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Finite element models of wood baseball bats are a valuable tool to explore the relationship between bat profile and bat durability. However, for such finite element models to be credible, the material models must capture the mechanical response of the wood under consideration. In the current research, a comprehensive experimental program was conducted to characterize the mechanical behavior of maple and ash woods for the range of densities used to make major-league quality baseball bats. The test program included (1) four-point bend testing to determine elastic moduli and strength and (2) Charpy testing to determine strain to failure as a function of strain rate and wood density. The material parameters were subsequently calibrated by completing finite element simulations of the Charpy tests in LS-DYNA using the MAT_WOOD material model. This paper describes the experimental characterization program used to determine material parameters of maple and ash wood species for use in finite element simulations of wood baseball bats.

In a response to reverse the trend of a perceived increase in multi-piece failures (MPFs) of wood baseball bats in Major League baseball games, the Office of the Commissioner of Baseball implemented changes to the Wooden Baseball Bat Specifications (WBBS) in December 2008. These changes introduced bat-supplier regulations that outlined strict quantitative requirements for wood quality and instituted a third-party inspection of professional wooden baseball bats for the 2009 season. Additional changes to the WBBS for the 2010, 2011, and 2012 seasons targeted increasing the density of the wood used to make maple bats, thereby increasing the minimum breaking strength of the wood allowed for these bats. By the completion of the 2014 season, these changes had driven a 65% reduction in the rate of MPFs per game relative to the 2008 season. It is hypothesized that the rate of MPFs can be further reduced if regulations on the allowable geometries of the taper region for the bats used by MLB teams are implemented. To develop a fundamental understanding of the relationship among (1) the angle of the taper (2) the starting point of the taper along the length of the bat, and (3) wood density, a series of generic bat profiles that were subjected to bat/ball impacts was investigated using LS-DYNA. In this paper, the results of these bat/ball impact simulations are shared, and a summary of the various combinations of these geometric parameters on bat stress and strain is presented. The durability information gained from these generic bat profiles is then used to give guidance in understanding why certain bat profiles used in professional baseball have relatively high rates of MPFs while other profiles exhibit a relatively low rate of MPFs.

Major League Baseball (MLB) currently has few restrictions on the bat profiles allowed for use during gameplay. Although current multi-piece failure (MPF) rates are at their lowest in years, there is still room for further improvement by regulating the bat profiles allowed in games. The influence of bat profile tapering was analyzed utilizing finite element models of various known profile geometries to determine the effect on bat durability. LS-DYNA simulations were processed for profiles over a range of maple wood densities that would be currently allowed by MLB regulations. This paper will describe the various modelling studies conducted to determine the factors that comprise a bat profile of good durability. The results of the modelling are compared to on-field data of bat failures during gameplay of known profiles used by MLB players. A profile scoring formula is proposed that is a combination of bat geometrical characteristics and bat wood density. This score is shown to be a good predictor of the relative durability of a given set of bat configurations.

The bats used in Major League Baseball (MLB) are required to be turned from a single piece of wood. Northern white ash had been the wood of choice until the introduction of hard maple in the late 1990s. Since the introduction of maple to the game, there was a perceived increase in the rate of bats to exhibit multiple piece failures (MPF)—both ash and maple. These failures introduced a new aspect to the game that can be a significant factor during play, i.e. pieces of bats going into the field of play, thereby distracting fielders while reacting to the batted ball. Observations of bat breakage in the field and lab testing of bats in controlled conditions have shown the bat durability is a function of wood quality and bat profile. Wood quality is described by the density and the slope of grain of the wood used in the bat. The density and the slope of grain determine the effective strength of the wood. The bat profile is described by the variation in the diameter of the bat along its length. The wood densities and bat profiles which are preferred by players, are typically in direct contradiction with what makes for a durable bat. In this paper, the finite element method is used to develop calibrated models of the breaking of wood bats in controlled lab conditions. The modeling approach is then used to explore how bat profile influences bat durability and what potential changes can be made in bat profile to satisfy player desires while increasing bat durability.

Yield analysis is a crucial task during project deployment of solar thermal power plants. Currently, many different modeling approaches and computer tools for yield analysis are used. Within the SolarPACES project guiSmo, aiming at the development of guidelines for the annual yield prediction of solar thermal power plants, relevant effects for the steady-state modeling of plant sub-systems have been identified [1] . The target of the ongoing project phase is the development of general definitions for all relevant effects. Furthermore, suitable modeling approaches have to be identified and described unambiguously. For every effect, the impact on the predicted electricity yield is estimated in order to assess the significance of the considered effect. Since the most significant effects have to be considered in a subsequent uncertainty analysis, reasonable model and parameter uncertainties have to be defined, too. Finally, default model parameter for state-of-the-art components or subsystems will be edited. Beside the present status of the project, this paper presents investigations on the effects of the optical losses of the sub-system collector field on the annual yield. These effects are namely the peak optical efficiency, incidence angle modifier (IAM), shading and end losses. For each effect, a precise definition is presented and relevant modeling approaches are identified and their pros and cons are discussed. To investigate the influence of these effects, a reference solar thermal power plant with parabolic troughs is defined. The annual yield is simulated for this reference system investigating the identified modeling approaches and assessing their significance.

Bat durability is defined as the relative bat/ball speed that results in bat breakage, i.e., the higher the speed required to initiate bat cracking, the better the durability. In 2008, Major League Baseball added a regulation to the Wooden Baseball Bat Standards concerning Slope-of-Grain (SoG), defined to be the angle of the grain of the wood in the bat with respect to a line parallel to the longitudinal axis of the bat, as part of an overall strategy to reverse what was perceived to be an increasing rate of wood bats breaking into multiple pieces during games. The combination of a set of regulations concerning wood density, prescribed hitting surface, and SoG led to a 30% reduction in the rate of multi-piece failures. In an effort to develop a fundamental understanding of how changes in the SoG impact the resulting bat durability, a popular professional bat profile was examined using the finite element method in a parametric study to quantify the relationship between SoG and bat durability. The parametric study was completed for a span of combinations of wood SoGs, wood species (ash, maple, and yellow birch), inside-pitch and outside-pitch impact locations, and bat/ball impact speeds ranging from 90 to 180 mph (145 to 290 kph). The *MAT_WOOD (MAT_143) material model in LS-DYNA was used for implementing the wood material behavior in the finite element models. A strain-to-failure criterion was also used in the *MAT_ADD_EROSION option to capture the initiation point and subsequent crack propagation as the wood breaks. Differences among the durability responses of the three wood species are presented and discussed. Maple is concluded to be the most likely of the three wood species to result in a Multi-Piece Failure. The finite element models show that while a 0&deg, SoG bat is not necessarily the most durable configuration, it is the most versatile with respect to bat durability. This study is the first comprehensive numerical investigation as to the relationship between SoG and bat durability. Before this numerical study, only limited empirical data from bats broken during games were available to imply a qualitative relationship between SoG and bat durability. This novel study can serve as the basis for developing future parametric studies using finite element modeling to explore a large set of bat profiles and thereby to develop a deeper fundamental understanding of the relationship among bat profile, wood species, wood SoG, wood density, and on-field durability.

With the success of CSP technology in the last years more players are active in the market, inducing the need for harmonization of technical terms and methodologies. The mission of the SolarPACES “guiSmo” project which was started in 2010 is to develop a guideline for CSP yield analysis [1]. Activities carried out so far have shown that people have different understandings of many terms used in daily CSP practice. Especially for the development of guidelines, the essential terms need to be clearly defined in order to avoid inconsistencies within the same project. A first version of a nomenclature has been compiled by the “guiSmo” team and will undergo final discussion. The aim is to come to a harmonized version by Summer 2013 which will then be presented at the ASME Energy Sustainability conference. The compilation so far includes essential definitions of terms like direct normal irradiance, incident angles, heat flows, and efficiencies on a system level. The definitions presented will be discussed together with existing standards like the ISO 80000 (physical quantities and units of measurement), the ISO 9488 (Solar energy-vocabulary) and other relevant sources. Although the list of terms is primarily put together for the work in the “guiSmo” project, it might serve as a basis for standardization in the official councils. An international group of solar experts is involved in the preparation of the document in order to ensure high quality and international support for the results.

Technical and economical evaluation of solar thermal power plants constantly gains more importance for industry and research. The reliability of the results highly depends on the assumptions made for the applied parameters. Reducing a power plant system to one single, deterministic number for evaluation, like the levelized cost of electricity (LCOE), might end in misleading results. Probabilistic approaches can help to better evaluate systems [1] and scenarios [2]. While industry looks for safety in investment and profitability, research is predominantly interested in the evaluation of concepts and the identification of promising new approaches. Especially for research, dealing with higher and hardly quantifiable uncertainties, it is desirable to get a detailed view of the system and its main influences. However, to get there, also a good knowledge on the stochastic interrelations and its interpretation is required. Therefore, this paper mainly assesses the influences of basic stochastic assumptions and suggests a methodology to consider suitable stochastic input, especially for parameters of systems still under research. As examples, the comparison between a parabolic trough plant with synthetic oil and direct steam generation is used.

Northern white ash had been the wood of choice for Major League Baseball (MLB) bats until the introduction of hard maple in the late 1990 s. Since the introduction of maple to the game, there has been a perceived increase in the rate of bats to exhibit multi-piece failures (MPF)–both ash and maple. Lab and field data indicate that while a maple bat is as equally likely to crack as an ash bat, maple is three times more likely than ash to exhibit an MPF. In 2009 MLB implemented a number of additional regulations and inspection processes for the wood billets in an effort to reduce the MPF rate. In 2010, another regulation was added requiring that before any new wood species can be introduced to the game, it must it must obtain approval from MLB Baseball Operations. This paper will describe a proposed wood species certification protocol to quantify its durability relative to ash, where ash is being taken as the acceptable baseline for durability. A demonstration of the protocol is conducted using yellow birch with white ash as the baseline. Finite element models of bats made of these two wood species are used to explore the relationship between wood density and bat durability.