Hill Criteria Research Articles

Matrix failures effect on damage evolution of particle reinforced composites

This article presents a micromechanics model to investigate matrix damage evolutions of the particle-reinforced composites (PRCs), as well as matrix failures effect on the stiffness degradation. Compared with the finite-element results and experiment data, it is indicated that the developed micromechanics model can be employed to effectively predict the mechanical behaviors of PRCs. The microscopic three-dimensional stress field distribution is investigated on the basis of the stress concentration region to capture the initial damage behavior of the representative volume element. Moreover, the failure criteria of Hill, Tsai-Wu and maximum stress are incorporated into the proposed micromechanics model to investigate the stiffness reduction properties of PRCs subjected to a uniaxial tensile loading. The microstructure near the interface is further refined to slow down the rapid deterioration around stress concentration regions. The results revealed that the stiffness degradation of matrix significantly affects macroscopic mechanical properties of the PRCs.

A Graphical Method to Estimate Forming Limit Curve of Sheet Metals

Since its foundation, the concept of forming limit diagram has been widely accepted in sheet metal forming community as a powerful tool for studying formability. There are pyramid models that were developed to estimate the forming limit curve theoretically, for example, Swift's diffuse necking criterion, Hill's localized necking criterion, Marciniak and Kuczynski model, Modified Maximum Force Criterion, etc.. Implement of these models, however, is a laborious task. To simply the task, this study presents a graphical method to estimate forming limit curve of sheet metal. Some new insights into the Modified Maximum Force Criterion, the Hora method, are discussed. The insights pertain to the use of a graphic tool to estimate limit strains at three critical forming modes in sheet metal forming that are the uniaxial tension, plane strain, and equi-biaxial tension. Connecting three points by linear lines yields to a simple graph of forming limit curve. Method validation is supported by comparing the estimated forming limit curve with experimentally measured data for several automotive sheet metals.

A Theory of Autofrettage for Open-Ended, Polar Orthotropic Cylinders

Autofrettage is a widely used process to enhance the fatigue life of holes. In the theoretical investigation presented in this article, a semi-analytic solution is derived for a polar, orthotropic, open-ended cylinder subjected to internal pressure, followed by unloading. Numerical techniques are only necessary to solve a linear differential equation and evaluate ordinary integrals. The generalized Hooke’s law connects the elastic portion of strain and stress. The flow theory of plasticity is employed. Plastic yielding is controlled by the Tsai–Hill yield criterion and its associated flow rule. It is shown that using the strain rate compatibility equation facilitates the solution. The general solution takes into account that elastic and plastic properties can be anisotropic. An illustrative example demonstrates the effect of plastic anisotropy on the distribution of stresses and strains, including residual stresses and strain, for elastically isotropic materials.

The Precautionary Principle Meets the Hill Criteria of Causation

ABSTRACTThis article examines the relationship between the precautionary principle and the well-known Hill criteria of causation. Some have charged that the Hill criteria are anti-precautionary because they are strongly inclined towards false negatives in multi-causal contexts typical of environmental and public health issues. However, we argue that without guidance on how to interpret and weight the criteria, no such claims can be supported. Using a case study of tuberculosis among South African goldmine workers, we consider the implications of different weightings of the Hill criteria and how they might be appropriate depending on the stakes of error.

Dynamic Mechanical Properties of Russian Pinus sylvestris var. mongolica Litv: Experimental and Numerical Simulation

With the Split Hopkinson Pressure Bar (SHPB) experiment and numerical simulation on Russian Pinus sylvestris var. mongolica Litv carried out, the dynamic mechanical properties of the pine wood at high strain rates were researched, and the relevant constitutive models was analyzed. The experiment results suggested that the dynamic mechanical properties of the pine wood were affected by strain rates and wood directions. The stress-strain relationship was mainly influenced by wood directions, but the initial yield stress was related to strain rates and wood directions. When the load was along the straight grain direction, fracture behaviors were caused by shear damage and fiber tensile fracture. The specimens were broken into ‘crushed’ pieces because of fiber and lignin separation, and fiber kink. However, it was chief role for the fracture in transverse grain direction that failure cracks grew down fiber. The dynamic responses described with model based on improved Hashin failure criterion were consistent with actual results, compared with model based on the Hill yield criterion. Related research work provides a certain reference for the related problems research and engineering practice application of Russian Pinus sylvestris var. mongolica Litv.

Three-dimensional yielding in anisotropic materials: validation of Hill's criterion.

Yielding transition in isotropic soft materials under the superposition of orthogonal deformation fields is known to follow von Mises' criterion. However, in anisotropic soft materials, von Mises' criterion fails owing to the preferred directions associated with the system. In this work we study a model anisotropic yield stress system: electrorheological (ER) fluids which show structural formation in the direction of an electric field. We subject the ER fluids to the superposition of orthogonal stress fields which leads to different yield stress values. We obtain a yielding state diagram by plotting the normalized rotational shear stress against the normalized radial shear stress corresponding to a yield point for a given electric field. Remarkably, the state diagram validates the Hill yielding criterion, which is a general yielding criterion for materials with anisotropy along three orthogonal directions, originally developed for metallic systems. Validation of Hill's criterion suggests the universality of its application in anisotropic systems including conventional anisotropic soft materials having yield stress.

Simulation approach for three-point plastic bending of additively manufactured Hastelloy X sheets

Abstract Additive manufacturing as a process for producing semi-finished parts for a subsequent forming operation has not been investigated yet. This paper examines the forming behavior of an additively manufactured monolithic sheet metal in three point bending. An approach for a numerical simulation is proposed, with the results of the material characterization of additively manufactured Hastelloy X. The anisotropic behavior is implemented with the Hill (1948) yield criterion. The results reveal that it is possible to characterize an additively manufactured material employing testing procedures commonly used in forming technologies and to use the material properties and flow curves to numerically simulate a bending operation with a difference of not more than 4 % compared to the experiment.

Activation of TRPA1 by volatile organic chemicals leading to sensory irritation.

Many volatile organic chemicals (VOCs) have not been tested for sensory pulmonary irritation. Development of in vitro non-animal sensory irritation assay suitable for a large number of chemicals is needed to replace the mouse assay. An adverse outcome pathway (AOP) is designed to provide a clear description of the biochemical and cellular processes leading to toxicological effects or an adverse outcome. The AOP for chemical sensory pulmonary irritation was developed according to the Organization for Economic Co-operation and Development guidance including the Bradford Hill criteria for a weight of evidence to determine the confidence of the AOP. The proposed AOP is based on an in-depth review of the relevant scientific literature to identify the initial molecular event for respiratory irritation. The activation of TRPA1 receptor (transient receptor potential cation channel, subfamily A, member 1) is the molecular initial event (MIE) leading to sensory irritation. A direct measure of TRPA1 activation in vitro should identify chemical sensory irritants and provide an estimate of potency. Fibroblasts expressing TRPA1 are used to determine TRPA1 activation and irritant potency. We report a linear relationship between the in vivo RD₅₀ and the in vitro pEC₅₀ values (R=0.81) to support this hypothesis. We propose that this in vitro assay after additional analysis and validation could serve as a suitable candidate to replace the mouse sensory irritation assay.

Про вплив анізотропії матеріалу на граничний стан ортотропної пластини з періодичною системою колінеарних тріщин під дією двовісного навантаження

In the presented paper, the limiting state of the orthotropic plates weakened by the periodic system of collinear cracks under biaxial external loading is studied on the basis of the modified crack model of the Leonov-Panasyuk-Dagdale. The material of plate satisfies the strength condition of the general form. On the basis of the solution of a similar problem for an orthotropic plate with one crack, we obtain the relations for determining the basic parameters of a crack model, such as the size of the process zones, the stresses in these zones, and the opening at the top of the cracks. The criterion of critical crack opening is selected as a fracture criterion. On the example of a material satisfying Hoffman strength criterion (generalization of the Mises–Hill criterion, which takes into account the dependence of the difference between the tensile and compressive strength of unidirectional composite materials), the fracture mechanism of a plate weakened by the periodic system of collinear cracks was investigated. The influence of the degree of material anisotropy and biaxiality of external loading on the fracture process and the limiting state of the plate are shown.

Management options for low-dose methotrexate-induced oral ulcers: A systematic review.

BackgroundOral ulcers caused by methotrexate (MTX) at low doses are a known side effect of this drug. Although increasingly more patients are medicated with MTX, these painful ulcers, without traumatic origin and resistant to any type of treatment, are not usually identified by health professionals as a side effect of the medication.Material and MethodsIn the absence of a consensus protocol for the effective treatment of oral lesions produced by MTX, the objective of this article was to review and analyse the information from articles related to oral ulcers produced by low-dose MTX and to record the clinical management performed and the MTX dose given to the patient. Data sources - Medline, Web of Science, and Cochrane Library. Participants - Patients treated with low-dose MTX (less than 25 mg/week). Interventions - Management of oral lesions caused by MTX. Study eligibility criterion, study appraisal and synthesis method: An initial search was carried out in the aforementioned databases with the terms ‘methotrexate AND oral OR ulcer’. The search was carried out using both medical subject heading (MeSH) terms and a free search between January 2003 and January 2018. Of the results obtained, two independent researchers analysed abstracts that met the search criteria, that is, those that mentioned oral ulcers produced by MTX at low doses. Next, both researchers read the complete article and determined whether it met the following inclusion criteria: written in English, specified the dose of MTX prescribed for the patient and specified the protocol of action for the ulcers. A third investigator acted as a mediator in cases of dispute. Agreement was calculated using Cohen’s kappa coefficient, with a k value of 0.82. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guide for systematic reviews was used.ResultsThe initial search resulted in a total of 66 articles, of which 30 were selected to assess their inclusion in this study. Finally, 16 met the inclusion criteria. Using the Pierson and Newcastle-Ottawa scales and Bradford Hill criteria modified for studies of case series and “in relation to a case”, 2 were rated as high quality, 2 were rated as low quality and 12 were rated as medium quality. The limitations of this study are based on the fact that all of the articles available to carry out the systematic review were “in relation to a case or series of cases”, with the heterogeneity of data that this implies.ConclusionsEvidence on the management of oral ulcers in the oral cavity produced by MTX at low doses is scarce due to the heterogeneity of data and the measures adopted in the selected studies. Therefore, it seems that this management is relegated to the perception of the clinician rather than to a specific protocol of action. Studies with a longer follow-up duration and larger sample size are needed to guide different health professionals on the management of these lesions. Key words:Methotrexate, Oral ulcers, Low-dose methotrexate.

Herpes Simplex Virus Type-1 Infection: Associations with Inflammation and Cognitive Aging in Relation to Schizophrenia.

Most persons experience cognitive decline as they grow older. The term "cognitive aging," coined to describe milder varieties of cognitive decline, is likely to be due to multiple causes. Persistent or repeated infections of the central nervous system (whether subclinical or diagnosable) can cause damage to neurons directly or indirectly through inflammation resulting in incremental neuronal damage, thus eroding cognitive reserve. This possibility has not been considered widely. We evaluated the data linking persistent infection with herpes simplex virus type 1 (HSV-1) and cognitive aging by applying the Bradford Hill criteria. Despite inherent problems in establishing causal relations for chronic disorders, our analyses suggest plausible links. These studies are pertinent for patients with schizophrenia, who are particularly vulnerable due to disorder-related cognitive impairment. Further investigations are warranted to test a causal hypothesis, particularly prospective studies and intervention studies.

Migraine Progression: A Systematic Review

Migraine is a common and often debilitating neurological disease. It can be divided into episodic and chronic subforms based on the number of monthly headache days. Because only a subset of individuals with episodic migraine (EM) progress to chronic migraine (CM) over any given time period, understanding the factors that predict the new onset of CM or "migraine progression" may provide insights into the mechanisms, pathophysiology, prevention, and treatment of CM. In this review, we identify and summarize studies that report risk factors associated with the new onset of CM or related chronic headache diagnoses, group these risk factors and report the strength of evidence for the identified risk factors. To conduct a systematic review of studies that identify risk factors for the new onset of CM or related chronic headache diagnoses such as transformed migraine (TM) and chronic daily headache (CDH). Herein we summarize the findings of studies of risk factors associated with the new onset of CM/TM, CDH, or related diagnoses from the English language literature published before March 2018. The PubMed database was searched for relevant studies. Longitudinal studies with follow-up data and case-control studies were included in this qualitative synthesis. We report methodology, analytic criteria, and results for each manuscript and for the parent study. Next, we review the strength of evidence for each of the identified risk factors using a modified version of AB Hill's criteria for causation and rank evidence as fair, moderate, or strong. We categorized risk factors as nonmodifiable, modifiable and based on putative mechanisms. We further categorized risk factors into sociodemographics, lifestyle factors and habits, headache features, comorbid and concomitant diseases and conditions and pharmacologic treatment-related. Finally, we review theories of the pathophysiology underlying the development of new onset chronic migraine or increasing attack frequency. The PubMed search yielded 1870 records after duplicates were removed. Nine additional records were identified through expert consultation and other methods (eg, citations found as references in manuscripts identified in the literature review and through communication with the authors of manuscripts included in the review). The 1879 manuscripts were screened against the inclusion and exclusion criteria and 109 were found to be potentially eligible. Of 109 full-text articles, 17 studies were identified as meeting the prespecified criteria based on the consensus of all authors. Of the 17 full texts, 13 were longitudinal cohort studies and 4 were case-controlled studies. We found strength of evidence ranging from fair to strong for the identified risk factors. The strongest data were found for increased headache day frequency, depression, and medication overuse/high-frequency use. Risk factors for new onset CM and CDH in children and adolescents were similar to those identified in adults. A range of risk factors for the new onset of CM/TM, CDH, or related chronic headache diseases were identified with the strongest data supporting increased headache day frequency, acute medication overuse/high-frequency use and depression, which are potentially modifiable risk factors. Modifiable risk factors may provide targets for intervention. The lack of strong evidence or any evidence does not imply that there is not a relationship between a particular risk factor and new onset CM or related disease; but may indicate little or no research or that research did not have sufficient methodological rigor. In addition, it is likely that additional risk factors exist which have not yet been identified. Putative factors include pro-inflammatory states and pro-thrombotic states. Development of central sensitization and increased activation of the trigeminal nociceptive pathways may be drivers of the new onset of CM or CDH. Future research may include the systematic testing of interventions targeting modifiable risk factors to determine if progression can be prevented as well as continued exploration of the benefits of treating these risk factors among people with CM in an effort to increase rates of remission. Future work should also consider the natural fluctuations in headache day frequency and examine progression in terms of continuous definitions rather than or in addition to a dichotomous boundary.

Web of Causation between Dietary Patterns and Childhood Obesity: Applying Hill's Criteria

Abstract Since their publication in 1965, the Bradford Hill criteria for causality have been largely used as a framework for causal inference in epidemiology. We aim at employing this classical approach to shed new light onto the web of causation of childhood obesity. Although the fundamental cause of obesity is the long-term imbalance between energetic need and intake, this medical condition is multifactorial in its origin, influenced by genetic, behavioral, socioeconomic, and environmental factors. This imbalance leads to accumulation of excessive adipose tissue. Observational studies tend to mostly quantify association between dietary factors and accumulation of adipose tissue. On the other hand, multivariate analysis proved some of these associations to be spurious, therefore prospective trials are needed to demonstrate causality. Short term experimental studies have been conducted to identify unique dietary pattern changes on specific outcomes, but long term, community-based studies would offer more comprehensive answers on dietary pattern effects. We conducted a literature review on PubMed, Scopus, Web of Science, and Google Scholar. From a total of 323 papers identified at first stage, we further discuss the applicability of Bradford Hill criteria for 31 articles, by examples of dietary patterns and accumulation of excess body fat as exposure-response associations. We also put forward and analyzed the evidence prospective studies would bring, as foundation for future interventions.

Evidence of a Causal Relationship Between Smoking Tobacco and Schizophrenia Spectrum Disorders.

There has been emerging evidence of an association between tobacco smoking and schizophrenia spectrum disorders (SSD). Two meta-analyses have reported that people who smoke tobacco have an ~2-fold increased risk of incident schizophrenia or psychosis, even after adjusting for confounding factors. This study aimed to critically appraise the research which has examined the association between tobacco smoking and SSD against the Bradford Hill criteria for causality, to determine the strength of the evidence for a causal relationship. Eight longitudinal studies (seven cohort studies and one case control study) were identified which examined tobacco smoking as an exposure and psychosis as an outcome. All seven cohort studies were assessed as being of high quality using the Newcastle-Ottawa Scale. Six of the eight studies found a statistically significant positive association between tobacco smoking and onset of SSD. These studies reported a consistent association with a moderate to large effect size and a dose response relationship. The studies adjusted for multiple potential confounders including age, sex, socioeconomic status, shared genetic risk, prodromal symptoms, and comorbid cannabis and other substance use. The studies did not adjust for exposure to childhood trauma or prenatal tobacco. There was substantial though inconclusive evidence supporting a causal relationship between tobacco smoking and increased risk of SSD. If a causal relationship does exist, nicotine is most likely responsible for this association. This raises serious public health concerns about the increasing use of e-cigarettes and other products, particularly by adolescents whose nicotine use may increase their risk of SSD. Research is urgently needed to examine the association between e-cigarette use and incident psychosis, particularly in adolescents and young adults.

LDL-C does not cause cardiovascular disease: a comprehensive review of the current literature

ABSTRACTIntroduction: For half a century, a high level of total cholesterol (TC) or low-density lipoprotein cholesterol (LDL-C) has been considered to be the major cause of atherosclerosis and cardiovascular disease (CVD), and statin treatment has been widely promoted for cardiovascular prevention. However, there is an increasing understanding that the mechanisms are more complicated and that statin treatment, in particular when used as primary prevention, is of doubtful benefit.Areas covered: The authors of three large reviews recently published by statin advocates have attempted to validate the current dogma. This article delineates the serious errors in these three reviews as well as other obvious falsifications of the cholesterol hypothesis.Expert commentary: Our search for falsifications of the cholesterol hypothesis confirms that it is unable to satisfy any of the Bradford Hill criteria for causality and that the conclusions of the authors of the three reviews are based on misleading statistics, exclusion of unsuccessful trials and by ignoring numerous contradictory observations.

Unravelling the hip pistol grip/cam deformity: Origins to joint degeneration

This article reviews a body of work performed by the investigators over 9 years that has addressed the significance of cam morphology in the development of hip osteoarthritis (OA). Early hip joint degeneration is a common clinical presentation and preexisting abnormal joint morphology is a risk factor for its development. Interrogating Hill's criteria, we tested whether cam-type femoroacetabular impingement leads to hip OA. Strength of association was identified between cam morphology, reduced range-of-movement, hip pain, and cartilage degeneration. By studying a pediatric population, we were able to characterize the temporality between cam morphology (occurring 1st) and joint degeneration. Using in silico (finite element) and in vivo (imaging biomarkers) studies, we demonstrated the biological plausibility of how a cam deformity can lead to joint degeneration. Furthermore, we were able to show a biological gradient between degree of cam deformity and extent of articular damage. However, not all patients develop joint degeneration and we were able to characterize which factors contribute to this (specificity). Lastly, we were able to show that by removing the cam morphology, one could positively influence the degenerative process (experiment). The findings of this body of work show consistency and coherence with the literature. Furthermore, they illustrate how cam morphology can lead to early joint degeneration analogous to SCFE, dysplasia, and joint mal-reduction post-injury. The findings of this study open new avenues on the association between cam morphology and OA including recommendations for the study, screening, follow-up, and assessment (patient-specific) of individuals with cam morphology in order to prevent early joint degeneration. Statement of significance: By satisfying Hill's criteria, one can deduct that in some individuals, cam morphology is a cause of OA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3125-3135, 2018.

What is cold-related mortality? A multi-disciplinary perspective to inform climate change impact assessments

BackgroundThere is a growing discussion regarding the mortality burdens of hot and cold weather and how the balance between these may alter as a result of climate change. Net effects of climate change are often presented, and in some settings these may suggest that reductions in cold-related mortality will outweigh increases in heat-related mortality. However, key to these discussions is that the magnitude of temperature-related mortality is wholly sensitive to the placement of the temperature threshold above or below which effects are modelled. For cold exposure especially, where threshold effects are often ill-defined, choices in threshold placement have varied widely between published studies, even within the same location. Despite this, there is little discussion around appropriate threshold selection and whether reported associations reflect true causal relationships – i.e. whether all deaths occurring below a given temperature threshold can be regarded as cold-related and are therefore likely to decrease as climate warms. ObjectivesOur objectives are to initiate a discussion around the importance of threshold placement and examine evidence for causality across the full range of temperatures used to quantify cold-related mortality. We examine whether understanding causal mechanisms can inform threshold selection, the interpretation of current and future cold-related health burdens and their use in policy formation. MethodsUsing Greater London data as an example, we first illustrate the sensitivity of cold related mortality to threshold selection. Using the Bradford Hill criteria as a framework, we then integrate knowledge and evidence from multiple disciplines and areas- including animal and human physiology, epidemiology, biomarker studies and population level studies. This allows for discussion of several possible direct and indirect causal mechanisms operating across the range of ‘cold’ temperatures and lag periods used in health impact studies, and whether this in turn can inform appropriate threshold placement. ResultsEvidence from a range of disciplines appears to support a causal relationship for cold across a range of temperatures and lag periods, although there is more consistent evidence for a causal effect at more extreme temperatures. It is plausible that ‘direct’ mechanisms for cold mortality are likely to occur at lower temperatures and ‘indirect’ mechanisms (e.g. via increased spread of infection) may occur at milder temperatures. ConclusionsSeparating the effects of ‘extreme’ and ‘moderate’ cold (e.g. temperatures between approximately 8–9 °C and 18 °C in the UK) could help the interpretation of studies quoting attributable mortality burdens. However there remains the general dilemma of whether it is better to use a lower cold threshold below which we are more certain of a causal relationship, but at the risk of under-estimating deaths attributable to cold.

Analytical solution for limit load of orthotropic pressure pipe with internal circumferential crack

Based on the Hill yield criterion, considering three directional stress (r, θ, z) of pressure pipe, the analytical solution for limit load of orthotropic pressure pipe with constant-depth internal circumferential crack under combined pressure, axial force and bending has been derived. The effect of crack size, anisotropy of pipe material, load (pressure, moment), and pipe size on the limit load of orthotropic pressure pipe is discussed. The results show that it is necessary to consider three directional stress for thick-walled pipe, and the influence of radial stress on the limit load cannot be ignored for thick-walled pipe. The limit load of pipe with constant-depth internal circumferential crack decreases with crack size. The limit load of pipe under pure bending is only related to axial yield strength. The limit load of pipe under pure internal pressure is mainly determined by circumferential yield strength.

The pertussis hypothesis: Bordetella pertussis colonization in the etiology of asthma and diseases of allergic sensitization

Decades of peer reviewed evidence demonstrate that: 1)Bordetellapertussisand pertussis toxin are potent adjuvants, inducing asthma and allergic sensitization in animal models of human disease, 2)Bordetella pertussisoften colonizes the human nasopharynx, and is well documented in highly pertussis-vaccinated populations and 3) in children, a history of whooping cough increases the risk of asthma and allergic sensitization disease. We build on these observations with six case studies and offer a pertussis-based explanation for the rapid rise in allergic disease in former East Germany following the fall of the Berlin Wall; the current asthma, peanut allergy, and anaphylaxis epidemics in the United States; the correlation between the risk of asthma and gross national income per capita by country; the lower risk of asthma and allergy in children raised on farms; and the reduced risk of atopy with increased family size and later sibling birth order. To organize the evidence for the pertussis hypothesis, we apply the Bradford Hill criteria to the association between Bordetella pertussisand asthma and allergicsensitization disease. We propose that, contrary to conventional wisdom that nasopharyngealBordetella pertussiscolonizing infections are harmless, subclinicalBordetella pertussiscolonization is an important cause of asthma and diseases of allergic sensitization.

A novel analytical model to predict springback of DP780 steel based on modified Yoshida-Uemori two-surface hardening model

Advanced high strength steels are widely used in the automotive industry due to their appropriate strength to weight ratio. This alloy has unique hardening behavior. In this paper, a novel analytical model is introduced to predict springback in U-shaped bending process of as-received and pre-strained DP780 dual phase steel specimens. This model is based on the Hill48 yield criterion and plane -strain condition. The effect of sheet thinning and the motion of the neutral surface is taken into account on the springback. The modified Yoshida-Uemori two surface hardening model is applied to investigate the effect of work hardening stagnation. This novel model is examined on the Numisheet 2011 benchmark 4. The effects of the blank holder force and work hardening stagnation are studied on the sheet springback phenomenon. By comparison of the present model with previous alternate models, obtaining the more accuracy is tangible. Also, it is demonstrated that the springback parameters have more changes with increasing the blank holder force. Also, the parameter of the work hardening stagnation has more effect on the pre-strained specimen as compared to the as-received sample.