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1. Finite Element Modeling of Fixed-Fixed Beams Under Shock Excitation With Active Control

   https://doi.org/10.1115/IMECE2025-166672  

   Roberts, Trotter; Gol_Zardian, Mohsen; Satme, Joud N; Downey, Austin_R J (November 2025, American Society of Mechanical Engineers)

   Abstract Effective vibration suppression is vital to ensure the structural integrity of dynamically loaded systems in aerospace, automotive, and manufacturing systems. High-rate dynamic disturbances, such as shocks, impacts, and rapid load changes, produce short-duration, large-magnitude responses that overwhelm conventional damping approaches. Transient dynamics are characterized by non-stationary behavior, model uncertainty, and random variability of external forces, requiring control systems to respond quickly with flexibility. While passive damping systems are very effective in steady-state regimes, they lack responsiveness to handle impulsive disturbances. Active vibration control, on the other hand, offers real-time adjustability in the form of feedback mechanisms to alter structural response on sub-millisecond timescales. In this paper, a model built using the finite element method (FEM) of an impulse-loaded fixed-fixed beam is developed to approximate experimental conditions representative of shock-excited printed circuit boards subjected to drop tower impact. The beam is modeled using a modified Euler-Bernoulli beam theory, where axial degrees of freedom are incorporated alongside conventional transverse and rotational DOFs at each node. This extension enables the simulation of axial loading effects arising from actuator forces, which are axially applied in real-world implementations to induce bending moments. Surface-mounted control actuators are introduced as in-plane force inputs that generate localized moment effects, thereby emulating the behavior of piezoelectric bending actuators. While no direct axial forces are applied as part of the control strategy, the model captures the resulting axial stress distributions and associated geometric stiffening effects implicitly through its structural formulation, while Rayleigh damping and Newmark-Beta time integration schemes are used to simulate transient dynamics. A mesh convergence test confirms model validity under steady-state conditions, and time-domain simulations demonstrate vibration reduction through moment-based actuation. The focus of the work is the enhancement of FEM formulation to accurately describe beam response under dynamic loading and the creation of a computational foundation for evaluating active control techniques. Simulations demonstrate notable reductions in peak displacement and settling time when control forces are activated. This study lays the groundwork for robust, simulation-driven vibration control in high-rate dynamic environments. 

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2. Biomechanical Analysis of Posterior Ligaments of Cervical Spine and Laminoplasty

   https://doi.org/10.3390/app11167645  

   Nishida, Norihiro; Mumtaz, Muzammil; Tripathi, Sudharshan; Kelkar, Amey; Sakai, Takashi; Goel, Vijay K (August 2021, Applied Sciences)

   Cervical laminoplasty is a valuable procedure for myelopathy but it is associated with complications such as increased kyphosis. The effect of ligament damage during cervical laminoplasty on biomechanics is not well understood. We developed the C2–C7 cervical spine finite element model and simulated C3–C6 double-door laminoplasty. Three models were created (a) intact, (b) laminoplasty-pre (model assuming that the ligamentum flavum (LF) between C3–C6 was preserved during surgery), and (c) laminoplasty-res (model assuming that the LF between C3–C6 was resected during surgery). The models were subjected to physiological loading, and the range of motion (ROM), intervertebral nucleus stress, and facet contact forces were analyzed under flexion/extension, lateral bending, and axial rotation. The maximum change in ROM was observed under flexion motion. Under flexion, ROM in the laminoplasty-pre model increased by 100.2%, 111.8%, and 98.6% compared to the intact model at C3–C4, C4–C5, and C5–C6, respectively. The ROM in laminoplasty-res further increased by 105.2%, 116.8%, and 101.8% compared to the intact model at C3–C4, C4–C5, and C5–C6, respectively. The maximum stress in the annulus/nucleus was observed under left bending at the C4–C5 segment where an increase of 139.5% and 229.6% compared to the intact model was observed for laminoplasty-pre and laminoplasty-res model, respectively. The highest facet contact forces were observed at C4–C5 under axial rotation, where an increase of 500.7% and 500.7% was observed compared to the intact model for laminoplasty-pre and laminoplasty-res, respectively. The posterior ligaments of the cervical spine play a vital role in restoring/stabilizing the cervical spine. When laminoplasty is performed, the surgeon needs to be careful not to injure the posterior soft tissue, including ligaments such as LF. 

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3. Intervertebral Disc Mechanics With Nucleotomy: Differences Between Simple and Dual Loading

   https://doi.org/10.1115/1.4050538  

   Yang, Bo; Klineberg, Eric; O'Connell, Grace D. (August 2021, Journal of Biomechanical Engineering)

   null (Ed.)

   Abstract Painful herniated discs are treated surgically by removing extruded nucleus pulposus (NP) material (nucleotomy). NP removal through enzymatic digestion is also commonly performed to initiate degenerative changes to study potential biological repair strategies. Experimental and computational studies have shown a decrease in disc stiffness with nucleotomy under single loading modalities, such as compression-only or bending-only loading. However, studies that apply more physiologically relevant loading conditions, such as compression in combination with bending or torsion, have shown contradicting results. We used a previously validated bone–disc–bone finite element model (Control) to create a Nucleotomy model to evaluate the effect of dual loading conditions (compression with torsion or bending) on intradiscal deformations. While disc joint stiffness decreased with nucleotomy under single loading conditions, as commonly reported in the literature, dual loading resulted in an increase in bending stiffness. More specifically, dual loading resulted in a 40% increase in bending stiffness under flexion and extension and a 25% increase in stiffness under lateral bending. The increase in bending stiffness was due to an increase and shift in compressive stress, where peak stresses migrated from the NP–annulus interface to the outer annulus. In contrast, the decrease in torsional stiffness was due to greater fiber reorientation during compression. In general, large radial strains were observed with nucleotomy, suggesting an increased risk for delamination or degenerative remodeling. In conclusion, the effect of nucleotomy on disc mechanics depends on the type and complexity of applied loads. 

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4. Three-Dimensional Modeling and Finite Element Analysis of the Human Diaphragm

   Shinde, Shantanu (July 2025, University of Houston)

   The diaphragm is a crucial muscle in respiration, creating the pressure gradients necessary for inhalation. This thesis focuses on a computational methodology to reconstruct the diaphragm’s geometry using CT imaging and simulate its biomechanical behavior under physiological loading via Finite Element Analysis (FEA). ITK-SNAP was used for medical image segmentation, CATIA V5 for 3D reconstruction, and ANSYS for simulation under various pressure scenarios. The reconstructed diaphragm model was validated against anatomical landmarks and literature-based deformation ranges, showing good agreement. The proposed workflow provides a robust approach for modeling soft tissue biomechanics. 

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5. Measurement of dynamic deformation during shock loading using a fiber-optic loop-sensor

   https://doi.org/10.1088/1361-6501/ad8ee6  

   Baohui, Yang; Luong, Dung Dinh; Gupta, Nikhil (November 2024, Measurement Science and Technology)

   Abstract Characterizing materials under shock loading has been of interest in fields such as protective material development, biomechanics to study the injury mechanics and high-speed aerodynamic structures. However, shock loading of material is a very short duration phenomenon and it is extremely challenging to develop sensors for dynamic measurements under such loading conditions. Optical fiber sensors present the possibilities to allow high resolution measurement of displacement in such high strain rate loading conditions. This work studies the possibility of using a fiber-optic loop sensor (FOLS) based on the principle of power losses from the curved section for dynamic measurements under shock loading conditions. The displacement results obtained from the optical sensors are compared with the traditional strain gauge and digital image correlation (DIC) measurements. The result obtained by the FOLS closely matched the sensitivity and precision of the strain gauges and had higher precision than that of DIC. 

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