Titanium may be considered a relatively new engineering material. It was discovered much later than the other commonly used metals, its commercial application starting in the late 1940s. Its usage as an implant material began in the 1960s, despite the fact that titanium exhibits superior corrosion resistance and tissue acceptance when compared with stainless steels and Cr-Co-based alloys. This paper reviews the use of titanium and titanium alloys for use in biomedical applications.

Review: titanium and titanium alloy applications in medicine

Many bodies, both solid and fluid, are capable of being stress-free in numerous configurations that are not related to each other through a rigid body motion. Moreover, it is possible that these bodies could have different material symmetries in these different stress-free “natural” configurations. In order to describe the response of such bodies, it is necessary to know the manner in which these “natural” configurations evolve as well as a class of response functions for the stress that are determined by kinematical quantities that are measured from these evolving natural configurations. In this review article, we provide a framework to describe the mechanics of such bodies whose “natural configurations” evolve during a thermodynamic process. The framework is capable of describing a variety of responses and has been used to describe traditional metal plasticity, twinning, traditional viscoelasticity of both solids and fluids, solid-to-solid phase transitions, polymer crystallization, response of multi-network polymers, and anisotropic liquids. The classical theories of elastic solids and viscous fluids are included as special cases of the framework. After a review of the salient features of the framework, we briefly discuss the status of viscoelasicity, traditional plasticity, twinning and solid to solid phase transitions within the context of the framework.

On the thermomechanics of materials that have multiple natural configurations Part I: Viscoelasticity and classical plasticity

Constitutive model for uniaxial transformation ratchetting of super-elastic NiTi shape memory alloy at room temperature

Large hysteresis loops are observed during cyclic loading–unloading of Mg and Mg–Zn alloys. This is true for both tension and compression cycling, for grain sizes between 25 and 670 μm, and for Zn contents between 0 and 6 mass%. The loops are ascribed to anelasticity resulting from elastic { 1 0 1 ¯ 2 } twinning. The anelastic strain increases with the strain and reaches a maximum at strains between about 1 and 2%. For a given total strain, the amount of anelastic strain increases with decreasing grain size, and decreases with increasing Zn content. The maximum observed anelastic strain is about 0.3% for pure Mg, decreasing with the solute content to about 0.2% for Mg–6 mass% Zn. The phenomenon is discussed in terms of the effect of solute content and grain size on the formation and stability of twins.

Reversible plastic strain during cyclic loading–unloading of Mg and Mg–Zn alloys

http://www-2.unipv.it/compmech/publications/2014_8.pdf

Theoretical and numerical modeling of shape memory alloys accounting for multiple phase transformations and martensite reorientation

In this work, a general inelastic framework for the derivation of general three-dimensional thermomechanical constitutive laws for materials undergoing phase transformations is proposed. The proposed framework is based on the generalized plasticity theory and on some basic elements from the theory of continuum damage mechanics. More specifically, a new elaborate formulation of generalized plasticity theory capable of accommodating the multiple and interacting loading mechanisms, which occur during the phase transformations, is developed. Furthermore, the stiffness variations occurring during phase transformations are taken into account by the proposed framework. For this purpose, the free energy is decomposed into elastic and inelastic parts, not in a conventional way, but in one which resembles the elastic-damage cases. Also, a rate-dependent version of the theory is provided. The concepts presented are applied for the derivation of a three-dimensional thermomechanical constitutive model for Shape Memory Alloy materials. Numerical simulations to show qualitatively the ability of the model to capture the behavior of the shape memory alloys are also presented. Furthermore, the model has been fitted to actual experimental results from the literature.

On the thermomechanical modeling of shape memory alloys

On the description of mechanisms with different characteristic times in solid materials: A non-conventional approach

Background: MBBS internship is the best year in the entire curriculum and the best thing that ever happens.

Aims and Objectives: (1) Evaluation of the quality of internship program provided to interns in Government Doon Medical College and Hospital and (2) to assess the level of satisfaction among interns related to their learning. 

Materials and Methods: The participants of this study were the batch 2016 cohorts of Government Doon Medical College, first batch who had completed their internship. A questionnaire containing multiple-choice answers was designed using Google Forms to assess their feedback. The questionnaire was allotted to the interns, by batch 2016 two MBBS graduates who completed their internship recently. The answers in Google Forms ticked were collected by them, and the data entered in an Excel sheet were represented in pie charts and bar charts and the average percentage was calculated for the degree of learning. A subjective assessment was made based on the findings. 

Results: All interns felt internship as useful. 52% of interns on average learned and acquired all the important skills in all the departments (medicine, surgery, obstetrics/gynecology, orthopedics, pediatrics, emergency, etc.), on average 40.8% were able to perform all the skills of every discipline seeking assistance, 17.6% learned all the skills but were not confident, and 9.8% of students learned nothing. 100% of interns learned all communication skills regarding doctor–patient interaction and ethical behavior among colleagues, seniors, and paramedical staff. 

Conclusion: Internship program in Government Doon Medical College and Hospital provides lucrative learning to young interns. Majority of interns felt satisfied with the internship, but some improvements can also be done to cover the lack.

Evaluation of quality of internship program and medical interns’ satisfaction in internship course by taking feedback from interns by written questionnaire method in Government Doon Medical College and Hospital, Dehradun

S. Bahuguna

Papers

On the thermomechanical modeling of shape memory alloys

On the description of mechanisms with different characteristic times in solid materials: A non-conventional approach

Evaluation of quality of internship program and medical interns’ satisfaction in internship course by taking feedback from interns by written questionnaire method in Government Doon Medical College and Hospital, Dehradun

Evaluation of pattern of prescribing of antimicrobials in Government Doon Hospital and assessment of their rational use