the propulsive capability is great enough. 

In general, a rotational mass is disproportionately detrimental to acceleration because it has to be accelerated both rotationally and translationally. The greatest return for the effort involved in mass reduction can be obtained from a reduction in rotational masses. 

The engine rotational masses, other than the flywheel, represent a special case outside the scope of this paper. Vehicle characteristics and use demand a certain minimal rotational inertia for the flywheel to counteract engine stall-out tendencies at the onset of acceleration and to ensure smooth engine operation. In fact, a higher flywheel inertia can produce an initially quicker vehicle. This initial response has to be considered against the detrimental longer-term effects of accelerating a large flywheel inertia throughout the speed range. Flywheel design involves a high degree of compromise. 

Rev A - 2023},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1400,

title = {1400. The Significance of Weight on Light Trucks},

author = {G R Moulton},

url = {https://www.sawe.org/product/paper-1400},

year  = {1981},

date = {1981-05-01},

booktitle = {40th Annual Conference, Dayton, Ohio, May 4-7},

pages = {7},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Dayton, Ohio},

abstract = {This paper is an overview of the effects of customer requirements; Federal Safety, Exhaust Emission, Fuel Economy and Excise Tax requirements; vehicle complexity on light truck weights; and a brief outline of light truck weight control at Ford Motor Company. 

Light trucks include pickups and vans; derivative vehicles such as Blazers, Broncos and Suburbans based on pickups and Club Wagons based on vans; and pickups that are passenger car derivatives such as the VW Rabbit pickup. The Ford pickup is the largest selling vehicle in the world with the Chevrolet pickup selling only a few thousand units less annually.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1369,

title = {1369. The Effect of Government Regulations on Vehicle Weight},

author = {M H Allmacher},

url = {https://www.sawe.org/product/paper-1369},

year  = {1980},

date = {1980-05-01},

booktitle = {39th Annual Conference, St. Louis, Missouri, May 12-14},

pages = {23},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {St. Louis, Missouri},

abstract = {The domestic automakers are currently going through a revolutionary change, not just an evolutionary change, whereas the corporations are changing in their outlook on vehicle size, performance, fuel economy, and organization. General Motors has already spent over $1 billion on the 'X' body vehicles and is planning to spend billions more in the development of smaller, more fuel-efficient vehicles. Ford has spent $700 million to develop a new, smaller pickup truck for 1980, and has a front wheel drive passenger car slated for the market in 1981. Chrysler Corporation has the 'K' car developed and ready for the market. This is dependent on whether or not they can survive long enough to recover from their current economy problems. American Motors, already streamlined and downsized, along with their partnership with Renault, has a very bright future in the auto industry. However, they too have to survive through the next few months or until this recession abates. Volkswagen, the newest entry of domestic automakers, also has a very bright future in the U.S. with one plant assembling cars and trucks to capacity and a second plant scheduled to open in the very near future. The next few months will also be critical to them with respect to economic conditions. 

The primary reason for the domestic automakers' revolutionary changes is due to the need for vast amounts of fuel-efficient vehicles in a very short period of time. It appears that the American public has changed their thinking on vehicle size faster than the auto industry can supply their needs. With the price of fuel continually going up, the domestic buyer has set aside his fondness for the large car and opted for the more fuel-efficient, smaller vehicle. He has, however, not given up his desire to own a personalized vehicle that is loaded with convenience options. For this reason, and because the Federal Government has mandated corporate average fuel economy standards, the automobile industry must downsize their vehicles to meet the demand of today's market. GM, just recently, has laid-off 18,000 white collar workers or 10% of their white collar work force, just to keep money available for their future programs, which they say will not be sacrificed because of the present economic conditions, if at all possible. The NHTSA, in regulating motor vehicles, has affected virtually every portion of the automobile. The following pages reveal some of the standards that affect vehicle weight and what portions of the vehicles were affected by these standards. It shows, although weight was affected, this weight increase was necessary to bring vehicles within the compliance of the law. Since the enactment of the Corporate Average Fuel Economy law (CAFE), which is also the responsibility of the NHTSA, regulating of motor vehicles will be scrutinized much closer than in the past for weight impact. This dual responsibility would lead you to believe that the NHTSA inner departments will be working closer together during their rulemaking activities. Also, because of the fuel economy requirements, and the new regulations that are coming, internal departments within the domestic automakers will naturally be working closer together. If closer, informal communications and cooperation could now be established between the NHTSA and the industry, it would be reasonable to expect future new models to be safer while at the same time more fuel efficient.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1392,

title = {1392. A Method of Analyzing Actual Automotive Weights},

author = {J Webster},

url = {https://www.sawe.org/product/paper-1392},

year  = {1980},

date = {1980-05-01},

booktitle = {39th Annual Conference, St. Louis, Missouri, May 12-14},

pages = {18},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {St. Louis, Missouri},

abstract = {In the last decade estimated car weight as well as actual car weight have taken on new importance in the automotive industry. This is due to both market pressures which have arisen with the advent of the fuel price rise and to increases in the number and stringency of government regulations. Buick has recognized as a result of these and other factors, the need for an organized weighing program at start of production each year. This requires a weight analysis system that delivers: 

1. Timely analysis and 

2. Concise functional data representation. 

The type of weight analysis system needed to reach this goal is dictated by the volume of data necessary to verify the weight estimates. Buick markets over 300 model-engine combinations and in each case calculated estimated weight for both the total car and also the front, rear, and four wheels. This volume of data requires a computer management and analysis system. Figure 1 is an overview of the system. Three separate computer systems with human data handling and decision making between them are necessary.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1322,

title = {1322. Automotive Mass Control From Concept Through Production},

author = {R L Harris},

url = {https://www.sawe.org/product/paper-1322},

year  = {1979},

date = {1979-05-01},

booktitle = {38th Annual Conference, New York, New York, May 7-9},

pages = {12},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {New York, New York},

abstract = {The purpose of this paper is to provide a basic, but broad overview of weight' control in the automotive industry. Since there is no formal means of information exchange within the auto industry, the views presented in this paper reflect observations and involvement within General Motors, and specifically within Buick. It is hoped that this paper can contribute to establishing a common forum with weight engineers in other industries. The exchange of weight control methods should benefit us all.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1323,

title = {1323. A Semiempirical Method for Predicting Urban Railcar Structural Weight},

author = {D M Hooker},

url = {https://www.sawe.org/product/paper-1323},

year  = {1979},

date = {1979-05-01},

booktitle = {38th Annual Conference, New York, New York, May 7-9},

pages = {7},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {New York, New York},

abstract = {In most cases, comparative railcar studies consider weight in terms of weight per unit of length or weight per passenger seat. 

Although dimensionally railcars vary most in length, which does make weight per unit of length an important factor for structure, length alone gives no consideration to the design loads, the materials used, or other dimensional variations. Length can at best offer only an approximation. Weight per passenger seat is even more restricted in this application, since seating configurations can be different in otherwise identical cars. 

This paper provides a semi-empirical trend method for predicting structural weight from dimensions, design loads, and material factors in order to derive a more accurate value. To increase the usefulness of the trend method, only parameters that will be reasonably well known in the early design stage of a railcar have been chosen. 

It is the opinion of the author that if railcar weights were more readily available in a standardized format, better methods of predicting weight would become possible for other subsystems.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1247,

title = {1247. Designing an Electromagnetic Levitation System for High Speed Ground Transportation Vehicles},

author = {P M W Nave},

url = {https://www.sawe.org/product/paper-1247},

year  = {1978},

date = {1978-05-01},

booktitle = {37th Annual Conference, Munich, West Germany, May 8-10},

pages = {7},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Munich, West Germany},

abstract = {The overriding design goals for electromagnetic levitation and guidance systems for high speed vehicles are: minimum weight of the magnets and their power supplies; minimum cross section of the steel armature rails on the track. 

The properties of a magnetic circuit such as force, power, eddy currents etc. and their effects on a magnetic levitation system are surveyed. It is shown how they contribute to the weight of the system. To minimize that a computer algorithm was devised which, for a preselected magnet shape, determines the dimensioning parameters of the maglev system by an iterative procedure. Some of the relationships between the physical parameters involved are mathematically exact, some are approximations based on experience and experiments. Six magnets of different sizes have been calculated and built. Their performance agreed well with the predictions.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1255,

title = {1255. Road Stress Resistance and Lightweight Construction of Automobile Road Wheels},

author = {A Dr. Wimmer},

url = {https://www.sawe.org/product/paper-1255},

year  = {1978},

date = {1978-05-01},

booktitle = {37th Annual Conference, Munich, West Germany, May 8-10},

pages = {20},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Munich, West Germany},

abstract = {At present the world automotive industry is undergoing a unique process of change. The need to save energy and protect the environment requires a reduction in fuel consumption. In the USA legislation has gone as far as requiring the average fuel consumption of all the vehicles sold by a company t o be reduced to 11.8 liters per 100 km by 1980 and to 8.5 liters per 100 km by 1985. These targets can best be achieved by building light. 

As a rough approximation, a weight saving of 100 kg ill reduce fuel consumption by about 1.1 liters per 100 km on urban roads and about 0.5 liters per 140 km on the highway. 

Audi vehicles already have a reputation for light weight construction but we have set out to achieve further considerable weight savings without reducing the dimensions of the vehicle and without affecting durability and passive safety. 

The planned weight savings must be realized within a fixed cost allocation, whereby the additional costs incurred by weight saving measures must be set off by the average saving that the customer will make as a result of lower fuel costs. 

Taking the example of road wheel design, the following analysis is intended to show how minimum weight can be achieved without exceeding certain cost targets.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1256,

title = {1256. Compatibility in Car-To-Car Frontal Collisions},

author = {R Wagner},

url = {https://www.sawe.org/product/paper-1256},

year  = {1978},

date = {1978-05-01},

booktitle = {37th Annual Conference, Munich, West Germany, May 8-10},

pages = {11},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Munich, West Germany},

abstract = {This paper will show a simple test procedure in which any desired car-to-car frontal collision can be replaced by a car-to-barrier collision. The test parameters can be defined on the basis of readily available car specifications, i.e. the car mass and the deformation of the frontal structure in a 30 mph fixed-barrier crash. 

The test procedure is confirmed by the results of a real car-to-car crash and a car-to-barrier crash. A market analysis will supply the frequency distribution of the car masses and the dynamic crush of their frontal structures in the field. If the thus provided data are applied to the test procedure, a crash test procedure permitting the introduction of passive safety features specifically adapted to the automotive conditions in a given market will be obtained.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1257,

title = {1257. Todays Challenge in Rail Transit},

author = {D M Hooker and J M Cord},

url = {https://www.sawe.org/product/paper-1257},

year  = {1978},

date = {1978-05-01},

booktitle = {37th Annual Conference, Munich, West Germany, May 8-10},

pages = {9},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Munich, West Germany},

abstract = {In today's environment of inflation, rising fuel costs, and emerging governmental energy policies, the ability of rail transit for new or proposed city systems to provide the most efficient and economical passenger service is being questioned. 

To meet this challenge, the factors that significantly contribute to the costs of procurement, energy, operation, and maintenance must be identified and addressed. 

This paper compares modal energy relationships and system costs that relate to the current state of the art in rail vehicle design, and suggests possible trends for the future that respond to the needs of cost reduction. 

It concludes that to be successful every aspect of the system requires close attention to the objective. Property specifications, industrial design, and vehicle detail design each has to address procurement, operating, and maintenance costs in order to derive maximum reduction of life-cycle costs.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{1059,

title = {1059. Weight and Performance Characteristics of Magnetically Suspended High-Speed Trains as Compared to Aircraft},

author = {W Herbst},

url = {https://www.sawe.org/product/paper-1059},

year  = {1975},

date = {1975-05-01},

booktitle = {34th Annual Conference, Seattle, Washington, May 5-7},

pages = {22},

publisher = {Society of Allied Weight Engineers, Inc.},

address = {Seattle, Washington},

abstract = {MBB is developing in co-operation with Krauss-Maffei a surface transportation system which is designed to cruise at 

speeds up to 300 mph. The system is using magnetic forces generated by electrical power for lift and cruise propulsion. 

There is an analogy to aircraft which are using aerodynamic forces to maintain motion through air. The paper compares 

the basic performance characteristics of magnetic and aerodynamic forces relevant for the motion of aircraft and 

magnetically suspended high-speed vehicles. As a result weight sensitivities are derived for both types of craft. 

Such weight sensitivities are used as a basis for a comparison of basic economic characteristics.},

keywords = {31. Weight Engineering - Surface Transportation, 32. Product of Inertia Measurement},

pubstate = {published},

tppubtype = {inproceedings}

}