tailieunhanh - design of wood aircraft structures phần 6

với $ 10 khoảng một tháng trước đây - một bản gốc trong hình dạng tuyệt vời, không kém. Trong khi tôi đang chờ đợi cho một bản gốc ANC-18 thả ra của bầu trời trên tôi, có nó trong PDF sẽ rất hữu ích. | L L L L J L L L L in z M 75272 r Figure -61. Relation between ultimate bearing strength and bearing strength at proportional limit for various types of members. must be distributed to each bolt in proportion to its resistance and the geometry of the bolt group. This often requires a trial and error calculation. . Bolt spacings. The following bolt spacing criteria are based on spruce. For other species the parallel-to-grain spacings and end margins should be multiplied by the expression Fs u 2 124 where Fcp allowable stress at proportional limit in compression parallel to the grain Fsv allowable shearing stress parallel to the grain of the material Spacings perpendicular to grain and edge margins as given below are applicable to all species. . Spacing of bolts loaded parallel to the grain. 1 1 Spacing parallel to the grain. The minimum distance from the center of any bolt to the edge of the next bolt in a spruce member having cross-banded reinforcing plates subjected to either tension or compression is given in figure 2-64. The. minimum distance from the edge of a bolt to the end of such a member subject to tension is also given. For spruce members without reinforcement these values must be increased by 50 percent. 118 0 r r REDUCTION FACTOR r Oĩỉ- DIRECTION Of GRAIN DIRECTION OF load LEGEND Pc ALLOWABLE LOAD OR STRESS PARALLEL TO GRAIN. Q ALLOWABLE LOAD or sTRESS PERPENDICULAR TO GRAIN. N ALLOWABLE LOAD OR STRESS AT INCLINATION e WITH THE DIRECTION OF GRAIN. 0 IO 9 ALLOWABLE LOAD in pounds or stress in psi FOR PỆữ lN-TENS HUNDREDS THOUSANDS ETC. EXAMPLE GWEN p AN ALLOWABLE BOLT LOAD PARALLEL ro GRAIN POUNDS Q AN ALLOWABLE LOAD PERPENDICULAR TO GRAIN 2 000 POUNDS. REQUIRED N AN ALLOWABLE LOAD AT AN ANGLE OF 40 TO GRAIN. SOLUTION CONNECT WITH A STRAIGHT LINE 6 000 POUNDS ON OX a WITH THE INTERSECTION ON OY b OF A VERTICAL LINE THROUGH 2 000 POUNDS. THE POINT WHERE THIS LINE ob INTERSECTS THE LINE REPRESENTING THE GWEN ANGLE 40 IS DIRECTLY ABOVE .