The human neck is especially vulnerable to severe injuries why it is of interest to gain a better understanding of the injury mechanisms involved. A 3D Finite Element (FE) model including the geometry of the individual neck muscles has been developed at Kungliga Tekniska Högskolan (KTH) and gives the possibility to study the strains inside the muscles. However, in this model the muscles are only hindered to interpenetrate and can glide relative each other with a roughly estimated coefficient of friction. The focus of this thesis has been to modify the FE-model in order to model the connectivity on a physiological basis using methods available in the used FE-software. The main reason for this was to get a more realistic muscle displacement without separations that are present in the current model. The connective tissue surrounding and connecting the muscles was modeled with two principal approaches. The first was based on a combination of FE-contacts where the material properties were contacts. The other approach was based on a new element type called Smoothed Particle Hydrodynamics (SPH) elements in combination with FE-contacts. Both approaches showed that the structural stiffness did not increase significantly, but the strain levels where somewhat elevated. Stability issues arouse with deleted elements and negative element volumes causing the FE‐contact based approach to fail prematurely. The SPH‐based approach had fewest deleted elements and completed the simulation but increased the calculation time with approximately 50 %. It was concluded that the implementation of a connection between the muscles had a relatively low influence on the strains and kinematics of the neck and could be used to avoid muscle separations. The influence on stability of the model was however more evident and the most stable result increased the calculation time significantly. / Den mänskliga nacken är en väldigt sårbar del av kroppen och det är därför av stort intresse att lära sig mer om de olika skademekanismerna inblandade. På Kungliga Tekniska Högskolan (KTH) har en 3D Finita Element (FE) modell utvecklats som inkluderar musklernas geometri och ger möjlighet att studera töjningarna inuti musklerna. Men i denna modell hindras musklerna endast från penetration och kan glida relativt varandra med en grovt uppskattad friktionskoefficient. I detta examensarbete har fokus legat på att modifiera FEM‐modellen för att modellera sammanbindningen mellan musklerna på en fysiologisk basis med hjälp av tillgängliga metoder i den använda FEM‐mjukvaran. Huvudmålet med detta var att uppnå mer realistiska muskelrörelser utan separationer som uppstår i den befintliga modellen. Den bindvävnad som omger och binder samman musklerna modellerades med två grundstrategier. Den första var baserad på en kombination av FEM‐kontakter där materialegenskaperna kopplades till styvheten i FEM-kontakterna. Den andra strategin baserades på en ny elementtyp kallad Smoothed Particle Hydrodynamics (SPH) i kombination med FEM‐kontakter. Båda strategierna visade att den strukturella styvheten inte ökade med några signifikanta nivåer, men töjningsnivåerna ökade något mer. En del stabilitets problem uppstod som gav raderade element och negativa elementvolymer vilket ledde till att den FEM‐kontakt baserade strategin kraschade innan simuleringen slutförts. Den SPH‐baserade strategin resulterade i minst antal raderade element och slutförde simuleringen men ökade beräkningstiden med c.a. 50 %. Det fastställdes att implementeringen av de nya metoderna hade en relativt liten påverkan på töjningar och kinematiken hos nacken och kan användas för att undvika muskelseparationer. Inverkan på stabiliteten hos modellen var dock mer märkbart och det stabilaste resultatet ökade beräkningstiden betydligt.

The design of a paperboard testing machine, developed in order to analyse the mechanical behaviour of paperboard during the combined of out-of-plane shear and compressive loading as in the deepdrawing process, is presented. The methodology to design a paperboard testing machine is discussed and the most appropriate concepts are compared and evaluated. The design process is presented in detail, and some pilot tests are performed to give an overview about the functionality of the manufactured prototype.

Both theoretically as well as in many applications like exhaust systems, ventilation pipes, mufflers, air intakes and also large scale industrial smoke stacks, it is of interest to understand how sound waves are scattered at duct exists. Especially for aeronautical application such as jet engines, the effect of coupling of acoustics and flow on sound radiation and reflection from a duct termination in a uniform is an important problem. In order to predict the acoustic performance in duct systems, it is essential to know how the incoming acoustic waves are propagated and transmitted and reflected. This thesis work aims at developing suitable simulation methods as extension to existing software and to validate these methods to experimental measurements and theory. Firstly, numerical simulations of fully developed flow through a duct exit has been carried out. The goal in this part is to obtain the mean values for the velocity and pressure. The commercial code Fluent 12.1 is used for numerical simulations in two space dimensions. Secondly, numerical simulations of the acoustic part has been studied with the commercial software Comsol 3.5a with the objective to investigate the ability of the frequency domain Navier-Stokes equations to the characteristic properties of the acoustics at the duct termination. Finally, numerical results are compared to available experimental results with acceptable agreement which shows successes and also constraints of the simulations.

The ACM 2 spot weld model is the currently most widely used spot weld model in industry. It is designed to be tuned using parameters to represent the stiffness characteristics of a spot weld in a suitable way. The choice of these parameters is however often associated with uncertainties. Therefore, the set of parameters with best performance is determined by employing an updating algorithm. Further, the result is compared to a new category of models, the so called Spider models, which intend to overcome mesh dependence in the spot weld area by re-meshing the structures locally. The results are formulated as guidelines for the optimum implementation of these spot weld models for structural dynamics. The studies are performed using two cut-out parts from a Volvo FH truck cabin. In addition, a new analytical approach for updating material data of isotropic shell structures is derived and the equations are verified using the same test pieces.

No description available.

To be able to verify that a cylinder head design meats the expectations a good test method is needed. The aim of this thesis is to determine the best way of testing with respect to validity, cost, time consumption, quantity of tested material and repeatability. The base of the new method is the current single head method and this have been expanded to the suit the cylinder head of a seven litre engine currently in production. In order to determine how many cylinders to test and the order of these simulations of fatigue have been performed. Comparing these different ways of testing was done with a comparison of the safety factor against fatigue in a reference case composed of the ignition sequence and 17 feasible test methods. From the simulation results two suitable test fixtures have been designed in Catia. A method composed of two phases of pulsation with cylinders 1, 3 and 5 in the first phase and 2, 4 and 6 in the second phase is suggested as test method.

No description available.

UMV är ett företag som konstruerar och tillverkar bestrykningsmaskiner till papper och kartongindustrin. På dessa pappersmaskiner finns det en schaber monterad, som har till uppgift att skrapa av en vals från smuts och bestrykningsmaterial. I dagsläget köps denna schaber in som ett färdigt system, medan många av de resterande delarna till bestrykningsmaskinen konstrueras av UMV och tillverkas av underleverantörer. UMV vill undersöka vad kostnaderna skulle bli om de själva skulle konstruera och tillverka en schaber vilket är orsaken till att detta examensarbete har skapats. Projektets huvudsakliga målsättning har varit att ta fram ett koncept på en schaber som är billigare än nuvarande inköpta schaber. Konstruktionen har utvecklats mot den kravspecifikation som har tagits fram i arbetet. Projektet inleddes med att en projektplan och en tidsplan skapades. Sedan undersöktes hur en bestrykningsmaskin fungerar. Vidare undersöktes även valet av lagring för schabern samt materialval. Efter detta steg framställdes olika koncept med hjälp av olika idégenereringsverktyg och ett koncept valdes sedan med hjälp av konceptvalsmatriser. Efter detta steg konstruerades hela schabern i ett CAD-program och ritningar framställdes för alla komponenter. Ritningar skickades sedan till UMV’s lokala leverantör CS produktion för att få offerter och en välgrundad kostnadskalkyl för konceptet. Målet med projektet har uppfyllts och schabern som har konstruerats uppfyller kravspecifikationen samt understiger kostnadskravet.

The knowledge of the dynamic behaviour of a milling process is very important for finding an optimum process window. In today's manufacturing industry the machining parameters are often predicted using experimental data from non-rotating spindles. Many times the predicted machining parameters prove to be ineffective and inaccurate which lead to reduced quality of the machined surface, tool wear, noise or at worst spindle failure. The best way to study the dynamics of the milling spindle is of course to measure the spindle response under actual operating conditions. Laser vibrometry is a non-contact, non-disturbing method commonly used for measurements of vibrations on static objects. The technique offers the possibility to measure vibrations on thin-walled (light), and rotating objects as well as sound fields. However, two major problems occur when measuring on rotating spindles: (1) speckle noise and (2) crosstalk between the vibration components. These two drawbacks make vibration measurements on rotating spindles difficult to interpret. In this Licentiate thesis the principles of laser vibrometry is introduced and the speckle noise and the crosstalk between the velocity components of a rotating spindle is studied experimentally. The rotating spindle is excited by an adaptive magnetic bearing and the response is measured by laser vibrometry and non-contact inductive displacement sensors simultaneously. The work shows that by polishing the measurement surface optically smooth we are able to avoid the speckle noise and the crosstalk problem. By using this approach, the vibrations as well as the roundness of the measured target can be resolved. Hence, the laser vibrometry technique can be used for measuring the spindle dynamics under operating conditions. Measurements on a bowed violin are performed. The chain of interacting parts of the played violin is studied: the string, the bridge and the plates as well as the generated sound field. The string is excited using a rotating bow apparatus and the vibrations from the string transmits to the violin body via the bridge and produces the sound. The measurements on the string shows stick-slip behaviour and the bridge measurements show that the string vibrations transmit to the bridge both in the horizontal and the vertical direction. Measurements on the plates show complex deflection shapes which are a combination of different eigenmodes. The sound fields emitted from the violin were measured and visualized for different harmonic partials of the played tone. However, the visualized sound field obtained by the laser vibrometer is a projection of the sound field along the laser light and the image obtained is a 2D map of the real 3D sound field. This effect is illustrated by measurements of a sound field emitted from three ultrasound transducers.

The growing effort to reduce vehicle weight and improve passive safety in the automotive industry has drastically increased the demand for ultra high strength steel components. There exist several production methods for such components, where the press hardening technique (hot stamping) is one of the most successful in producing complex components from boron steel. In order to accurately perform numerical Finite Element (FE) simulations of the actual thermo-mechanical forming, it is crucial to use correct material data and models. This work is focusing on two main aspects of the material characterisation as follows. The first is the flow stress of the austenite at elevated temperatures and different strain rates, relevant for the process, which is crucial for correctly predicting the strains in the component and the forming force. During a press hardening cycle, the actual forming is performed at high temperatures and the steel is in the austenitic state. The second, the austenite decomposition into daughter products such as ferrite, pearlite, bainite or martensite is a function of the thermal and mechanical history. To find the mechanical response (flow stress) for the austenite, a method based on multiple overlapping continuous cooling and compression tests (MOCCCT) in combination with inverse modelling has been developed. A validation test (in combination with the compression tests) shows good agreement with the simulated forming force, indicating that the estimated flow stress as a function of temperature, strain and strain rate is accurate in the actual application. The austenite decomposition model is developed and integrated as a material subroutine into the FE-code LS-DYNA. The model is based on the combined nucleation and growth rate equations proposed by Kirkaldy. A separate test to simulate different cooling histories along a boron alloyed steel sheet has been conducted. / Godkänd; 2004; 20070128 (ysko)