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Many types of three dimensional mechanism (3D-mechanism) are used in modern industry. Specially, in automation technology, coordinate measuring machines (CMMs) play the key role. With the improvement of measurement accuracy conventional coordinate measuring machine (CMM) can’t meet the demand of 3D measurements of fine parts, so Nano-CMM (Coordinate Measuring Machine with nanometer resolution) appears in the world. This paper presents a novel structure design of Nano-CMM. The new structure named symmetrical-bridge is developed based on the analysis of conventional Nano-CMM. Compared with Nano-CMMs called rectangular-bridge and arch-bridge, this new structure performs less static deformation and provides higher accuracy under the same load. The analysis and comparison of three Nano-CMMs were made through ANSYS software, so it can be easily concluded that this new structure not only has great static rigidity but also dynamic rigidity.

In view of the fact that quality control is becoming more and more important and that the time for developing new mechanical parts decreases, optical nondestructive testing methods are very useful in industry. Especially, speckle interferometry. This paper describes three different interferometric nondestructive testing systems. A 3D-Holography-System, a Shearography-System and an Interferoscope are presented in order to enable a qualitative and quantitative evaluation. These three systems are used to examine a STAB-O-FOCS (an automatic Flap Opening and Closing System). The exterior of the strained housing is examined by holographic and shearographic means. Usually when measuring internal deformations the chassis has to be opened. With an interferoscope it is possible to examine inner structures through a small hole. Often such holes are available, for example an sensor which is inserted into the chassis of the STAB-O-FOCS.

Digital 3D profilometry is a non-contact, full-field, and fast method for 3D profile digitization. It has a relatively simple setup and acceptable measurement accuracy. Traditional phase shifting technique uses single frequency fringe pattern for coding the depth information and an unwrapping procedure is required for decoding. Usually, the object has to be a continuous surface without any disconnected part or large height discontinuities. In this paper, a new method of three-frequency fringe pattern is presented to measure objects with complicated structures, which have large surface height discontinuities, or contain separated components. Principles and procedures are described. Experimental application is given and limitations are discussed.

Energy dissipation due to micro-slip in joints is the primary source of damping in many vehicle and space structures. This paper presents results on how the surface topology may be modified to increase the energy dissipation in joints. An analytical solution for general forms of contact pressure of a one-dimensional micro-slip problem is presented. The solution indicates how the contact pressure should be distributed to maximize the energy dissipation. Two dimensional contact pressures are optimized using finite element methods in combination with numerical optimization methods and the results are used to modify the surface topology in bolted joints in order to increase the energy dissipation during loading. The predicted increase of energy dissipation is validated with physical testing. A direct result of the study is a washer with varying thickness increasing the energy dissipation in joints and hence the structural damping of joined structures.

Self Piercing Riveting (SPR) is widely used in the assembly of steel frame buildings and aluminium vehicle bodies. This paper investigates the dimensional variation resulting from the SPR process which until now has received little attention. The distortion of sheet metal in the normal and in-plane directions during joining are investigated separately. Firstly, the effects of the main SPR joining parameters: sheet thickness, joining sequence, riveting pitch and sheet rolling direction on the distortion in the normal or out of plane direction are presented for simple lap joints. Secondly, the distortion in the in-plane direction was investigated using simple flat, strip panels. It has been found that the dimensional variation in aluminium SPR joining can be significant and the major factors affecting the level of distortion are identified.

One of the main objectives of the automotive industry is to build more fuel efficient cars. The most dominant factor, among the many that determine fuel efficiency, is the weight of the vehicle. Any overall attempt to reduce weight involves all areas of the vehicle. Over the years the industry has addressed this need by developing new or modified materials and innovative production processes, combining these with one another and transforming them into viable production solutions. A very successful approach among the many things done is the use of structural metal adhesives, which have brought significant improvements in body shell rigidity and crash behavior. Traditionally, aluminum, steel and other metal parts were joined together with mechanical or thermal methods, such as rivets or resistance welding. But, structural adhesive is now an alternative that engineers consider very seriously. With any adhesive joint, the goal is to achieve as uniform a stress distribution as possible.

The highly competitive auto industry is looking for ways to reduce product development cycle time while meeting the corporate and government stringent vehicle performance requirements. Quasi-static or dynamic analytical fatigue life assessment of automotive structures consumes more time because of the use of long proving ground time histories and large finite element models with more than a million elements. A representative static load case that highlights all the durability concern locations is needed for making fast design iterations. This paper describes a simple technique to extract a static load case that correlates to minimum fatigue life at various locations of the body structure and the method of using this load case for fast iterations before validating the final design with fatigue analysis using full proving ground loads. The usefulness of this static load case in solving sheet metal and spot weld fatigue issues is demonstrated with an example.

In this contribution an efficient and modular method is presented to simulate fatigue crack propagation within the framework of linear-elastic fracture mechanics. The FEM code ABAQUS/Standard is used to simulate the load/displacement history of the considered 3D shell structure using 6-node triangular shell or continuum elements while the preprocessor ANSA is applied to employ remeshing. In order to efficiently simulate fatigue crack propagation in large finite element models a sub-model is extracted from the global model. The submodel is subjected to the kinematics given at the interface to the global model. Concerning fracture mechanics theory the stress intensity factor concept is applied. Stress intensity factors are calculated from the finite element mesh within an ABAQUS user subroutine using a novel variant of the well-known displacement correlation technique.

Two thread forming processes, rolling and cutting, were studied for their effects on fatigue in cast aluminum 319-T7. Material was excised from cylinder blocks and tested in rotating-bending fatigue in the form of unnotched and notched specimens. The notched specimens were prepared by either rolling or cutting to replicate threads in production-intent parts. Cut threads exhibited conventional notch behavior for notch sensitive materials. In contrast, plastic deformation induced by rolling created residual compressive stresses in the notch root and significantly improved fatigue strength to the point that most of the rolled specimens broke outside the notch. Fractographic and metallographic investigation showed that cracks at the root of rolled notches were deflected upon initiation. This lengthened their incubation period, which effectively increased fatigue resistance.

Plastic materials are often used for automotive fuel tanks today because of their light weight, freedom for forming complicated shapes and corrosion resistance. Fatigue behavior of the high-density polyethylene applied to fuel tanks was analyzed under low-level cyclic loading that simulated fuel tank pressure changes. The correlation between fatigue life and stress, temperature and frequency (the major influencing factors) was expressed quantitatively using fatigue test data for test pieces. This expression was then verified in fatigue tests conducted on plastic fuel tanks. The validity of this equation for predicting the fatigue life of plastic fuel tanks was thus confirmed.

In this study, the finite element analysis of hydroform tooling system using three different surface-to-surface contact methodologies is evaluated, such as the traditional non-linear gap element methodology, the newer linear gap technology and the 3D non-linear surface contact algorithm. These methods are investigated with the help of case studies, from exercise model level to more complicated models of real parts. Key parameters like analysis results, computational time and ease of use for each method are discussed. Directions regarding adaptivity to local user’s software resources and implementation strategies are provided. The linear gap method is observed to be more effective as pre-processing and computing time with same accuracy results as the non-linear static method in the design stage of hydroform tools analysis with pure sliding.

This paper describes a methodology to characterize external crush patterns for NASS CDS crash cases. Further, external vehicle crush patterns for cases where crash induced fires and fuel leakage occurred were the focus of this study. External crush measurements for frontal, side and rear crash cases collected by NASS/CDS investigators from 1995-2004 were compiled. For frontal, side and rear damage areas, the 10th, 25th, 50th, 75th and 95th percentile crush levels were calculated and plotted. Based on crash deltaV, an evaluation of high, moderate and low severity impacts with varied collision types was performed. Results are plotted. Results of this evaluation provides a graphical representation of the most commonly deformed regions per crash type in order to provide guidance for optimized placement of wiring, fuel lines and gas tanks.

To aid in understanding die wear when stamping AHSS, a study to characterize the contact pressure distribution in drawbeads during stamping had been undertaken. As direct measurement of contact pressure for a drawbead is not feasible during metal flow, a combination of experimental and Finite Element (FE) simulation techniques were used to determine the contact pressure distributions and the maximum contact pressure for a number of different conditions. Testing was conducted using the Drawbead Simulator (DBS) for two different bead configurations. The materials in this investigation were 0.7mm and 0.8mm EG BH210 and EG DP500. Static Implicit FE analyses were conducted with ABAQUS Standard using 2D plane strain continuum elements. A combined hardening model in conjunction with strain rate effects was used to describe material behavior as it flows through the drawbeads.

The influence of surface roughness on the dynamic friction behavior of AA5754-O aluminum was evaluated with single-pull friction experiments in three significantly different surface roughness conditions: polished to a 1.0 μm diamond finish, polished with 8 %, and polished with 16 % uniaxial plastic strain. The surfaces were examined before and after the friction tests with confocal microscopy. The changes observed in the dynamic friction coefficient between the polished and roughened surfaces imply that the influence of surface roughness on the friction may reach a steady state prior to 8 % plastic strain. The friction test also produced distinct changes in: the topographic images; the plots of both the probability density and the 2-point correlation function ensembles determined from the topographic data; and the numeric quantities calculated from the probability density and 2-point correlation data.

Six Sigma methodologies in combination with Lean thinking have made considerable inroads as continuous improvement tools initially in manufacturing and more recently for service and transactional processes. There is considerable interest globally in training professionals on the use and application of these tools appropriate to either operational or transactional areas. It has long been realized that adult learning is at its best when participants are involved in relevant “hands-on” experiments. Six Sigma training has seen the use of class room demonstrations ranging from the use of playing cards, simulations and to the use of sophisticated experiments to illustrate concepts of factorial designs. This paper will focus on a series of simple but modular experiments that were developed over the past two years illustrating the application of all the Statistical tools that are taught as a part of Six Sigma Green and Black Belt body of knowledge.

Using data from the Fatality Analysis Reporting System, the National Automotive Sampling System's Crashworthiness Data System and General Estimates System, and combined state data from Idaho, Illinois, and Maryland, we examined crashes accompanied by fire. Vehicles weighing less than 10,000 lbs were analyzed, and were further categorized by type. Differences in fire rates were found in the examination of many of the factors reviewed. The distribution of fires occurring at various points of impact is different from the distribution of impact in all crashes. Crashes accompanied by fire occur more frequently after frontal collisions and are less likely to occur after side or rear impact collisions. The strongest indicator of fire is the amount of energy in the crash. Therefore, vehicle speed and the type of object or vehicle struck during the crash are relevant factors in collisions accompanied by fire.

Traditionally on-centre steering has been evaluated by a sine wave steering input through-centre. This method is widely used to characterise the on-centre steering characteristics of vehicles. Although it enables a wide range of key parameters to be quantified such as on-centre stiffness and hysteresis, the test does not encompass how the vehicle responds when an input is made from or returning to the straight running condition. The objective of this study was to propose additional on-centre evaluation methods that would include the response of the car from straight ahead running. A range of vehicles were then tested in accordance with these methods using a combined IMU/GPS system. The data from this testing was analysed to determine what measures might be useful in quantifying the response of a vehicle from straight ahead running. Then using the data obtained from this group of vehicles provide reference information on the upper and lower limits of these measures.

The realistic simulation of vehicle-trailer combinations and the development of controllers for vehicle trains require comprehensive models for the dynamics of vehicle and trailer as well as a numerically feasible representation of the hitch. While the equations of motion for the two chassis can be reduced to systems of ordinary differential equations, introducing the coupling yields additional algebraic constraints on the relative vehicle-trailer motion. In this paper, a numerical algorithm for the simulation of vehicle trains is presented which overcomes the stability and drift-off phenomena known from the treatment of differential-algebraic equations and achieves real-time capability. Numerical results from simulations with a commercial vehicle dynamics program are shown proving its effectiveness for different vehicle-trailer combinations and demanding driving maneuvers.

Recent rollover resistance test results show discrepancies between vehicles steered with programmable steering machines and those steered by test drivers. This paper examines the differences in steering profiles and their effects on vehicle dynamics. For decades, test drivers have steered vehicles through rollover resistance test maneuvers. Human inputs, however, can cause variability from test to test. The National Highway Traffic Safety Administration (NHTSA) is currently performing rollover testing with steering machines in an effort to objectively rate the rollover resistance of passenger vehicles. The trapezoidal steer inputs are visibly different from human inputs and may be responsible for test differences. The roll rate feedback loop, which determines steer timing, may also affect vehicle response.

Road simulators reproduce measured service environments in laboratory based test rigs and have contributed significantly to improving the structural integrity and quality of modern vehicles. These rigs are driven by data that are derived from a specified response and the frequency response function of the test rig in an iterative process. This paper introduces an alternative iterative procedure that converges to a valid drive file in fewer iteration steps than the current algorithm.