Splitting Force Research Articles

An Experimental Method to Determine the Interstitial Splitting Forces and Thermal Load Input Induced by Self-Tapping and Self-Drilling Bone Screws: A Pilot Study

Background: The aim is to evaluate methods to quantify the interstitial splitting force and thermal load input of self-tapping and self-drilling osteosynthesis screws. Methods: A specialized modular test bench was developed to measure the induced splitting force of self-drilling and self-tapping osteosynthesis screws using porcine mandibular bone. In addition, a fundamentally new approach to measure the temperature near the contact zone of osteosynthesis screws (fiber-optic sensor in the axis of the screw) was established. Results: The self-drilling screw type induces a splitting force of about 200 N in the surrounding tissue, so that microdamage of the bone and increased resorption can be assumed. Even pre-drilling induces a short-time force into the tissue, which is comparable to the splitting force of the self-tapping screw. The temperature increase in the screw is clearly higher compared to the temperature increase in the surrounding tissue, but no significant difference in temperature between the two screw types could be measured. Based on the measured temperatures of both screw types, the temperature increase in the contact zone is considered critical. Complications during the screwing process caused by the manual tool guidance resulted in numerous breakages of the fiber-optic sensors. Conclusions: The developed methods provide additional insight regarding the thermomechanical load input of self-drilling and self-tapping screws. However, based upon the optical fiber breakages, additional refinement of this technique may still be required.

Fracture stiffness evaluation with waterless cryogenic treatment and its implication in fluid flowability of treated coals

Cryogenic fracturing using liquid nitrogen is a waterless and environmentally friendly formation stimulation method for creating complex fracture networks effectively. This study developed a non-destructive geophysical technique using seismic measurements to probe fluid flow through coal and ascertain the effectiveness of cryogenic fracturing. A theoretical model is established to determine the fracture stiffness of coal inverted from wave velocities, which serves as the nexus for correlating the hydraulic and seismic properties of fractures. In response to thermal shock and frost forces, visible cracks are observed on coal surfaces that deteriorate the mechanical properties of the coal bulk. Consequently, the wave velocity of frozen coal specimens exhibits a general decreasing trend with freezing time under both dry and saturated conditions. For a gas-filled specimen, both the normal and shear fracture stiffness decrease monotonically with freezing time as more cracks are created in the coal bulk. For a water-filled specimen, ice formation due to cryogenic treatment leads to grouting of the coal bulk. Accordingly, the fracture stiffness of wet coal increases initially and then decreases with freezing time. A coalbed with higher water saturation is preferable when applying cryogenic fracturing because fluid-filled cracks can endure larger cryogenic forces before complete failure, and the contained water aggravates coal breaking as ice pressure builds up from the volumetric expansion of the water–ice phase transition and applies additional splitting forces on pre-existing or induced fractures and cleats. Also confirmed is that the stiffness ratio is sensitive to fluid content. The measured stiffness ratio is 0.7–0.9 for dry coal but less than 0.3 for saturated coal. The present findings provide a basis for realistic estimation of coal stiffness ratio for future discrete fracture network modeling.

Exploratory Study on the Fracture Resistance of Cast Glass

The emerging interest in the architectural applications of cast glass components reveals a knowledge gap on the mechanical properties of cast glass. Apart from its chemical composition, cast glass is characterized by its manufacturing history and thermal profile, often inheriting a set of defects that define its properties. The role that inhomogeneities in the bulk of voluminous glass components have on the strength of the final product is also uncertain. Systematic testing is therefore necessary for the safe structural application of cast glass. Towards this direction, the presented research aims to experimentally investigate the fracture resistance of cast glass under sharp contact loading, by means of a customized splitting test using a sharp linear indenter. Cubic specimens with 50 mm sides are kiln-cast at low forming temperatures, employing a variety of silicate-based cullet and firing schedules and their inherent defects are documented. The results of the splitting tests show that the borosilicate specimens fail at the highest splitting force, followed by the soda lime float specimens, while the fused or porous specimens have a significantly lower resistance to fracture. The strength order of the various glasses, as this results from the splitting tests- is opposite to that found earlier in four-point bending tests, due to the different fracture mechanisms activated. The fracture resistance of a glass specimen is governed, first by its ability to deform around the indenter to relief the developing stresses and then by its bond strength to resist crack propagation. Thus, a good balance between glass network flexibility and high bond dissociation energy is required, explaining why the tested homogeneous borosilicate and soda lime glasses are more resistant than the modified soda lime compositions with high alkali content. In addition, the fractographic analysis indicates that the non-stress inducing flaws in the bulk have a negligible contribution to the fracture resistance of the specimens.

Influence of geometrical parameters on the splitting forces in textile-reinforced concrete

Splitting forces due to bond action can lead to the premature failure of reinforced concrete structural components. In earlier research it was mentioned that it is mainly geometrical parameters that play a key role in the distribution and magnitude of the splitting forces in textile-reinforced concrete. However, so far no accurate geometrical characterisation of textile reinforcement has been performed which considers all the relevant properties of the material such as the regularly repeating variation in cross-sectional dimensions. In this paper, four geometrical parameters are introduced which permit a clear geometrical characterisation of fibre strands and allow for the comparison of different types of textile reinforcement. Furthermore, a broad parametric study was carried out for a pull-out test in which the parameters were varied, and the influence of these parameters on the splitting forces occurring in textile-reinforced concrete was visualised. Based on this parametric study, a mechanical model was established, which takes into account experimental data from previous research. This model allows for the calculation of the splitting forces occurring in textile-reinforced concrete when one short fibre strand is pulled out of the concrete.

The Alveolar Ridge Splitting Technique on Maxillae: A Biomechanical Human Cadaveric Investigation.

The alveolar ridge splitting technique (ARST) offers an alternative to classic ridge augmentation techniques for successful insertion of dental implants. However, the buccal lamella is at risk of fracturing during ARST distraction. To better understand the fracture mechanisms and displacement limits of the split lamella, this study conducted biomechanical tests on human cadaveric maxilla specimens having extremely atrophied alveolar ridges treated with ARST. A total of 12 standardized alveolar splits were prepared on the maxillae of 3 elderly female donors using an oscillating piezoelectric saw. Mimicking the surgical distraction process of the lamella, each split was tested to failure using a dental osteotome attached to the crosshead of an electromechanical testing system. All specimens were scanned by means of high-resolution peripheral quantitative computed tomography prior to and post testing to evaluate split geometries and failure modes. Split stiffness, failure force, and displacement were 27.4 ± 18.7 N/mm, 12.0 ± 8.4 N, and 0.97 ± 0.31 mm, with no significant differences between anatomical sides and split locations (p ≥ 0.17). Stiffness correlated significantly with failure force (R2 = 0.71, p < 0.01). None of the alveolar split widths correlated significantly with the outcomes from biomechanical testing (p ≥ 0.10). The results suggest that simple geometrical measures do not predict the allowed extent of lamella distraction prior to failure. More sophisticated methods are required for surgical planning to optimize the ARST outcomes. Still, the present study may advocate a clinical protocol for the maxilla where the implant site is prepared directly after osteotomy setting and immediately before full lamella dislocation, when the lamella is still stable, resistant to mechanical stress, and bone loss caused by the abrasion of the burr is minimized.

Oral Fine Motor Control of Teeth Treated with Endodontic Microsurgery: A Single-Blinded Case-control Study

IntroductionPeriodontal mechanoreceptors (PMRs) are refined neural receptors present in abundance at the root apex and have a pivotal role in oral fine motor control. This case-control study aimed to evaluate the oral fine motor control of teeth treated with endodontic microsurgery (EMS) in comparison with the control teeth using a standardized behavioral biting task. MethodsFourteen eligible participants performed 5 trials of an oral fine motor control task that involved holding and splitting half of a peanut positioned on a force transducer with their EMS treated tooth and its contralateral control incisor tooth (28 teeth in total). The outcome variables were the mean food holding force, intra- and intertrial variability of the holding force, food splitting force, splitting duration, and the frequency of the stepwise splitting phase. The data were analyzed with parametric and nonparametric tests. ResultsThe results showed no statistically significant differences in the holding force, inter- and intratrial variability of the holding force, splitting force, or splitting duration between the teeth treated with EMS and the control (P > .05). However, there was a significantly higher frequency of stepwise ramp increase during the splitting phase with EMS treated teeth compared with the control (48% and 37%, respectively; P < .05). ConclusionsEMS treated teeth showed similar force regulation and oral fine motor control as the contralateral control. The findings of this study suggest that EMS treatment does not perturb the sensory information of PMRs and maintains the force regulation and oral fine motor control of the teeth.

Visualization and quantification of aggregate and fiber in self-compacting concrete using computed tomography for wedge splitting test

Wedge splitting test gained popularity as a stable and simple method to predict the fracture mechanism properties of concrete specimens. The present research focuses on understanding the behavior of self-compacting concrete specimens made with and without steel fibers tested using wedge splitting test, later scanned under high resolution computed tomography. The contribution of hooked end steel fiber and coarse aggregates in fiber reinforced specimens was compared without steel fiber reinforced concrete specimens using high resolution computed tomography. As fracture takes place across the plane perpendicular to the splitting force, i.e. along the depth of specimens. High resolution computed tomography technique was adopted in visualizing the changes taking place across the matrix, coarse aggregate and steel fibers, along with the specimen’s depth. Datasets of the images, obtained from computed tomography, after images analysis and volume reconstruction, revealed a higher coarse aggregate and steel fiber participation in the failure region of without and with fibers specimens. Computed tomography investigation indicated a total of 23 coarse aggregate and 64 steel fibers participated in resisting the failure, during wedge splitting test of without and with fibers specimens. Therefore, high resolution computed tomography can be used in understanding, quantifying the participation of coarse aggregate and steel fiber in the failure plane, under fracture loads.

Ability to adjust occlusal force in implant-supported overdenture wearers.

The purpose of this study was to evaluate the occlusal force adjusting ability of implant-supported overdenture (IOD) wearers, as compared with natural teeth and complete dentures. Subjects were those with natural dentition (ND group; 19 subjects), those with implant-supported overdentures (IOD group; 7 subjects), and those with complete dentures (CD group; 14 subjects). Subjects were asked to hold test foods (peanuts and biscuits mounted on a custom-made apparatus with a force transducer) between their anterior incisors (hold phase) and split test foods (split phase). The mean value of the occlusal force during the hold phase (hold force), the peak force rate during the split phase (peak force rate), the time required to split test foods (duration), and the maximum occlusal force in the split phase (split force) were selected as outcomes. Data were analyzed with Wilcoxon's signed rank test, the Kruskal-Wallis test, and multiple regression analysis (Statistical significance levels: 5%). For peanuts, the peak force rate for the ND group was significantly higher than the IOD and CD groups. The duration of the CD group was significantly longer than the ND and IOD groups. Multiple regression analysis indicated that even with adjustment for age and sex, there were significant differences in the peak force rate between the ND and the IOD, CD groups, and in the duration between the ND and CD group. Subjects with IODs showed superior ability to adjust occlusal force, as compared with complete dentures, although it didn't match the natural dentition.

Crush testing approach for flat-plate fibrous materials

A novel crush testing approach is presented to obtain crush properties of flat-plate fibrous materials. To validate the proposed approach, fully constrained specimens of different materials were crushed. The inevitable component, the splitting force, included in the measured force, emanating from shearing, tearing, and friction at specimen edges, is isolated and deducted, resulting in the crushing force. An approximately linear relationship between the energy associated with the measured force and the specimen width was observed, suggesting width independent splitting energy. Consistent specific energy absorption (SEA) properties of fully supported flat-plate specimens were obtained using the proposed approach.

Loop-Free Tie-Down Node with an Anchor Rod-Dowel for a Hollow-Core Floor Slab of Formwork-Free Shaping

When designing buildings and structures for various purposes, the specialists should find new decisions for the possibility of using structures made using the long-line formwork-free technology, including hollow-core floor slabs, namely: installation without free lengths of reinforcement, lifting without the tie-down loops, joint units with other structure elements, configuration of sections with new geometrical parameters. As the hollow-core slabs of formwork-free shaping are produced without tie-down loops, the problems of installation and transportation of these slabs are discussed. Examples of tie-down nodes installation in the slabs produced by the formwork-free shaping technology were considered in the paper, with the justification of the complexity of their installation in such slabs and the increased metal consumption. The aim is to reduce the laboriousness of rigging work and to provide a gripping device for a hollow-core slab of formwork-free shaping when removing it from a long-line pallet, storing, loading and installing this slab during the construction process. A constructive-technological decision was proposed for a tie-down node installed in the slab body without the use of a tie-down loop and having only an anchor rod-dowel through which the tie-down of a slab could be directly done without the use of traditional tie-down loops. The node was designed with reduced metal consumption and does not change the technology of manufacturing hollow-core slabs of formwork-free shaping. The theoretical basis for calculating the bearing capacity of the proposed tie-down node, installed in a hollow-core slab of formwork-free shaping was determined and summarized. It was revealed that the bearing capacity of the proposed tie-down node installed in the body of a hollow-core slab, under the action of lifting loads, depends on the splitting force of concrete protective layer located above the anchor rod-dowel of this node (all things being equal). The theoretical data of the study were validated by full-scale tests of slabs with tie-down nodes installed in their body, carried out in accordance with the proposed structural-technological development. The operational suitability of the proposed tie-down nodes with an anchor rod-dowel for the hollow-core slabs of formwork-free shaping and the possibility of their implementation at other enterprises of the country having production lines for long-line formwork-free shaping were stated. A tie-down node with an anchor rod-dowel, proposed to be installed in a hollow-core slab of formwork-free shaping, can be used in other reinforced concrete structures produced by the technology of long-line formwork-free shaping. A patent for a utility model has been received for the development of a loop-free tie-down node for a hollow-core slab of formwork-free shaping.

Microenvironment-Controlled Micropatterned Microfluidic Model (MMMM) for Biomimetic In Situ Studies.

Attachment of trophozoites to the intestine is an indispensable step for Giardia's survival and pathogenicity in almost 280 million infections worldwide each year. However, the analysis of the attachment mechanism is difficult due to the lack of methods that can create a favorable microaerobic atmosphere. Herein, we developed an osmotic-pressure, pH, excretion, nutrition, gas, ionic-strength, flow-rate, and temperature microenvironment-controlled micropatterned microfluidic model to simulate the in vivo microenvironment to study in situ the stress applied to Giardia in the intestinal tract. We designed three nonbiological surfaces with stagger arrangement manners and integrated them with a resistance microfluidic network to split Giardia-attaching forces ingeniously and developed the term "attaching contribution rate" (ACR) to describe their corresponding contributions. Our study shows that the total attaching force measured is 49.58 Pa, with three components being 22.66 Pa (suction force), 12.52 Pa (clutching force), and 14.4 Pa (combined electrostatic and van der Waals force), respectively, with ACRs being 46%, 25%, and 29%, respectively. By decomposing the attaching force and analyzing each force component and their structure and composition basis, whole profiles of the attachment mechanisms were revealed. Our method enables the analysis of the surface attachment mechanisms and their ACRs for Giardia.

Theoretical, experimental and numerical investigations on the energy absorption of splitting multiple circular tubes under impact loading

This paper presents an investigation into the energy absorption behaviour of splitting multiple circular tubes by theoretical, experimental and numerical methods. A theoretical solution for the steady-state crushing force of splitting multiple circular tubes is derived by applying the deformation theory. To explore the energy absorption of splitting multiple circular tubes and to validate the finite element model and a theoretical solution for the crushing force, an impact experiment is performed using a test trolley to examine the splitting process and force responses of multiple circular tubes. The finite element models of splitting multiple circular tubes are then established to investigate the energy absorption behaviour of the structure. The numerical simulation results agree well with those of the impact experiment. The energy absorption of splitting multiple circular tubes with different geometrical configurations, including the wall thickness of the tubes, number of tubes, radius of the tubes and conical angle of the dies, is analysed using a validated finite element model. The results show that the geometrical configurations of the tubes and conical angle of the dies have a distinct effect on the energy absorption. An analysis is also conducted to investigate the energy absorption by the evolution of the theoretical models. It is confirmed that the theoretical solutions provide a reliable prediction of the steady-state crushing force of splitting multiple circular tubes. The effect of the velocity is investigated, and the result shows that the steady-state force increased as the impact velocity increased.

Direct control method for improving stability and reliability of nonlinear stochastic dynamical systems

Optimal control for improving the stability and reliability of nonlinear stochastic dynamical systems is of great significance for enhancing system performances. However, it has not been adequately investigated because the evaluation indicators for stability (e.g. maximal Lyapunov exponent) and for reliability (e.g. mean first-passage time) cannot be explicitly expressed as the functions of system states. Here, a unified procedure is established to derive optimal control strategies for improving system stability and reliability, in which a physical intuition-inspired separation technique is adopted to split feedback control forces into conservative components and dissipative components, the stochastic averaging is then utilized to express the evaluation indicators of performances of controlled system, the optimal control strategies are finally derived by minimizing the performance indexes constituted by the sigmoid function of maximal Lyapunov exponent (for stability-based control)/the reciprocal of mean first-passage time (for reliability-based control), and the mean value of quadratic form of control force. The unified procedure converts the original functional extreme problem of optimal control into an extremum value problem of multivariable function which can be solved by optimization algorithms. A numerical example is worked out to illustrate the efficacy of the optimal control strategies for enhancing system performance.

High-Performance Fluorinated Fused-Ring Electron Acceptor with 3D Stacking and Exciton/Charge Transport.

A new fluorinated electron acceptor (FINIC) based on 6,6,12,12-tetrakis(3-fluoro-4-hexylphenyl)-indacenobis(dithieno[3,2-b;2',3'-d]thiophene) as the electron-donating central core and 5,6-difluoro-3-(1,1-dicyanomethylene)-1-indanone as the electron-deficient end groups is rationally designed and synthesized. FINIC shows similar absorption profile in dilute solution to the nonfluorinated analogue INIC. However, compared with INIC, FINIC film shows red-shifted absorption, down-shifted frontier molecular orbital energy levels, enhanced crystallinity, and more ordered molecular packing. Single-crystal structure data show that FINIC molecules pack into closer 3D "network" motif through H-bonding and π-π interaction, while INIC molecules pack into incompact "honeycomb" motif through only π-π stacking. Theoretical calculations reveal that FINIC has stronger electronic coupling and more molecular interactions than INIC. FINIC has higher electron mobilities in both horizontal and vertical directions than INIC. Moreover, FINIC and INIC support efficient 3D exciton transport. PBD-SF/FINIC blend has a larger driving force for exciton splitting, more efficient charge transfer and photoinduced charge generation. Finally, the organic solar cells based on PBD-SF/FINIC blend yield power conversion efficiency of 14.0%, far exceeding that of the PBD-SF/INIC-based devices (5.1%).

Que lindo o que vocês fizeram! - Brazilian Portuguese wh-exclamatives and the evidence for a split force

ABSTRACT Portuguese exhibits a great variety of wh-exclamative sentences, including sentential exclamatives, which are the main concern of this paper. Brazilian Portuguese sentential wh-exclamatives seem to provide evidence to propose a split Force in the periphery of the sentence (RIZZI, 1997) when one considers the cooccurrence of a relative and an exclamative in the same utterance. We assume there are at least two functional heads available in Force: a RelP (hosting relative WHs) and an ExclP, supposed to host exclamative WHs; analyzed data also show that exclamation must be higher than relativization in a Split Force projection, with some more place above ExclP for topicalizing other syntactic objects.

Effects of Chronic and Experimental Acute Masseter Pain on Precision Biting Behavior in Humans.

Chronic pain in the orofacial region is common worldwide. Pain seems to affect the jaw motor control. Hence, temporomandibular disorders (TMD) are often accompanied by pain upon chewing, restricted mouth opening and impaired maximal bite forces. However, little is known on the effects of pain, in particular the effects of chronic jaw muscle pain on precision biting. The aim of the study was to investigate the effect of chronic and acute jaw muscle pain on oral motor control during precision biting in humans. Eighteen patients with chronic masseter muscle pain and 18 healthy participants completed the experiment. All participants were examined according to the Diagnostic Criteria for TMD. Experimental acute pain was induced by bilateral, simultaneous sterile hypertonic saline infusions into the healthy masseter muscles. A standardized hold and split biting task was used to assess the precision biting. The data was analyzed with non-parametric statistical tests. The results showed no significant differences in the hold forces, split forces, durations of split or peak split rates within or between the pain and pain-free conditions. The mean split rate increased significantly compared to baseline values both in the chronic patients and the pain-free condition. However, this increase was not evident in the experimental acute pain condition. Further, there were no significant differences in the mean split rates between the conditions. The data suggest that jaw muscle pain does not seem to alter precision biting in humans, however, the possibility that a nociceptive modulation of spindle afferent activity might have occurred but compensated for cannot be ruled out.

Mechanics of direct bonding: Splitting forces

The bonding strength between dissimilar materials depends heavily on internal stresses, which arise due to the differences in the thermal expansion coefficients of the materials. While the existing models describe the splitting forces near the edges of the structure, those in the main part of the structure remote from the edges, where the stresses are uniformly distributed along the interface, have not been calculated yet. This study attempts to fill this knowledge gap in the mechanics of bonded structures. Herein, we propose a model that allows the calculation of the splitting forces in the basic part of the bonded bilayer where the internal stresses along interface are uniformly distributed. The calculations reveal three possible distributions of the splitting forces in the bonded structure, i.e., the splitting forces could be either located at the center or the periphery—which also includes the edges of the structure, or could be completely absent regardless of the total magnitude of the residual stresses. The results obtained could be used in bonding technology as an immediate guide to increasing the bonding strength between dissimilar materials.

Obreimoff revisited: Controlled heterogeneous fracture through the splitting of mica

Obreimoff reported his first instrumented measurements of the cleavage of muscovite mica in 1930 and that work helped to propel a greater understanding of fracture. This study builds upon that effort by investigating the role of compliance heterogeneities in brittle materials through mica splitting in a manner similar to Obreimoff. The natural layered structure of mica makes it ideal as a model system for studying fracture as crack propagation can be constrained along a single controlled cleavage plane. Cleavage through the insertion of a rounded wedge provides a straightforward mechanical setup that produces stable crack propagation, so long as the effects of friction and wedge geometry are properly considered. First, homogeneous mica sheets of uniform thickness are cleaved in ambient atmosphere to establish a baseline splitting force and critical strain energy release rate, similar Obreimoff’s original work. After establishing this baseline, mica sheets with prescribed thickness heterogeneities are investigated. It is found that the splitting force required to propagate a crack along a specimen with a sharp increase in layer thickness is significantly larger than the analogous homogeneous splitting forces, even though the crack is not deflected. This indicates that a sharp increase in stiffness can produce an increase in toughness in layered structures without the need for any actual toughness contrast between constituent components or any crack deflection. This toughening effect produced by compliance contrast may have implications in the context of layered ceramic composite design, where systems are often composed of a stiff outer shell and a more compliant and damage-tolerant functional layer.

Vibratory stimulus to the masseter muscle impairs the oral fine motor control during biting tasks

PurposeTo investigated the effect of vibratory stimulus on masseter muscles during oral fine motor biting tasks. MethodsSixteen healthy individuals (age: 24.5 ± 2.4 years) participated in experiment I during which the participants were asked to “hold and split” half a roasted peanut placed on a force transducer with their front teeth. The participant performed ten series with ten trials of the “hold and split” behavioral task while vibratory stimulus was applied on the masseter muscle every alternate series. Further, fourteen participants participated (age: 25.2 ± 4.8 years) in experiment II during which they performed a series each of the behavioral task at baseline, an adjusted baseline without and with vibration as well as with and without visual feedback. Hold and split forces along with the variability of hold force and duration and force rate during the split were measured. ResultsThe results of the study showed an increase in the magnitude of the hold force (P = 0.002), force rate during the split (P < 0.001) and a significant decrease in the duration of split (P < 0.001) due to the vibratory stimulus. However, there was no significant effect of the vibratory stimulus on the variability of hold forces (P = 0.879) or mean split force (P = 0.683) during the “hold and split” behavioral task. The results of experiment II also showed an increase in hold force due to the vibratory stimulus (P < 0.001). ConclusionsVibratory stimulus to the masseter muscles impairs the oral force control during a standardized biting task and provide further insight into the sensorimotor regulation of the masticatory system.

COMPUTER SIMULATION OF COMBINED SPLITTING FORCE: STRAIN LOADING OF DOUBLE-BEAM SAMPLES

The purpose of this work is to study possible schemes of loading double-cantilever beam (DCB) specimens to replenish the arsenal of the methods used in their testing. Mathematical analysis of ten different modes of specimen loading is carried out for different methods of immobilizing and loading of the cantilever including splitting force, deformational and combined loading. Analytical expressions for the stress intensity factor (SIF), as well as the dependence of the beam spread angle θ (rotation angle of the beam head) on the crack length are derived. Those dependences form a basis for developing the methods for measuring the dynamics of the crack length changes during testing. The energy approach is used in determination of the stress intensity factors. The classical scheme of force loading of the DCB specimen by a pair of forces is supplemented with a loading scheme with two pairs of forces applied to different cross sections. A modification of the DCB specimen by rigid binding of the ends of its consoles when each shoulder of the specimen is considered a singly statically indeterminable beam and DCB specimen becomes a double-beam specimen is also considered. The possibility of rearranging the sections of the load application and position of the rigid support-link is also studied. The deformational loading is simulated by inserting a wedge in one or two sites along the specimen length. The wedge effect is modeled by a preset deformation in one of the sections and binding of the specimen consoles in the other. Formulas of the stress intensity factor for the DCB specimen asymmetric with respect to the crack propagation line upon pure force loading by the forces applied in one section are presented. References to the reports on experimental implementation of a number of proposed and considered load configurations are presented.