Multiple Loading Conditions Research Articles

Study on validation method for femur finite element model under multiple loading conditions

Acquisition of accurate and reliable constitutive parameters related to bio-tissue materials was beneficial to improve biological fidelity of a Finite Element (FE) model and predict impact damages more effectively. In this paper, a femur FE model was established under multiple loading conditions with diverse impact positions. Then, based on sequential response surface method and genetic algorithms, the material parameters identification was transformed to a multi-response optimization problem. Finally, the simulation results successfully coincided with force-displacement curves obtained by numerous experiments. Thus, computational accuracy and efficiency of the entire inverse calculation process were enhanced. This method was able to effectively reduce the computation time in the inverse process of material parameters. Meanwhile, the material parameters obtained by the proposed method achieved higher accuracy.

Improving Flexibility and Performance of Staged Pressurized Oxy-Combustion

Staged pressurized oxy-combustion (SPOC) is a novel coal combustion power technology being developed by Washington University in St. Louis (WUSTL) that offers the potential to deliver low-carbon power at a reduced cost. Oxy-combustion plants operate by removing most of the nitrogen contained in air prior to combustion, thereby burning fuel in a near-pure oxygen stream instead of air. This combustion produces a flue gas containing primarily carbon dioxide (CO2) and water vapor that allows relatively straightforward CO2 capture. First-generation, atmospheric oxy-combustion technology relies on a flue gas recycle (FGR) diluent to reduce the peak temperatures achieved and the resulting high thermal radiation levels that would otherwise occur in a fuel/oxygen only flame. In contrast, by staging the combustion in several steps, SPOC reduces the peak temperatures of combustion without resorting to a high degree of FGR to control flame temperatures. The SPOC process operates by utilizing two or more pressurized boiler modules connected in series to produce fuel staging; hence, only a portion of the fuel is combusted in any given combustion module. Subsequently the thermal energy released at each stage can be captured and removed from the gases prior to subsequent stages, when more fuel is introduced. This allows the SPOC process to operate with minimal FGR, avoiding the associated efficiency losses and additional costs. While the staging controls the heat release profile in SPOC, operating in a pressurized condition yields a more compact system, reducing modular boiler size and delivering enhanced heat transfer. Additionally, operating at elevated pressures ensures that the latent heat of moisture available from moisture in the fuel and generated by the combustion of the hydrogen content in the fuel can be captured as useful thermal energy for steam turbine integration. This is possible due to elevated dew point from the high partial pressure of the moisture generated in this process, which allows substantial feedwater heater bypassing to be achieved. The inclusion of this thermal energy, normally lost to the atmosphere in traditional combustion processes or to cooling systems in atmospheric oxy-combustion, allows the resultant net efficiency of the SPOC system to be up to 6 percentage points greater than first-generation systems. To begin the process of developing this technology for full-scale application, the Electric Power Research Institute, Inc. teamed up with WUSTL, American Air Liquide, Doosan Babcock, and the U.S. Department of Energy to investigate a practical and workable boiler design concept that would minimize process risks where possible. The SPOC system offers unique process flexibility opportunities due to the staged nature of the combustion, making it a prime candidate for future primary energy delivery where the ability to operate at reduced load in an efficient manner and ramp rapidly will be valuable for balancing intermittent renewable electricity generation. The efficiency of traditional coal-fired power plants is lower at reduced loads below the steam temperature control range due to the challenges in balancing the heat pickup between radiative and convective superheater and reheater surface. Introducing additional heating surface for optimal extended controlled low load operation will likely lead to excessive attemperation at high loads, ultimately leading to a poorer overall cycle efficiency. The SPOC process can facilitate the adjustment of fuel firing rates between stages, targeting heat pickup to where it is most needed and potentially can shut down stages for low-load operation, facilitating an increased steam temperature control range on turndown. The boiler design concept assessment is being carried out to identify the maximum permissible compactness of the SPOC boiler heating surfaces. The assessment will determine the minimum overall height that will deliver appropriate tube operating metal temperatures at full load and achieve rated reheat steam temperatures at low operating loads, balanced against the needs of efficient coal combustion, and the potential resultant slagging and ash environments. The design parameters are being validated by combustion testing in the 100-kWth pressurized combustion test rig at WUSTL. Parameters being investigated include flame stability, fuel burnout, ash composition, radiative heat flux, and temperature profiles. These are being carried out for a range of inlet gas conditions and compositions and at multiple load conditions to investigate combustion stability at reduced load. The results of this testing inform the modeling of the large-scale system, that was sized at 550 MWe to allow direct comparison with the National Energy Technology Laboratory baseline cases for atmospheric oxy-combustion, air firing, and air firing with post-combustion capture.

Auxetics and Other Systems of Anomalous Characteristics

Auxetics and Other Systems of Anomalous Characteristics

Modeling Techniques of Puller Podded Propulsor in Extreme Conditions

This article presents the outcome of a numerical simulation-based research to evaluate the propulsive characteristics of a puller podded propulsor in extreme azimuthing and at multiple initial loading conditions. A Reynolds-Averaged Navier-Stokes (RANS)-based computational fluid dynamics (CFD) code is used to model and predict the propulsive characteristics of the podded propulsor at extreme oblique flow conditions in which highly unsteady, fully 3D, and separated flows exist. The forces and moments of the podded propulsor in the three coordinate directions as well as the thrust and torque of the propeller in static azimuthing conditions in the range of -180°–180° at advance coefficients of 0.20 and 0.8 are predicted and compared with a corresponding dataset obtained in a previous model testing campaign. The predictions of the performance characteristics of the pod unit were within 1–5% of the corresponding measurements, which also captured the nonlinear trends for all the loading conditions, and azimuthing angles. In addition, the velocity and pressure distributions around the podded propulsor as derived from the RANS predictions reveal the highly separated and 3D flow and complex interaction between the propeller and pod-strut bodies, which was more evident in the extreme azimuthing and moderate to light propeller loading conditions. This study demonstrates that the RANS-based CFD code, with proper meshing arrangement, boundary conditions, and setup techniques, can predict the performance characteristics of the podded propulsor in extreme azimuthing and in various loaded conditions with the same level of accuracy of the measurements. 1. Introduction Podded propulsors have the potential to become a popular main propulsion system because they allow more flexibility in the design of the internal arrangement of a ship, potentially reduce noise and vibration, and increase maneuverability (Pakaste et al. 1999; Carlton 2002). The propeller, pod, and strut are the three main components of a podded propulsor. There are multiple propeller-pod-strut configurations that are available commercially, namely the puller type, pusher type, duel-end type, ducted type, and contrarotating type configurations. One of the popular configurations of the podded systems is the puller type, in which the propeller is located upstream of the pod and strut (Islam 2009).

Damage detection methodology under variable load conditions based on strain field pattern recognition using FBGs, nonlinear principal component analysis, and clustering techniques

Structural health monitoring consists of using sensors integrated within structures together with algorithms to perform load monitoring, damage detection, damage location, damage size and severity, and prognosis. One possibility is to use strain sensors to infer structural integrity by comparing patterns in the strain field between the pristine and damaged conditions. In previous works, the authors have demonstrated that it is possible to detect small defects based on strain field pattern recognition by using robust machine learning techniques. They have focused on methodologies based on principal component analysis (PCA) and on the development of several unfolding and standardization techniques, which allow dealing with multiple load conditions. However, before a real implementation of this approach in engineering structures, changes in the strain field due to conditions different from damage occurrence need to be isolated. Since load conditions may vary in most engineering structures and promote significant changes in the strain field, it is necessary to implement novel techniques for uncoupling such changes from those produced by damage occurrence. A damage detection methodology based on optimal baseline selection (OBS) by means of clustering techniques is presented. The methodology includes the use of hierarchical nonlinear PCA as a nonlinear modeling technique in conjunction with Q and nonlinear-T2 damage indices. The methodology is experimentally validated using strain measurements obtained by 32 fiber Bragg grating sensors bonded to an aluminum beam under dynamic bending loads and simultaneously submitted to variations in its pitch angle. The results demonstrated the capability of the methodology for clustering data according to 13 different load conditions (pitch angles), performing the OBS and detecting six different damages induced in a cumulative way. The proposed methodology showed a true positive rate of 100% and a false positive rate of 1.28% for a 99% of confidence.

Pareto Optimal Design of Non‐Homogeneous Isotropic Material Properties for the Multiple Loading Conditions

The present paper concerns two methods: IMD (isotropic material design) and YMD (Young modulus material design) concerning Pareto optimal distributions of the material and its isotropic properties. The merit function is the weighted sum of compliances corresponding to n independent loading conditions. The unit cost of the design is assumed as equal to the trace of the elastic moduli tensor C. In the IMD method, the design variables are the bulk and shear moduli. In the YMD method, the Poisson ratio is assumed as given, possibly non‐uniformly distributed in the design domain, the Young modulus being the only design variable. Both the methods reduce to the auxiliary minimization problem involving statically admissible stress fields corresponding to the subsequent loading conditions. The integrand is expressed by a norm of the collection of these stresses, hence has linear growth. The numerical method proposed refers to the primal formulation: it is based on piece‐wise polynomial approximation of the set of statically admissible stresses. The exemplary Pareto optimal solutions show that admitting negative values of Poisson's ratio may contribute to a decrease of the total compliances.

Study of crack propagation in concrete under multiple loading rates by acoustic emission

It is of great importance to investigate the effect of multiple loading rates on the crack propagation of brittle material such as concrete using acoustic emission because engineering structures are subjected to multiple loading conditions. Although material behaviour under single loading mode has been extensively studied, very limited research has been conducted to investigate the performance of brittle materials subjected to varying loading conditions. This paper presents an experimental study of the effects of single and multiple strain rates on cement mortar samples using acoustic emission. A total number of 81 concrete specimens were tested, in this 28 samples were tested in constant strain rate, whereas rest 53 samples were tested in multiple loading rates. Axial strain, lateral strain and acoustic emission counts were recorded continuously until the specimens had failed. The results showed that concrete behaves differently under multiple loading rates. Acoustic emission was in close agreement with the crack propagation and damage of concrete samples.

Rheological characterization of human brain tissue.

While recent experiments have shaped our understanding of the time-independent, hyperelastic response of human brain tissue, its time-dependent behavior at finite strains and under various loading conditions remains insufficiently understood. In this manuscript, we characterize the rheology of human brain tissue through a family of finite viscoelastic Ogdentype models and identify their parameters for multiple loading modes in four different regions of the brain. We show that even the simplest model of this family, with only one viscoelastic mode and five material parameters, naturally captures the essential features of brain tissue: its characteristic nonlinearity, pre-conditioning, hysteresis, and tension-compression asymmetry. For the first time, we simultaneously identify a single parameter set for shear, compression, tension, shear relaxation, and compression relaxation loading. This parameter set is significant for computational simulations under physiological conditions, where loading is naturally of mixed mode nature. Understanding the rheology of the human brain will help us predict neurosurgical procedures, inform brain injury criteria, and improve the design of protective devices.

Effective coupled thermo-electro-mechanical properties of piezoelectric structural fiber composites: A micromechanical approach

A fully micromechanical model is developed for estimating the effective coupled thermo-electro-elastic material coefficients of three-phase piezoelectric structural fiber composites. The implicit formulations are derived based on the thermo-electro-elastic constitutive laws using a novel extended iso-field micromechanical model under multiple loading conditions. Through numerical examples, the effects of different parameters like fiber volume fractions, ratio of the thickness of piezoelectric shell to the radius of fiber as well as matrix properties on the effective material constants of piezoelectric structural fiber composites are investigated. The present micromechanical formulations have been validated through comparisons with other results available in the open literature.

Topology-optimization-based design method of flexures for mounting the primary mirror of a large-aperture space telescope.

For the development of a large-aperture space telescope, one of the key techniques is the method for designing the flexures for mounting the primary mirror, as the flexures are the key components. In this paper, a topology-optimization-based method for designing flexures is presented. The structural performances of the mirror system under multiple load conditions, including static gravity and thermal loads, as well as the dynamic vibration, are considered. The mirror surface shape error caused by gravity and the thermal effect is treated as the objective function, and the first-order natural frequency of the mirror structural system is taken as the constraint. The pattern repetition constraint is added, which can ensure symmetrical material distribution. The topology optimization model for flexure design is established. The substructuring method is also used to condense the degrees of freedom (DOF) of all the nodes of the mirror system, except for the nodes that are linked to the mounting flexures, to reduce the computation effort during the optimization iteration process. A potential optimized configuration is achieved by solving the optimization model and post-processing. A detailed shape optimization is subsequently conducted to optimize its dimension parameters. Our optimization method deduces new mounting structures that significantly enhance the optical performance of the mirror system compared to the traditional methods, which only focus on the parameters of existing structures. Design results demonstrate the effectiveness of the proposed optimization method.

Discrete topology optimization of ply orientation for a carbon fiber reinforced plastic (CFRP) laminate vehicle door

This study addresses the design of ply orientation for a CFRP vehicle door by implementing a Discrete Material Optimization (DMO) method in a general-purpose commercial finite element code (ABAQUS) and mathematical analysis tool (MATLAB). To accommodate multiple loading conditions, the weighted mean compliance of the CFRP vehicle door was taken as the objective function, subject to the constraints on the local displacements, primary natural frequency and manufacturability. The sensitivities of objective and constraints were calculated by using the strain vectors, which is a more general method than using element stiffness matrices and allows extracting local displacements from the commercial finite element code. A gradient-based algorithm was employed in the DMO approach to tackle the large-scale problem. In the discrete topology optimization, four material penalization schemes were attempted in this study. The proposed DMO approach was compared with the empirical design and the existing method in commercial software. The results demonstrated that the proposed method is able to produce a more competent solution than the empirical design and other optimization methods efficiently.

Role of the Middle Lumbar Fascia on Spinal Mechanics: A Human Biomechanical Assessment.

Biomechanical experiment. The aims of the present study were to test the effect of fascial tension on lumbar segmental axial rotation and lateral flexion and the effect of the angle of fascial attachment. Tension in the middle layer of lumbar fascia has been demonstrated to affect mechanical properties of lumbar segmental flexion and extension in the neutral zone. The effect of tension on segmental axial rotation and lateral flexion has, however, not been investigated. Seven unembalmed lumbar spines were divided into segments and mounted for testing. A 6 degree-of-freedom robotic testing facility was used to displace the segments in each anatomical plane (flexion-extension, lateral bending, and axial rotation) with force and moment data recorded by a load cell positioned beneath the test specimen. Tests were performed with and without a 20 N fascia load and the subsequent forces and moments were compared. In addition, forces and moments were compared when the specimens were held in a set position and the fascia loading angle was varied. A fascial tension of 20 N had no measurable effect on the forces or moments measured when the specimens were displaced in any plane of motion (P > 0.05). When 20 N of fascial load were applied to motion segments in a set position small segmental forces and moments were measured. Changing the angle of the fascial load did not significantly alter these measurements. Application of a 20 N fascial load did not produce a measureable effect on the mechanics of a motion segment, even though it did produce small measurable forces and moments on the segments when in a fixed position. Results from the present study are inconsistent with previous studies, suggesting that further investigation using multiple testing protocols and different loading conditions is required to determine the effects of fascial loading on spinal segment behavior. N/A.

Performance analysis of heat pipe aided NEPCM heat sink for transient electronic cooling

An experimental investigation on the thermal performance of Nano Embedded Phase Change Material (NEPCM) heat sink with heat pipe has been conducted for electronic cooling in Personal computers. The NEPCM and heat pipe configuration in the heat sink effectively eliminates the use of electronic fan. A flat plate heater was used to simulate the computer's microprocessor. The heat sink configurations were placed above the flat plate heater and tested for multiple head load conditions. The addition of NEPCM increases the heat storage capacity, causes a delay effect on the sensible temperature rise and maintained the core temperature of the heat sink at room temperature for prolonged time. Heat pipe charged with R134a refrigerant placed inside the heat sink cavity for regeneration of NEPCM in heat sink. The results showed that use of heat pipe aided NEPCM heat sink caused a 3°C decrease in the heater's surface plate temperature during six hours of the operating period without the help of electronic fan or any other forced convection.

Is an Anterolateral Ligament Reconstruction Required in ACL-Reconstructed Knees With Associated Injury to the Anterolateral Structures? A Robotic Analysis of Rotational Knee Stability

Background: The effect of an anterolateral ligament (ALL) reconstruction on rotational knee stability and corresponding anterior cruciate ligament (ACL) graft forces using multiple knee loading conditions including the pivot-shift phenomenon has not been determined. Purpose: First, to determine the rotational stability and ACL graft forces provided by an anatomic bone–patellar tendon–bone ACL reconstruction in the ACL-deficient knee alone and with an associated ALL/iliotibial band (ITB) injury. Second, to determine the added rotational stabilizing effect and reduction in ACL graft forces provided by an ALL reconstruction. Study Design: Controlled laboratory study. Methods: A 6 degrees of freedom robotic simulator was used to test 7 fresh-frozen cadaveric specimens during 5 testing conditions: intact, ACL-sectioned, ACL-reconstructed, ALL/ITB-sectioned, and ALL-reconstructed. Lateral and medial tibiofemoral compartment translations and internal tibial rotations were measured under Lachman test conditions, 5-N·m internal rotation, and 2 pivot-shift simulations. Statistical equivalence within 2 mm and 2° was defined as P < .05. Results: Single-graft ACL reconstruction restored central tibial translation under Lachman testing and internal rotation under 5-N·m internal rotation torque (P < .05). A modest increase in internal rotation under 5-N·m internal rotation torque occurred after ALL/ITB sectioning of 5.1° (95% CI, 3.6° to 6.7°) and 6.7° (95% CI, 4.3° to 9.1°) at 60° and 90° of flexion, respectively (P = .99). Lateral compartment translation increases in the pivot-shift tests were <2 mm. ALL reconstruction restored internal rotation within 0.5° (95% CI, –1.9° to 2.9°) and 0.7° (95% CI, –2.0° to 3.4°) of the ACL-reconstructed state at 60° and 90° of flexion, respectively (P < .05). The ALL procedure reduced ACL graft forces, at most, 75 N in the pivot-shift tests and 81 N in the internal rotation tests. Conclusion: Although the ALL reconstruction corrected the small abnormal changes in the internal rotation limit at high flexion angles, the procedure had no effect in limiting tibiofemoral compartment translations in the pivot-shift test and produced only modest decreases in ACL graft forces. Accordingly, the recommendation to perform an ALL reconstruction to correct pivot-shift abnormalities is questioned. Clinical Relevance: The small changes in rotational stability after ALL/ITB sectioning would not seem to warrant the routine addition of an ALL reconstruction in primary ACL injuries. Clinical exceptions may exist, as in grossly unstable grade 3 pivot-shift knees and revision knees. However, the concern exists of overconstraining normal tibial rotations.

Modified meta-heuristics using random mutation for truss topology optimization with static and dynamic constraints

AbstractIn this paper, simultaneous size and topology optimization of planar and space trusses subjected to static and dynamic constraints are investigated. All the benchmark trusses consider discrete cross-sectional areas to consider the practical aspect of manufacturing. Moreover, Trusses are considered with multiple loading conditions and subjected to constraints for natural frequencies, element stresses, nodal displacements, Euler buckling criteria, and kinematic stability conditions. Truss topology optimization (TTO) can be accomplished by the removal of superfluous elements and nodes from the highly hyper static truss also known as the ground structure and results in the saving of the mass of the truss. In this method, the difficulties arise due to the singular solution and unnecessary analysis; therefore, FEA model is reformed to resolve these difficulties.The static and dynamic responses to the TTO problems are challenging due to its search space, which is implicit, non-convex, non-linear, and often leading to divergence. Modified meta-heuristics are effective optimization methods to handle such problems in actual fact. In this paper, modified versions of Teaching–Learning-Based Optimization (TLBO), Heat Transfer Search (HTS), Water Wave Optimization (WWO), and Passing Vehicle Search (PVS) are proposed by integrating the random mutation-based search technique with them. This paper compares the performance of four modified and four basic meta-heuristics to solve discrete TTO problems.Highlights Modifications in four different recently developed meta-heuristics. Use of random mutation based strategy. Implementation on challenging/benchmark truss topology optimization problems. Modifications effective over basic algorithms.

Mechanical characterization of human brain tissue.

There is a pressing need to characterize the mechanical behavior of human brain tissue under multiple loading conditions, and to identify constitutive models that are able to capture the tissue response under these conditions. We perform a sequence of experimental tests on the same brain specimen to characterize the regional and directional behavior, and we supplement our tests with DTI and histology to explore to which extent the macrostructural response is a result of the underlying microstructure. Results demonstrate that human brain tissue is nonlinear and viscoelastic, with a pronounced compression-tension asymmetry, and we show that the multiaxial data can best be captured by a modified version of the one-term Ogden model.

Optimal layout of long-gauge sensors for deformation distribution identification

Structural deflection can be identified from measured strains from long gague sensors, but the sensor layout scheme greatly influences on the accuracy of identified resutls. To determine the optimal sensor layout scheme for accurate deflection identification of the tied arch bridge, the method of optimal layout of long-gauge fiber optic sensors is studied, in which the characteristic curve is first developed by using the bending macro-strain curve under multiple target load conditions, then optimal sensor layout scheme with different number of sensors are determined. A tied arch bridge is studied as an example to verify the effectiveness and robustness of the proposed method for static and dynamic deflection identification.

Determination of the in situ mechanical behavior of ankle ligaments

The mechanical behavior of ankle ligaments at the structural level can be characterized by force–displacement curves in the physiologic phase up to the initiation of failure. However, these properties are difficult to characterize in vitro due to the experimental difficulties in replicating the complex geometry and non-uniformity of the loading state in situ. This study used a finite element parametric modeling approach to determine the in situ mechanical behavior of ankle ligaments at neutral foot position for a mid-sized adult foot from experimental derived bony kinematics. Nine major ankle ligaments were represented as a group of fibers, with the force–elongation behavior of each fiber element characterized by a zero-force region and a region of constant stiffness. The zero-force region, representing the initial tension or slackness of the whole ligament and the progressive fiber uncrimping, was identified against a series of quasi-static experiments of single foot motion using simultaneous optimization. A range of 0.33–3.84mm of the zero-force region was obtained, accounting for a relative length of 6.7±3.9%. The posterior ligaments generally exhibit high-stiffness in the loading region. Following this, the ankle model implemented with in situ ligament behavior was evaluated in response to multiple loading conditions and proved capable of predicting the bony kinematics accurately in comparison to the cadaveric response. Overall, the parametric ligament modeling demonstrated the feasibility of linking the gross structural behavior and the underlying bone and ligament mechanics that generate them. Determination of the in situ mechanical properties of ankle ligaments provides a better understanding of the nonlinear nature of the ankle joint. Applications of this knowledge include functional ankle joint mechanics and injury biomechanics.

LiteITD a MATLAB Graphical User Interface (GUI) program for topology design of continuum structures

Over the past few decades, topology optimization has emerged as a powerful and useful tool for the design of structures, also exploiting the ever growing computational speed and power. The design process has also been affected by computers which changed the concept of form into the concept of formation and the emergence of digital design. Topology optimization can modify existing designs, incorporate explicit features into a design and generate completely new designs. This paper will show how topology optimization can be used as a digital tool. The liteITD (lite version of Isolines Topology Design) software package will be described with the purpose of providing a tool for topology design. The liteITD program solves the topology optimization of two-dimensional continuum structures using von Mises stress isolines under single or multiple loading conditions, with different material properties in tension and compression, and multiple materials. The liteITD program is fully implemented in the MATrix LABoratory (MATLAB) software environment of MathWorks under Windows operating system. GUIDE (Graphical User Interface Development Environment) was used to create a friendly Graphical User Interface (GUI). The usage of this application is directed to students mainly (educational purposes), although also to designers and engineers with experience. The liteITD program can be downloaded and used for free from the website: http://www.upct.es/goe/software/liteITD.php.

Biomechanical consequences of adding plantar fascia release to metatarsal osteotomies: Changes in forefoot plantar pressures.

Destruction of the normal metatarsal arch by a long metatarsal is often a cause for metatarsalgia. When surgery is warranted, distal oblique, or proximal dorsiflexion osteotomies of the long metatarsal bones are commonly used. The plantar fascia has anatomical connection to all metatarsal heads. There is controversial scientific evidence on the effect of plantar fascia release on forefoot biomechanics. In this cadaveric biomechanical study, we hypothesized that plantar fascia release would augment the plantar metatarsal pressure decreasing effects of two common second metatarsal osteotomy techniques. Six matched pairs of foot and ankle specimens were mounted on a pressure mat loading platform. Two randomly assigned surgery groups, which had received either distal oblique, or proximal dorsiflexion osteotomy of the second metatarsal, were evaluated before and after plantar fasciectomy. Specimens were loaded up to a ground reaction force of 400 N at varying Achilles tendon forces. Average pressures, peak pressures, and contact areas were analyzed. Supporting our hypothesis, average pressures under the second metatarsal during 600 N Achilles load were decreased by plantar fascia release following proximal osteotomy (p < 0.05). However contrary to our hypothesis, peak pressures under the second metatarsal were significantly increased by plantar fascia release following modified distal osteotomy, under multiple Achilles loading conditions (p < 0.05). Plantar fasciotomy should not be added to distal metatarsal osteotomy in the treatment of metatarsalgia. If proximal dorsiflexion osteotomy would be preferred, plantar fasciotomy should be approached cautiously not to disturb the forefoot biomechanics. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:800-804, 2017.