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This article investigates the feasibility of utilizing adaptive kinematics to reduce the computational effort of finite element modeling of progressive damage and global failure in fiber-reinforced composite laminates. In the present context, adaptive kinematics refers to the selective use of different types of macroscopic laminate models for different regions of the computational domain, based on the solution complexity within each region. Each of these macroscopic laminate models can be distinguished by the manner in which the displacement field is assumed to vary through the thickness of the laminate. In the present study, kinematic adaptivity is made possible through the use of variable kinematic finite elements (VKFE) that are developed by hierarchically combining two or more types of assumed displacement fields in a single finite element domain. The hierarchical data structure of the VKFE greatly simplifies the process of connecting elements that represent different types of laminate theories, thus facilitating adaptive analysis. The adaptive kinematic concept is demonstrated for the bending of simply supported laminates that exhibit diffuse, widespread damage and laminate tensile test specimens that exhibit very intense localized damage due to the free edge effect. The results obtained in this study clearly demonstrate that the use of adaptive kinematics can significantly reduce the overall computational effort of progressive damage solutions without compromising solution accuracy.

This article examines the distribution of strain energy in the various component materials of actuated plates and investigates the manner in which the strain energy distribution is influenced by the actuated span-to-thickness ratio and the thickness of the adhesive bond layer. Furthermore, the article investigates the effect of modeling choices (e.g., kinematic assumptions and mesh density) on the predicted magnitude and mode of the dominant strain energy form in each component material. These computed parameters can be used to quantify the overall efficiency of an actuated plate in addition to aiding the understanding of the local mechanics that govern the process. The focus problem consists of a square aluminum plate with a single symmetric pair of surface-mounted piezoceramic actuators that are used to produce in-plane extension or bending in the aluminum plate. The behavior of the actuated plate is examined over a range of plate thicknesses and adhesive bond layer thicknesses by using a series of finite element models that feature different levels of kinematic complexity and different levels of two-dimensional (2-D) mesh density. The results of the study emphasize the need for discrete layer kinematics in determining the magnitude and mode of the dominant strain energy form in each constituent material; however, these computed parameters are shown to be rather insensitive to changes in 2-D mesh density. Most importantly, the study confirms the existence and quantifies the magnitude of the local kinematic effect, whereby a portion of the available actuation energy is diverted to the production of localized transverse shear deformation and transverse normal deformation, thus reducing the amount of actuation energy available to produce in-plane deformation in the structural substrate.

This article discusses finite element modeling of progressive damage in the adhesive bond layers of actuated plates and investigates the reduction in actuation capacity caused by the damaged bond layers. The primary challenge posed by this class of problems stems from the vast range of geometric scales that are represented, with the thickness of the adhesive layer representing the smallest scale, the overall thickness of the actuated plate representing the intermediate scale, and the in-plane dimensions of the plate representing the largest scale. In multiscale problems, the overall efficiency of the numerical methodology is of paramount importance, thus model development is guided by the need to obtain a sufficiently accurate solution at an acceptable computational expense. In this study, this goal is achieved through the use of a hierarchical, displacement-based, 2-D finite element model that includes the first-order shear deformation (FSD) model, Type I layerwise models (LW1) and Type II layerwise models (LW2) as special cases. Both the LW1 layerwise model and the more familiar FSD model use a reduced constitutive matrix that is based on the assumption of zero transverse normal stress; however, the LW1 model includes discrete layer transverse shear effects via in-plane displacement components that are C0 continuous with respect to the thickness coordinate. The LW2 layerwise model utilizes a full 3-D constitutive matrix and includes both discrete layer transverse shear effects and discrete layer transverse normal effects by expanding all three displacement components as C0 continuous functions of the thickness coordinate. The hierarchical finite element model incorporates a 3-D continuum damage mechanics model that predicts local orthotropic damage evolution and local stiffness reduction at the geometric scale represented by the individual material ply or, in the case of layerwise models, by the individual numerical layer. The results clearly demonstrate that the resulting model can efficiently simulate progressive damage in the adhesive layers. For rectangular actuator patches, the adhesive damage is highest near the corners of the actuator and is driven primarily by local concentrations in the transverse normal and transverse shear stresses. In contrast to previous studies that have shown that the inclusion of discrete layer transverse normal stress does not significantly influence the predicted global deformations, the present study shows that the transverse normal stress has a very significant effect in the initiation and progression of localized damage in the adhesive layers.

An s-adaptive finite element procedure is developed for the transient analysis of 2-D solid mechanics problems with material non-linearity due to progressive damage. The resulting adaptive method simultaneously estimates and controls both the spatial error and temporal error within user-specified tolerances. The spatial error is quantified by the Zienkiewicz-Zhu error estimator and computed via superconvergent patch recovery, while the estimation of temporal error is based on the assumption of a linearly varying third-order time derivatives of the displacement field in conjunction with direct numerical time integration. The distinguishing characteristic of the s-adaptive procedure is the use of finite element mesh superposition (s-refinement) to provide spatial adaptivity. Mesh superposition proves to be particularly advantageous in computationally demanding non-linear transient problems since it is faster, simpler and more efficient than traditional h-refinement schemes. Numerical examples are provided to demonstrate the performance characteristics of the s-adaptive method for quasi-static and transient problems with material non-linearity.

For the simple case of a homogeneous, isotropic plate with a single, symmetric pair of actuators, previous work by the authors has demonstrated the importance of including discrete layer kinematics in predicting the global response of the actuated plate. The inclusion of discrete layer kinematics permits accurate modeling of the so-called local kinematic effect, whereby a portion of the total actuation is diverted to the production of localized transverse shear deformation near the edges of the actuator, thus reducing the amount of actuation energy available to produce the desired global deformation mode. The present study expands upon this previous effort, investigating the magnitude of the local kinematic effect for more complex actuated plates involving fiber-reinforced laminated composite substrates with multiple symmetric pairs of actuators. The results obtained from finite element simulations using a wide range of kinematic assumptions conclusively demonstrate that as the actuated span-to-thickness ratio decreases, the models with discrete layer kinematics predict a smaller global response than the models that use equivalent-single-layer kinematics. Thus, the local kinematic effect is observed to influence the global response of the actuated plates regardless of the material constitution of the structural substrate and regardless of the in-plane spacing between actuator pairs.

The linear systems of equations generated by the Superconvergent Patch Recovery technique (Int. J. Numer. Methods Eng. 1992; 33:1331–1382; Comput. Methods Appl. Mech. Eng. 1992; 101:207–224) can exhibit rank deficiency under certain purely geometric conditions. The rank deficiency problem can be corrected simply and efficiently by utilizing a local rotated co-ordinate system. This rotated SPR procedure is easily automated and adds robustness to automatic adaptive solution methods. Copyright © 2006 John Wiley & Sons, Ltd.

The effects of accurately accounting for transverse shear strain, transverse normal strain, and discrete layer kinematics on the computed global response of actuated plates are investigated using a hierarchical displacement-based, two-dimensional (2-D) finite element model that is developed specifically for composite laminates. The hierarchical model is used to obtain the first-order shear deformation model, a higher-order cubic equivalent-singlelayer model, a type-I layerwise model, and a type-II layerwise model as special cases. Each of the first three models uses a reduced constitutive matrix that is based on the assumption of zero transverse normal stress; however, the models differ significantly in their assumed distribution of transverse shear strain. The type-II layerwise model utilizes a full 3-D constitutive matrix and includes both discrete layer transverse shear effects and discrete layer transverse normal effects. The scope of the study is restricted to homogeneous plates with surface-mounted actuators covering a wide range of span-to-thickness ratios. The results clearly demonstrate that as the span-to-thickness ratio of the actuated region decreases, discrete layer kinematics become very important for accurately characterizing the global response of the actuated plate. The set of laminate kinematic assumptions utilized by a particular model influence the predicted global response primarily through the so-called local kinematic effect where a portion of the available actuation energy is diverted to the production of localized transverse shear deformation and localized transverse normal deformation in the vicinity of the actuator edges, thereby reducing the amount of actuation energy that is available for producing the intended global deformation mode.

In this article an efficient 3-D continuum damage mechanics formulation for composite laminates and its implementation into a finite element model that is based on the first order shear deformation theory of laminates are described. In the damage formulation each composite ply is treated as a homogeneous orthotropic material that can exhibit orthotropic damage in the form of distributed microscopic cracks that are normal to the three principal material directions. This type of damage is efficiently described by a symmetric second order tensor field that serves as an evolving internal variable within the framework of irreversible thermodynamics. The damage tensor is continuous within each material ply of a given element, but can be discontinuous across material layer boundaries and inter-element boundaries. The resulting finite element formulation is shown to be robust, stable and efficient for the simulation of progressive damage and global failures in large-scale composite laminate problems. Numerical ex...

This paper investigates the effects of discrete layer transverse shear strain and discrete layer transverse normal strain on the predicted progressive damage response and global failure of fiber-reinforced composite laminates. These effects are isolated using a hierarchical, displacement-based 2-D finite element model that includes the first-order shear deformation model (FSD), type-I layerwise models (LW1) and type-II layerwise models (LW2) as special cases. Both the LW1 layerwise model and the more familiar FSD model use a reduced constitutive matrix that is based on the assumption of zero transverse normal stress; however, the LW1 model includes discrete layer transverse shear effects via in-plane displacement components that are C 0 continuous with respect to the thickness coordinate. The LW2 layerwise model utilizes a full 3-D constitutive matrix and includes both discrete layer transverse shear effects and discrete layer transverse normal effects by expanding all three displacement components as C 0 continuous functions of the thickness coordinate. The hierarchical finite element model incorporates a 3-D continuum damage mechanics (CDM) model that predicts local orthotropic damage evolution and local stiffness reduction at the geometric scale represented by the homogenized composite material ply. In modeling laminates that exhibit either widespread or localized transverse shear deformation, the results obtained in this study clearly show that the inclusion of discrete layer kinematics significantly increases the rate of local damage accumulation and significantly reduces the predicted global failure load compared to solutions obtained from first-order shear deformable models. The source of this effect can be traced to the improved resolution of local interlaminar shear stress concentrations, which results in faster local damage evolution and earlier cascading of localized failures into widespread global failure.

An adaptive finite element procedure is developed for modelling transient phenomena in elastic solids, including both wave propagation and structural dynamics. Although both temporal and spatial adaptivity are addressed, the novel feature of the formulation is the use of mesh superposition to produce spatial refinement (referred to as s-adaptivity) in transient problems. Spatial error estimation is based on superconvergent patch recovery of higher-order accurate stresses and is used to guide mesh adaptivity, while the temporal error estimation is based on the assumption of linearly varying third-order time derivatives of the displacement field and is used to adjust the time step size for the HHT-α variant of the Newmark direct numerical integration method. Spatial adaptivity of the mesh is performed using a hierarchical h-refinement scheme that is efficiently implemented using a structured version of finite element mesh superposition. This particular spatial adaptivity scheme is extremely fast and consequently makes it feasible to repeatedly update both the mesh and the time increment as required in an adaptive transient analysis. This work represents the initial effort in applying this type of spatial adaptivity to transient problems. Three example problems are given to demonstrate the performance characteristics of the s-adaptive procedure. Copyright © 2005 John Wiley & Sons, Ltd.

A displacement-based variable kinematic global–local finite element model is developed using hierarchical, multiple assumed displacement fields at two different levels: (1) at the element level, and (2) at the mesh level. The displacement field hierarchy contains both a conventional plate expansion (2-D) and a full layerwise (3-D) expansion. Depending on the accuracy desired, the variable kinematic element can use various terms from the composite displacement field, thus creating a hierarchy of different elements having a wide range of kinematic complexity and representing a number of different mathematical models. The VKFE is then combined with the mesh superposition technique to further increase the computational efficiency and robustness of the computational algorithm. These models are used to analyse a number of laminated composite plate problems that contain localized subregions where significant 3-D stress fields exist (e.g. free-edge effects).

A variable kinematic finite element (VKFE) model based on an hierarchical, multiple assumed displacement field is combined with the mesh superposition technique to determine local stress fields in surface-bonded piezoelectric actuated plates. The displacement field hierarchy contains both a conventional 2D plate expansion and the full layerwise expansion of Reddy. The combination of VKFE and the mesh superposition technique further increases the computational efficiency and robustness of the computational algorithm to determine local stress fields and global response accurately.

A review of equivalent–single–layer and layerwise laminated plate theories and their finite element models is presented. The layerwise theory advanced by the senior author is presented and a variable displacement finite element model and mesh superposition techniques are described. A simultaneous multiple model approach that is based on the variable kinematic theory and the mesh superposition method are also described. The objective of the simultaneous multiple model approach is to match the most appropriate mathematical model with each subregion based on the physical characteristics, applied loading, expected behavior, and level of solution accuracy desired in that subregion. Thus solution economy is maximized without sacrificing the solution accuracy.

The layerwise laminate theory of Reddy (1987) is used to develop a layerwise, two-dimensional, displacement-based, finite element model of laminated composite plates that assumes a piecewise continuous distribution of the tranverse strains through the laminate thickness. The resulting layerwise finite element model is capable of computing interlaminar stresses and other localized effects with the same level of accuracy as a conventional 3D finite element model. Although the total number of degrees of freedom are comparable in both models, the layerwise model maintains a 2D-type data structure that provides several advantages over a conventional 3D finite element model, e.g. simplified input data, ease of mesh alteration, and faster element stiffness matrix formulation. Two sample problems are provided to illustrate the accuracy of the present model in computing interlaminar stresses for laminates in bending and extension.

The static and dynamic interaction between a bonded piezoelectric actuator and an underlying beam substructure is investigated using four different displacement-based finite element models all of which are derivable from the generalized laminate plate theory of Reddy. Two 'equivalent single-layer' models and two multi-layer models are developed and compared in order to ascertain the level of model complexity necessary to accurately represent piezoelectric actuation of beam structures.

This chapter provides an overview of issues that are important in finite element modeling of progressive damage and failure in fiber-reinforced composite laminates. Topics discussed include the multiscale nature of composite laminate problems, equivalent single layer and layerwise laminate theories and models, macroscopic failure theories, computational homogenization and localization, and the application of continuum damage mechanics to composite laminate problems, with emphasis on methods that are practical for large scale analysis of composite structural components. Keywords: finite elements; composite laminates; damage; failure

Anti-Tac(Fv)-PE38 (LMB-2) is a recombinant, single-chain immunotoxin composed of the variable domains of the anti-Tac (anti-CD25) monoclonal antibody fused to a truncated form of Pseudomonas exotoxin (PE). Until now, this agent has been reported to be very cytotoxic toward T-cell but not B-cell leukemic cells freshly obtained from patients and is being tested clinically in patients with CD25+ malignancies of both B- and T-cell origin. Hairy cell leukemia (HCL) is a B-cell malignancy in which the cells are usually CD25+ and their ex vivo sensitivity to LMB-2 was unknown. Malignant cells from the first HCL patient to be tested were very sensitive to the cytotoxic effect of LMB-2 in vitro (IC50, 1.1 ng/ml), and this patient responded clinically to LMB-2 administered systemically. Therefore, we decided to assess the potential clinical utility of LMB-2 in other patients with HCL. We tested fresh leukemic cells from nine additional CD25+ HCL patients. LMB-2 was very cytotoxic ex vivo in all patients with IC50s as low as 0.5 ng/ml. Malignant cells freshly obtained from patients with chronic lymphocytic leukemia were also sensitive to LMB-2 but not as sensitive as cells from HCL patients. These results indicate that CD25+ HCL is a B-cell neoplasm that is particularly sensitive to LMB-2, and this agent may be useful in patients who have failed standard therapies.

Two global/local finite element modeling procedures are integrated to permit the analysis of localized three-dimensional affects in laminated composite plates with bonded or embedded actuators. The first technique concerns the use of variable kinematic finite elements which are elements that contain several different types of assumed displacement fields. By choosing appropriate terms from the composite displacement field, an entire array of elements with different levels of kinematic complexity can be formed. The different elements can be conveniently connected together in a single domain for global/local analysis. The second technique concerns the use of finite element mesh superposition in which an independent overlay mesh is superimposed on a global mesh to provide localized refinement for regions of interest regardless of the original global mesh topology. Integration of these two ideas yields a very robust, economical analysis tool for global/local analysis of composite laminates.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A finite element modeling methodology is developed for the hierarchical, global/local analysis of laminated composite plates. The method incorporates a new variable kinematics, displacement-based, finite element that is developed using a multiple assumed displacement field approach. The variable kinematic elements provide a great degree of flexibility in defining the transverse (through thickness) variation of the assumed displacement field. The resulting finite element model permits different subregions of the computational domain to be described by different mathematical models. Enforcing displacement continuity along subregion boundaries requires only the specification of certain homogeneous essential boundary conditions, thus avoiding the inconvenience of multi-point constraints, penalty function methods, or special transition elements.

The layer—wise laminate theory of Reddy [1] is used to study interlaminar stress fields and carry out progressive failure analysis of composite laminates. The layer-wise theory not only predicts accurate interlaminar stress fields but it also provides a convenient format for modeling multiple delaminations. The computational model based on the layer—wise theory is capable of modeling free edge effects and energy release rates with the same accuracy as a conventional 3-D finite element model. The progressive failure analysis is based on an algorithm in which the damage is accounted through phenomenalogical failure criteria and a stiffness reduction coefficient. The stiffness reduction coefficient is used to define the equivalent material properties, which are used to update the stiffness matrix. It is demonstrated through an example problem that three-dimensional stress analysis is a necessary requirement but not sufficient to predict the failure behavior of composites laminate accurately.

Body measurement requirements of human engineering specialists cannot be fully met by the use of traditional anthropometry. The human engineer needs anthropometric data which can be used to describe the spatial location, configuration, and mobility of both external and internal landmarks for prescribed operator tasks and workspaces. In order to accomplish this goal, multidisciplinary studies are needed that will incorporate the fields of anthropometry, biomechanics, statistics, ergonomics and others.

The primary experimental methodologies of human impact tolerance research require the availability of anthropometric and other body measurement information. Somewhat standard anthropometric procedures are available to describe human volunteer and general populations exposed to dynamic situations. However, classical anthropometry is inadequate to the task of specifying joint mobility and resistance to force. In addition, no common procedures or lists of useful measurements are available for cadaver or laboratory animal subjects. These factors have led to major shortcomings in the current designs of crash test dummies and the parallel input data sets required for the operation of computerized mathematical crash victim simulations. The paper briefly reviews the problems and the activities being carried out for their resolution.

This paper presents the initial results of a research project concerning the mechanism of head injury. In order to begin to define the mechanism, it is necessary to determine mechanical properties of the various skull bones, organize them into constitutive equations, and develop a structural model of the skull.

This paper presents the concepts and first group of test results from a project designed to: quantify thoracic impact response using cadaver and baboon subjects; compile analytical functions relating thoracic kinematic response to injuries observed in the experiments; and define performance specifications insuring response fidelity between human and surrogate thoraxes. The experiments, which vary G-level, velocity, and direction of impact, utilize restraint systems including belts, airbags, and EA-columns. Resulting injuries are recorded at autopsy and an AIS rating assigned. Using the kinematic accelerometer data, injury-predictive functions are generated using statistical regression procedures. The utilization of project results in developing performance specifications for surrogate thoraxes is discussed in conclusion.

Selected side-impact cases from the National Crash Severity Study (NCSS) were studied to determine similarities and differences between actual crashes and laboratory (sled) crash tests. Of the 91 cases studied, 51 were judged comparable to the laboratory situation. Injuries for the 51 cases were tabulated by crash severity (Delta V) and were judged to be quite similar to those observed in laboratory (sled) tests at a slightly higher Delta V. Brief notes are appended concerning each of the reviewed cases.

This paper presents the various features and operational properties of a two-dimensional mathematical model of crash victim motions. The features of this model include: (1) An eight mass representation of the human body where contact between the crash victim and the vehicle is represented in terms of independent force-deformation properties of the victim and the vehicle. (2) An extensible multijoint neck and a realistically flexible shoulder joint. (3) A real- line representation of the vehicle interior or exterior where shape is given as a network of points. (4) Specific predictive restraint device submodels for the airbag, the energy absorbing steering column, and a slipping, energy absorbing three-point-belt restraint system. (5) A flexible output package including graphics, an injury criteria monitor, and a variety of options for listing, deleting, and comparing selected output variables.

The purpose of this paper is to describe a combination of state-of-the-art detailed accident investigation procedures, computerized vehicle crash and occupant modelling, and biomechanical analysis of human injury causation into a method for obtaining enhanced biomechanical data from car crashes. Four accident cases, out of eighteen investigated, were selected for detailed reconstruction. Three were frontal impacts while the fourth was lateral. The CRASH II and MVMA 2-D analytical models were used in the reconstruction process. Occupant motions, force interactions with vehicle components, accelerations on the various body segments, and much other information was produced in the simulation process and is reported in this paper along with scene and injury data from the accidents. The major conclusion reached was that the reconstructions, using largely preliminary data for the occupant and vehicle, were evaluated and the dynamic loadings predicted for application to the car occupants yielded injury results which were generally within accepted ranges of human tolerance data. Additional conclusions were reached about the quality of data describing the occupant, car, and accident needed for analytical reconstruction. For the covering abstract of the conference see HS-036 716. (Author/TRRL)

A SERIES OF MATHEMATICAL MODELS OF THE INTERACTION BETWEEN AN OCCUPANT AND THE INTERIOR OF A VEHICLE IS PRESENTED. THE FOLLOWING PARAMETER STUDIES USING AN EIGHT-MASS, TWO-DIMENSIONAL MODEL ARE DISCUSSED; BELT MATERIAL PROPERTIES, BELT SLACK, BELT GEOMETRIC CONFIGURATION, AND COMPARISON OF SEATS WITH AND WITHOUT HEADRESTS IN REAR IMPACT. IN ADDITION, IT IS DEMONSTRATED BY EXAMPLE THAT SIMPLE MATHEMATICAL MODELS CAN PERFORM A VALUABLE SERVICE IN LAYING THE GROUNDWORK FOR MORE SOPHISTICATED ANALYTICAL AND EXPERIMENTAL WORK AS WELL AS YIELDING SHORT TERM RESULTS. FINALLY, THREE-DIMENSIONAL MODELS ARE DISCUSSED. IT IS SHOWN THAT A THREE-MASS, THREE-DIMENSIONAL MODEL IS A LOGICAL EXTENSION OF CURRENT SIMULATION EFFORTS IN ORDER TO PROVIDE INSIGHT INTO OCCUPANT RESPONSE IN OBLIQUE AND LATERAL IMPACT AS WELL AS NONSYMMETRIC RESTRAINT SYSTEM. /AUTHOR/

One of the primary difficulties in providing adequate simulation of human response during a crash has been the lack of data describing human response under similar circumstances. Because of the medical care problems which may arise from volunteer tests, the bulk of the testing has been performed under the sponsorship of governmental agencies who can provide a proper medical staffing and hospital care facilities should they become necessary.

During recent years, the Highway Safety Research Institute (HSRI) has developed and validated two- and three-dimensional models describing the motions and forces acting upon an occupant during a collision. These inexpensive-to-operate models are performing with approximately 90% accuracy in parametric studies of classical crash configurations. In our own validation procedures, contacts with automobile development and design groups, and discussions with federal agencies, certain shortcomings of mathematical modeling procedures have been isolated. These include primarily the inability of the user to determine and input data to the computer programs and also to specify force, motion, velocity, and acceleration output data in a form applicable to the various vehicle design, human tolerance, and compliance tasks for which the models have been developed. As a part of the development of a new six-mass, three-dimensional crash victim simulator, a user-oriented interactive input/output language (OVERLORD) has been developed and is operational at HSRI. The objective of this tool is to make use of the HSRI and other similar models accessible to persons not highly trained in computer use. The program itself selects and positions the occupant in the vehicle and then automatically conducts the simulation. This is accomplished in a "conversation" between the user and the computer. The program asks the user certain basic questions such as: 1. What percentile occupant do you desire? 2. What is the impact velocity as well as type and direction of impact? 3. What standard vehicle geometry is desired~standard, compact, subcompact? The new three-dimensional model and the OVERLOAD program that prepares the input data, executes the computer run, and submits the output back to the user are described in detail in the paper. Comparisons between the predictions of the new model, predictions of the older HSRI three-dimensional crash victim simulator, and experimental data are included in the paper.

A parameter study is performed involving several analytical vehicle occupant models in current use, with investigation of neck representations a primary goal. Side, oblique, and rear impact situations are investigated. Attention is given to the effects of varying head-neck mass and moments of inertia, anthropometry, muscle strength, and location, as well as strength of motion-limiting "stops." A model that replaces the conventional simple ball-joint neck with a two-joint, extensible neck is studied. This model also makes use of joint-stop ellipses to approximate the anatomical range for relatively free angular motion at a joint. Allowance is made for the effect of muscle contraction on occupant dynamics as a function of the degree of voluntary or involuntary tightening of the muscles, based upon experimental findings. A discrete parameter neck model that treats the cervical spine as a linkage of rigid vertebrae and massless, deformable discs is discussed briefly. It is determined that, besides being extensible and having at least two joints, three-dimensional neck representations should account for coupling between the forces resisting the three possible rotational motions~for example, yaw, pitch, and roll~that can occur between the head and the torso.

A technique has been developed for measuring the six possible independent motions (three translational and three rotational) of a rigid body. The technique was developed specifically to measure head motions of an anthropometric dummy during simulated oblique and lateral crashes using an impact sled. Under such test conditions, body motions may be highly non-symmetric making a complete three-dimensional analysis necessary.© (1973) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A STUDY HAS BEEN CONDUCTED AS AN INITIAL STEP IN DETERMINING THE DIFFERENCES OBSERVED BETWEEN THE MOTIONS OF A LIVING HUMAN IMPACT SLED TEST SUBJECT AND A DUMMY TEST SUBJECT. THE MECHANISM WHICH IS PROPOSED FOR ACCOMPLISHING THIS IS THE HSRI TWO-DIMENSIONAL MATHEMATICAL CRASH VICTIM SIMULATOR. A SERIES OF MEASUREMENTS WERE TAKEN ON HUMAN TEST SUBJECTS INCLUDING CLASSICAL AND NONCLASSICAL ANTHROPOMETRIC MEASUREMENTS, RANGE OF MOTION MEASUREMENTS FOR THE JOINTS, AND MAXIMUM FOOT FORCE MEASUREMENTS. A SERIES OF MATHEMATICAL EXPRESSIONS HAS BEEN USED TO PREDICT BODY SEGMENT WEIGHT, CENTERS OF GRAVITY, AND MOMENTS OF INERTIA USING THE RESULTS OF THE VARIOUS BODY MEASUREMENTS. IT WAS THEN POSSIBLE TO PREPARE A DATA SET FOR USE WITH THE MATHEMATICAL MODEL. IN ADDITION TO THE BODY MEASUREMENTS DESCRIBED ABOVE, IT WAS NECESSARY TO DETERMINE THE DECELERATION PROFILE FOR THE DAISY SLED AND TO DETERMINE THE GEOMETRY AS WELL AS THE FORCE-DEFORMATION CHARACTERISTICS FOR THE SEAT AND RESTRAINT ENVIRONMENT. THIS BEING ACCOMPLISHED, A COMPUTER SIMULATION OF AN IMPACT SLED TEST INVOLVING A HUMAN VOLUNTEER WAS MADE. /SAE/