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The Energy Finite Element Analysis (EFEA) has been developed for computing the structural vibration and the interior noise level of complex structural-acoustic systems by solving numerically governing differential equations with energy densities as primary variables. In this paper a complete simulation process for evaluating airborne noise in an automotive vehicle is presented and validated through extensive comparison to test data. The theoretical elements associated with the important paths of the noise transfer from the exterior of the vehicle to the interior acoustic space are discussed. The steps required for developing an EFEA model for a vehicle are presented. The model is developed based on the physical construction of the vehicle system and no test measurements are utilized for adjusting the numerical model.

The Energy Finite Element Analysis(EFEA) is a recent development for high frequency vibro-acoustic analysis, and constitutes an evolution in the area of high frequency computations. The EFEA is a wave based approach, while the SEA is a modal based approach. In this paper the similarities in the theoretical development of the two methods are outlined. The main scope of this paper is to establish the validity of the EFEA by analyzing several complex structural-acoustic systems. The EFEA solutions are compared successfully to SEA results and to solutions obtained from extremely dense conventional FEA models.

This paper presents a validation case study for an Energy Finite Element Analysis (EFEA) formulation through comparison to test data. The EFEA comprises a simulation tool for computing the structural response of a complex structure and the amount of the radiated power. The EFEA formulation presented in this paper can account for periodic stiffeners, for partial fluid loading effects on the outer part of the structure, and for internal compartments filled with heavy fluid. In order to validate these modeling capabilities of the EFEA two 1/8th scale structures representing an advanced double hull design and a conventional hull design of a surface ship are analyzed. Results for the structural vibration induced on the outer bottom part of the structure are compared to available test data. The excitation is applied at two different locations of the deck structure. Good correlation is observed between the numerical results and the test data.

A research scheme and preliminary results of a pilot study concerning upper body coordination in reach movements is presented. Techniques for multi-joint arm movements were used to obtain the kinematics of each body segment in reach movements to targets spatially distributed in a horizontal plane. Further understanding of the control mechanisms associated with coordination is investigated by combining the information of gaze orientation and body segment movements during reach activities. The implicit sequence of body segments in reach movement can be derived from their kinematic characteristics. Moreover, an identification of phases composing a reach movement is attempted.

In this paper the development of statistical metamodels and statistical fast running models is presented first. They are utilized for propagating uncertainties in a multi-discipline design optimization process. Two main types of uncertainty can be considered in this manner: uncertainty due to variability in design variables or in random parameters; uncertainty due to the utilization of metamodels instead of the actual simulation models during the optimization process. The value of the new developments and their engagement in multi-discipline design optimization is demonstrated through a case study. An underwater vehicle is designed under four different disciplines, namely, noise radiation, self-noise due to TBL excitation, dynamic response due to propulsion impact loads, and response to an underwater detonation.

Simulation of reach movements is an essential component for proactive ergonomic analysis in digital human modeling and for numerous applications in vehicle design. Most studies on reach kinematics described human movements in static conditions. Earlier studies of reach performance in vibration environments focused mainly on fingertip deviation without considering multi-body dynamics. However, for the proper assessment of reach performance under whole-body vibration exposure, a multi-body biodynamic model needs to be developed. This study analyzes three dimensional reach kinematics of the upper extremity during in-vehicle operations, using a multi-segmental model of the upper body in the vibratory environment. The goals are to identify the characteristics of upper body reach movements and to investigate vibration-induced changes in joint kinematics. Thirteen subjects reached to four target directions in the right hemisphere.

Solidification paths and phase stability have been investigated in the creep resistant Mg-Al-Ca based alloys for powertrain applications. The liquidus projection and isothermal sections of the Mg-Al-Ca ternary system were determined, including a ternary (Mg, Al)2Ca intermetallic compound. The solidification of the alloys in the α-Mg primary phase field involves L→α+(Mg, Al)2Ca eutectic reaction in a wide range of compositions and is terminated with invariant reactions that form Mg2Ca or Mg17Al12 phases. The (Mg, Al)2Ca is a high temperature phase and decomposes into Mg2Ca and Al2Ca phases between 773 and 673 K, but the transformation is kinetically quite slow at temperatures below 473 K. Based on this new knowledge, alloy modifications through quaternary elemental additions to improve the solid-solution strength and aging treatments to reinforce the α-Mg phase with precipitates have been demonstrated.

Exhaust Gas Recirculation (EGR) coolers are commonly used in diesel and modern gasoline engines to reduce the re-circulated gas temperature. A common problem with the EGR cooler is a reduction of the effectiveness due to the fouling layer primarily caused by thermophoresis, diffusion, and hydrocarbon condensation. Typically, effectiveness decreases rapidly at first, and asymptotically stabilizes over time. There are several hypotheses of this stabilizing phenomenon; one of the possible theories is a deposit removal mechanism. Verifying such a mechanism and finding out the correlation between the removal and stabilization tendency would be a key factor to understand and overcome the problem. Some authors have proposed that the removal is a possible influential factor, while other authors suggest that removal is not a significant factor under realistic conditions.

Compositional and microstructural variations in a casting can often result in rather significant variations in the response to a given aging treatment, leading to location dependent mechanical properties. The objective of this study is to determine the effect of copper content and solidification rate on the aging behavior of a type 319 cast aluminum alloy. The nominal composition of the alloy is Al-7% Si-3.5% Cu-0.25% Mg, however, typical secondary 319 aluminum specifications allow copper levels to vary from 3-4%. Solidification rates throughout a casting can vary greatly due to, among other factors, differences in section size. To determine the effect of copper level and solidification rate on the aging response, aging curves were experimentally developed for this alloy. Three different copper levels (3, 3.5, 4%) and two solidification rates were used for this study. Aging temperatures ranged from 150-290°C with nine aging times at each temperature.

The hybrid FEA method combines the conventional FEA method with the energy FEA (EFEA) for computing the structural vibration in vehicle structures when the excitation is applied on the load bearing stiff structural members. Conventional FEA models are employed for modeling the behavior of the stiff members in the vehicle. In order to account for the effect of the flexible members in the FEA analysis, appropriate damping and spring/mass elements are introduced at the connections between stiff and flexible members. Computing properly the values of these damping and spring/mass elements is important for the overall accuracy of the computations. Utilizing in these computations the analytical solutions for the driving point impedance of infinite or semi-infinite members introduces significant approximations.

The Energy Finite Element Analysis (EFEA) has been validated in the past through comparison with test data for computing the structural vibration and the radiated noise for Naval systems in the mid to high frequency range. A main benefit of the method is that it enables fast computations for full scale models. This capability is exploited by using the EFEA for a submarine pressure hull design optimization study. A generic but representative pressure hull is considered. Design variables associated with the dimensions of the king frames, the thickness of the pressure hull in the vicinity of the excitation (the latter is considered to be applied on the king frames of the machinery room), the dimensions of the frames, and the damping applied on the hull are adjusted during the optimization process in order to minimize the radiated noise in the frequency range from 1,000Hz to 16,000Hz.

In the Energy Finite element Analysis (EFEA) method, the governing differential equations are formulated for an energy variable that has been spatially averaged over a wavelength and time averaged over a period. A finite element approach is used for solving the differential equations numerically. Therefore, a library of elements is necessary for modeling the various wave bearing domains that are present in a structural-acoustic system. Discontinuities between wave bearing domains always exist due to the geometry, from a change in material properties, from multiple components being connected together, or from different media interfacing with each other. Therefore, a library of joints is also necessary for modeling the various types of physical connections which can be encountered in a structural-acoustic system.

In this paper, the results of finite element analyses for nodular cast irons with different volume fractions of graphite particles based on an axisymmetric unit cell model under uniaxial compression and tension are presented. The experimental compressive stress-strain data for a nodular cast iron with the volume fraction of graphite particles of 4.5% are available for use as the baseline material data. The elastic-plastic stress-strain relation for the matrix of the cast iron is estimated based on the experimental compressive stress-strain curve of the cast iron with the rule of mixture. The elastic-plastic stress-strain relation for graphite particles is obtained from the literature. The compressive stress-strain curve for the cast iron based on the axisymmetric unit cell model with the use of the von Mises yield function was then obtained computationally and compared well with the compressive stress-strain relation obtained from the experiment.

Analytical stress intensity factor solutions for welds in lap-shear specimens of equal thickness under pinned and clamped loading conditions based on the beam bending theory are presented and examined. Finite element analyses are also employed to obtain the stress intensity factor solutions for welds in lap-shear specimens under both clamped and pinned loading conditions. The computational solutions are compared well with the analytical solutions. The results of the analytical and computational solutions indicate that the bending moments at the clamped edges reduce the mode I and II stress intensity factor solutions by about 7% to 10% for the given specimen geometry. The effects of the clamped grips depend on the ratio of the weld width to the specimen length. Comparisons of the stress intensity factor solutions suggest that the fatigue lives of the welds in lap-shear specimens under clamped loading conditions should be higher than those under pinned loading conditions.

In this paper, mode I and mode II stress intensity factor solutions for gas metal arc welds in single lap-shear specimens are investigated by the analytical stress intensity factor solutions and by finite element analyses. Finite element analyses were carried out in order to obtain the computational stress intensity factor solutions for both realistic and idealized weld geometries. The computational results indicate that the stress intensity factor solutions for the realistic welds are lower than the analytical solutions for the idealized weld geometry. The computational results can be used for the estimation of fatigue lives in a fatigue crack growth model under mixed mode loading conditions for gas metal arc welds.

In this paper, the analytical stress intensity factor and J integral solutions for welds in lap-shear specimens of two dissimilar sheets based on the beam bending theory are first reviewed. The solutions are then presented in the normalized forms. Next, two-dimensional finite element analyses were selectively conducted to validate the analytical solutions based on the beam bending theory. The interface crack parameters, the stress intensity factor solutions, and the J integral solutions for welds in lap-shear specimens of different combinations of steel, aluminum, and magnesium, and the combination of aluminum and copper sheets of different thickness ratios are then presented for convenient fracture and fatigue analyses. The transition thickness ratios for critical crack locations for different combinations of dissimilar materials are then determined from the analytical solutions.

Automotive seats are commonly described by one-dimensional measurements, including those documented in SAE J2732. However, 1-D measurements provide minimal information on seat shape. The goal of this work was to develop a statistical framework to analyze and model the surface shapes of seats by using techniques similar to those that have been used for modeling human body shapes. The 3-D contour of twelve driver seats of a pickup truck and sedans were scanned and aligned, and 408 landmarks were identified using a semi-automatic process. A template mesh of 18,306 vertices was morphed to match the scan at the landmark positions, and the remaining nodes were automatically adjusted to match the scanned surface. A principal component (PC) analysis was performed on the resulting homologous meshes. Each seat was uniquely represented by a set of PC scores; 10 PC scores explained 95% of the total variance. This new shape description has many applications.

Sandwich panels with high modulus/high strength skin material and low density/low modulus core material have higher stiffness-to-weight ratio than monolithic panels. In this paper, sandwich panels with corrugated core are explored as a lightweighting concept for improved stiffness. The skin and the core materials are a high strength steel, aluminum alloy or carbon fiber-epoxy composite. The core has a triangular corrugation, a trapezoidal corrugation and a rectangular corrugation. The stiffness of the sandwich panels is analytically determined and compared with monolithic panels of equal mass. It is shown that the stiffness of the sandwich panels is 5 to 7 times higher than that of the monolithic panels.

In this paper, residual stress distributions in rectangular bars due to rolling or burnishing at very high rolling or burnishing loads are investigated by roll burnishing experiments and three-dimensional finite element analyses using ABAQUS. First, roll burnishing experiments on rectangular bars at two roller burnishing loads are presented. The results indicate the higher burnishing load induces lower residual stresses and the higher burnishing load does not improve fatigue lives. Next, in the corresponding finite element analyses, the roller is modeled as rigid and the roller rolls on the flat surface of the bar with a low coefficient of friction. The bar material is modeled as an elastic-plastic strain hardening material with a nonlinear kinematic hardening rule for loading and unloading.

Simulations conducted on-board in a vehicle control module can offer valuable information to control strategies. Continued improvements to on-board computing hardware make online simulations of complex dynamic systems such as drivetrains within reach. This capability enables predictions of the system response to various control actions and disturbances. Implementation of online simulations requires model initialization that is consistent with the physical drivetrain state. However, sensor signals and estimated variables are susceptible to errors, compromising the accuracy of the initialization and any future state predictions as the simulation proceeds through the numerical integration process. This paper describes a drivetrain modeling and analysis method that accounts for initialization errors, thereby enabling accurate simulations of system behaviors.