The important task in experimental biomechanics is the measurement of displacement and strain in the bone tissues

The important task in experimental biomechanics is the measurement of displacement and strain in the bone tissues. Formerly, the main source of measuring the strain in soft tissues 1-2 and hard tissues 3 is by using strain gauges and extensometers. However, gauges intermittently are too large when compared to the scale at which strains gradients are evaluated in tissues 4-5. The extensometers sometime can induce µdamage in bone. When computational methods considered, especially finite element (FE) analysis they completely relies on experimental data as an input as well as result validation. Therefore, the very alternative is measurement techniques such as Digital volume approach (DVC) and Digital Image Correlation (DIC). Palanca M et al *6 described the potentialities and limitations of digital image correlation DIC in the biomechanical field. Despite many advantages of using DIC like full-filed measurement of displacement/strain, any size and location of the specimen, both small and large deformation etc. in the biomechanical field. DIC is limited for surface measurements only. In such predicament, Digital volume correlation (DVC) has emerged as an innovative and elite method for full volume displacement and strain measurement in biomechanics field.
In 1999 Bay et al 7 coined digital volume correlation (DVC) method, a three-dimensional (3D) technique able to measure mechanical fields in the volume and not limited to the sample surface. Ever since then the usage of DVC has evolved exponentially in the biomechanics field. With the advancements in the computer tomography imaging and growth in computer performances numerous DVC methods have been proposed 8-12 for measuring strain and displacement fields in bone tissues. Robert B et al 13* provided an overview of the development of DVC method in bone tissues displacement and strain measurement errors in terms of accuracy and precision. Palanca et al 14* compared limitation of different DVC approach in terms of sub volume size, accuracy and computational cost for high-resolution data.
Despite the rapid development of DVC in the biomechanics field, DVC presents some limitations to perform accurate measurements in bone tissues to detect local behaviour linked to mechanical effects involved at the micro scale.
One possible solution could be to add more measurement points in DVC to obtain a high-resolution analysis. When the measurement points increase, the computational cost increases and become tedious 15*. Therefore, in the present study a particular kinematical transformation model based on Heaviside’s function hereinafter referred to as Heaviside-based Digital Volume Correlation (H-DVC) is used. The work conferred here aims to address the following objectives.
? Application of this novel method (H-DVC) to the case of cancellous bone tissues for identifying the local displacement fields and µstrain localization.
? Evaluation and measurement of local displacement and stain localization in bone tissues using classical DVC and proposed H-DVC method using parallelized computation.
? Finally, an attempt made to compute fracture volume (FV/TV) parameter to evaluate the fracture in cancellous bone using classical DVC and H-DVC method to demonstrate the effectiveness of the H-DVC method over classical method.